Bio

Current Role at Stanford


Manager, Cyclotron & Radiochemistry Facility

Honors & Awards


  • Travel grant for 20th International Symposium on Radiopharmaceutical Sciences, Society of Radiopharmaceutical Sciences (2013)
  • Travel grant for World Molecular Imaging Congress, World Molecular Imaging Society (2011)
  • Travel grant for 19th International Symposium on Radiopharmaceutical Sciences, Society of Radiopharmaceutical Sciences (2011)

Education & Certifications


  • PhD, Universitaet Tuebingen, Radiochemistry/Organic Chemistry (2008)
  • M.S. Engineering, Nanjing University of Technology, Bioengineer (2004)

Publications

All Publications


  • PET imaging of tumor glycolysis downstream of hexokinase through noninvasive measurement of pyruvate kinase M2. Science translational medicine Witney, T. H., James, M. L., Shen, B., Chang, E., Pohling, C., Arksey, N., Hoehne, A., Shuhendler, A., Park, J., Bodapati, D., Weber, J., Gowrishankar, G., Rao, J., Chin, F. T., Gambhir, S. S. 2015; 7 (310): 310ra169-?

    View details for DOI 10.1126/scitranslmed.aac6117

    View details for PubMedID 26491079

  • Preclinical Kinetic Analysis of the Caspase-3/7 PET Tracer 18F-C-SNAT: Quantifying the Changes in Blood Flow and Tumor Retention After Chemotherapy. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Palner, M., Shen, B., Jeon, J., Lin, J., Chin, F. T., Rao, J. 2015; 56 (9): 1415-1421

    Abstract

    Early detection of tumor response to therapy is crucial to the timely identification of the most efficacious treatments. We recently developed a novel apoptosis imaging tracer, (18)F-C-SNAT (C-SNAT is caspase-sensitive nanoaggregation tracer), that undergoes an intramolecular cyclization reaction after cleavage by caspase-3/7, a biomarker of apoptosis. This caspase-3/7-dependent reaction leads to an enhanced accumulation and retention of (18)F activity in apoptotic tumors. This study aimed to fully examine in vivo pharmacokinetics of the tracer through PET imaging and kinetic modeling in a preclinical mouse model of tumor response to systemic anticancer chemotherapy.Tumor-bearing nude mice were treated 3 times with intravenous injections of doxorubicin before undergoing a 120-min dynamic (18)F-C-SNAT PET/CT scan. Time-activity curves were extracted from the tumor and selected organs. A 2-tissue-compartment model was fitted to the time-activity curves from tumor and muscle, using the left ventricle of the heart as input function, and the pharmacokinetic rate constants were calculated.Both tumor uptake (percentage injected dose per gram) and the tumor-to-muscle activity ratio were significantly higher in the treated mice than untreated mice. Pharmacokinetic rate constants calculated by the 2-tissue-compartment model showed a significant increase in delivery and accumulation of the tracer after the systemic chemotherapeutic treatment. Delivery of (18)F-C-SNAT to the tumor tissue, quantified as K1, increased from 0.31 g?(mL?min)(-1) in untreated mice to 1.03 g?(mL?min)(-1) in treated mice, a measurement closely related to changes in blood flow. Accumulation of (18)F-C-SNAT, quantified as k3, increased from 0.03 to 0.12 min(-1), proving a higher retention of (18)F-C-SNAT in treated tumors independent from changes in blood flow. An increase in delivery was also found in the muscular tissue of treated mice without increasing accumulation.(18)F-C-SNAT has significantly increased tumor uptake and significantly increased tumor-to-muscle ratio in a preclinical mouse model of tumor therapy. Furthermore, our kinetic modeling of (18)F-C-SNAT shows that chemotherapeutic treatment increased accumulation (k3) in the treated tumors, independent of increased delivery (K1).

    View details for DOI 10.2967/jnumed.115.155259

    View details for PubMedID 26045308

  • Positron emission tomography imaging of drug-induced tumor apoptosis with a caspase-triggered nanoaggregation probe. Angewandte Chemie (International ed. in English) Shen, B., Jeon, J., Palner, M., Ye, D., Shuhendler, A., Chin, F. T., Rao, J. 2013; 52 (40): 10511-10514

    Abstract

    Drug Design: An (18) F-labeled caspase-3-sensitive nanoaggregation positron emission tomography tracer was prepared and evaluated for imaging the caspase-3 activity in doxorubicin-treated tumor xenografts. Enhanced retention of the (18) F activity in apoptotic tumors is achieved through intramolecular macrocyclization and in situ aggregation upon caspase-3 activation.

    View details for DOI 10.1002/anie.201303422

    View details for PubMedID 23881906

  • New Positron Emission Tomography (PET) Radioligand for Imaging sigma-1 Receptors in Living Subjects JOURNAL OF MEDICINAL CHEMISTRY James, M. L., Shen, B., Zavaleta, C. L., Nielsen, C. H., Mesangeau, C., Vuppala, P. K., Chan, C., Avery, B. A., Fishback, J. A., Matsumoto, R. R., Gambhir, S. S., McCurdy, C. R., Chin, F. T. 2012; 55 (19): 8272-8282

    Abstract

    ?-1 receptor (S1R) radioligands have the potential to detect and monitor various neurological diseases. Herein we report the synthesis, radiofluorination, and evaluation of a new S1R ligand 6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ([(18)F]FTC-146, [(18)F]13). [(18)F]13 was synthesized by nucleophilic fluorination, affording a product with >99% radiochemical purity (RCP) and specific activity (SA) of 2.6 1.2 Ci/?mol (n = 13) at end of synthesis (EOS). Positron emission tomography (PET) and ex vivo autoradiography studies of [(18)F]13 in mice showed high uptake of the radioligand in S1R rich regions of the brain. Pretreatment with 1 mg/kg haloperidol (2), nonradioactive 13, or BD1047 (18) reduced the binding of [(18)F]13 in the brain at 60 min by 80%, 82%, and 81%, respectively, suggesting that [(18)F]13 accumulation in mouse brain represents specific binding to S1Rs. These results indicate that [(18)F]13 is a promising candidate radiotracer for further evaluation as a tool for studying S1Rs in living subjects.

    View details for DOI 10.1021/jm300371c

    View details for Web of Science ID 000309643500008

    View details for PubMedID 22853801

  • Efficient Method for Site-Specific F-18-Labeling of Biomolecules Using the Rapid Condensation Reaction between 2-Cyanobenzothiazole and Cysteine BIOCONJUGATE CHEMISTRY Jeon, J., Shen, B., Xiong, L., Miao, Z., Lee, K. H., Rao, J., Chin, F. T. 2012; 23 (9): 1902-1908

    Abstract

    An efficient method based on a rapid condensation reaction between 2-cyanobenzothiazole (CBT) and cysteine has been developed for (18)F-labeling of N-terminal cysteine-bearing peptides and proteins. An (18)F-labeled dimeric cRGD ([(18)F]CBTRGD(2)) has been synthesized with an excellent radiochemical yield (92% based on radio-HPLC conversion, 80% decay-corrected, and isolated yield) and radiochemical purity (>99%) under mild conditions using (18)F-CBT, and shown good in vivo tumor targeting efficiency for PET imaging. The labeling strategy was also applied to the site-specific (18)F-labeling of a protein, Renilla lucifierase (RLuc8) with a cysteine residue at its N-terminus. The protein labeling was achieved with 12% of decay-corrected radiochemical yield and more than 99% radiochemical purity. This strategy should provide a general approach for efficient and site-specific (18)F-labeling of various peptides and proteins for in vivo molecular imaging applications.

    View details for DOI 10.1021/bc300273m

    View details for Web of Science ID 000308833600021

    View details for PubMedID 22845703

    View details for PubMedCentralID PMC3447118

  • First Experience with Clinical-Grade [F-18]FPP(RGD)(2): An Automated Multi-step Radiosynthesis for Clinical PET Studies MOLECULAR IMAGING AND BIOLOGY Chin, F. T., Shen, B., Liu, S., Berganos, R. A., Chang, E., Mittra, E., Chen, X., Gambhir, S. S. 2012; 14 (1): 88-95

    Abstract

    A reliable and routine process to introduce a new ?F-labeled dimeric RGD-peptide tracer ([?F]FPP(RGD?) for noninvasive imaging of ?(v)?? expression in tumors needed to be developed so the tracer could be evaluated for the first time in man. Clinical-grade [?F]FPP(RGD)? was screened in mouse prior to our first pilot study in human.[?F]FPP(RGD)? was synthesized by coupling 4-nitrophenyl-2-[?F]fluoropropionate ([?F]NPE) with the dimeric RGD-peptide (PEG?-c(RGDyK)?). Imaging studies with [?F]FPP(RGD)? in normal mice and a healthy human volunteer were carried out using small animal and clinical PET scanners, respectively.Through optimization of each radiosynthetic step, [?F]FPP(RGD)? was obtained with RCYs of 16.9??2.7% (n?=?8, EOB) and specific radioactivity of 114??72 GBq/?mol (3.08??1.95 Ci/?mol; n?=?8, EOB) after 170 min of radiosynthesis. In our mouse studies, high radioactivity uptake was only observed in the kidneys and bladder with the clinical-grade tracer. Favorable [?F]FPP(RGD)? biodistribution in human studies, with low background signal in the head, neck, and thorax, showed the potential applications of this RGD-peptide tracer for detecting and monitoring tumor growth and metastasis.A reliable, routine, and automated radiosynthesis of clinical-grade [?F]FPP(RGD)? was established. PET imaging in a healthy human volunteer illustrates that [?F]FPP(RGD)? possesses desirable pharmacokinetic properties for clinical noninvasive imaging of ?(v)?? expression. Further imaging studies using [?F]FPP(RGD)? in patient volunteers are now under active investigation.

    View details for DOI 10.1007/s11307-011-0477-3

    View details for Web of Science ID 000301583900012

    View details for PubMedID 21400112

    View details for PubMedCentralID PMC3617483

  • [F-18]-SuPAR: A Radiofluorinated Probe for Noninvasive Imaging of DNA Damage-Dependent Poly(ADP-ribose) Polymerase Activity BIOCONJUGATE CHEMISTRY Shuhendler, A. J., Cui, L., Chen, Z., Shen, B., Chen, M., James, M. L., Witney, T. H., Bazalova-Carter, M., Gambhir, S. S., Chin, F. T., Graves, E. E., Rao, J. 2019; 30 (5): 1331?42

    Abstract

    Poly(ADP ribose) polymerase (PARP) enzymes generate poly(ADP ribose) post-translational modifications on target proteins for an array of functions centering on DNA and cell stress. PARP isoforms 1 and 2 are critically charged with the surveillance of DNA integrity and are the first line guardians of the genome against DNA breaks. Here we present a novel probe ([18F]-SuPAR) for noninvasive imaging of PARP-1/2 activity using positron emission tomography (PET). [18F]-SuPAR is a radiofluorinated nicotinamide adenine dinucleotide (NAD) analog that can be recognized by PARP-1/2 and incorporated into the long branched polymers of poly(ADP ribose) (PAR). The measurement of PARP-1/2 activity was supported by a reduction of radiotracer uptake in vivo following PARP-1/2 inhibition with talazoparib treatment, a potent PARP inhibitor recently approved by FDA for treatment of breast cancer, as well as ex vivo colocalization of radiotracer analog and poly(ADP ribose). With [18F]-SuPAR, we were able to map the dose- and time-dependent activation of PARP-1/2 following radiation therapy in breast and cervical cancer xenograft mouse models. Tumor response to therapy was determined by [18F]-SuPAR PET within 8 h of administration of a single dose of radiation equivalent to one round of stereotactic ablative radiotherapy.

    View details for DOI 10.1021/acs.bioconjchem.9b00089

    View details for Web of Science ID 000468368300008

    View details for PubMedID 30973715

  • Efficient synthesis of carbon-11 labelled acylsulfonamides using [11C]CO carbonylation chemistry. Chemical communications (Cambridge, England) van der Wildt, B., Shen, B., Chin, F. T. 2019

    Abstract

    Herein, a novel method for carbon-11 labeling of acyl sulfonamides by a one-step insertive [11C]CO carbonylative cross-coupling reaction between aryl halides and sulfonamides is presented. Various model compounds as well as drug molecules LY573636 (tasisulam) and ABT-199 were obtained in excellent yields. This method provides a valuable and widely applicable contribution to the continuously expanding radiochemical toolbox for PET research.

    View details for PubMedID 30793132

  • Identifying Hypoperfusion in Moyamoya Disease With Arterial Spin Labeling and an [15O]-Water Positron Emission Tomography/Magnetic Resonance Imaging Normative Database. Stroke Fan, A. P., Khalighi, M. M., Guo, J., Ishii, Y., Rosenberg, J., Wardak, M., Park, J. H., Shen, B., Holley, D., Gandhi, H., Haywood, T., Singh, P., Steinberg, G. K., Chin, F. T., Zaharchuk, G. 2019: STROKEAHA118023426

    Abstract

    Background and Purpose- Noninvasive imaging of brain perfusion has the potential to elucidate pathophysiological mechanisms underlying Moyamoya disease and enable clinical imaging of cerebral blood flow (CBF) to select revascularization therapies for patients. We used hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) technology to characterize the distribution of hypoperfusion in Moyamoya disease and its relationship to vessel stenosis severity, through comparisons with a normative perfusion database of healthy controls. Methods- To image CBF, we acquired [15O]-water PET as a reference and simultaneously acquired arterial spin labeling (ASL) MRI scans in 20 Moyamoya patients and 15 age-matched, healthy controls on a PET/MRI scanner. The ASL MRI scans included a standard single-delay ASL scan with postlabel delay of 2.0 s and a multidelay scan with 5 postlabel delays (0.7-3.0s) to estimate and account for arterial transit time in CBF quantification. The percent volume of hypoperfusion in patients (determined as the fifth percentile of CBF values in the healthy control database) was the outcome measure in a logistic regression model that included stenosis grade and location. Results- Logistic regression showed that anterior ( P<0.0001) and middle cerebral artery territory regions ( P=0.003) in Moyamoya patients were susceptible to hypoperfusion, whereas posterior regions were not. Cortical regions supplied by arteries with stenosis on MR angiography showed more hypoperfusion than normal arteries ( P=0.001), but the extent of hypoperfusion was not different between mild-moderate versus severe stenosis. Multidelay ASL did not perform differently from [15O]-water PET in detecting perfusion abnormalities, but standard ASL overestimated the extent of hypoperfusion in patients ( P=0.003). Conclusions- This simultaneous PET/MRI study supports the use of multidelay ASL MRI in clinical evaluation of Moyamoya disease in settings where nuclear medicine imaging is not available and application of a normative perfusion database to automatically identify abnormal CBF in patients.

    View details for PubMedID 30636572

  • Simultaneous phase-contrast MRI and PET for noninvasive quantification of cerebral blood flow and reactivity in healthy subjects and patients with cerebrovascular disease. Journal of magnetic resonance imaging : JMRI Ishii, Y., Thamm, T., Guo, J., Khalighi, M. M., Wardak, M., Holley, D., Gandhi, H., Park, J. H., Shen, B., Steinberg, G. K., Chin, F. T., Zaharchuk, G., Fan, A. P. 2019

    Abstract

    H215 O-positron emission tomography (PET) is considered the reference standard for absolute cerebral blood flow (CBF). However, this technique requires an arterial input function measured through continuous sampling of arterial blood, which is invasive and has limitations with tracer delay and dispersion.To demonstrate a new noninvasive method to quantify absolute CBF with a PET/MRI hybrid scanner. This blood-free approach, called PC-PET, takes the spatial CBF distribution from a static H215 O-PET scan, and scales it to the whole-brain average CBF value measured by simultaneous phase-contrast MRI.Observational.Twelve healthy controls (HC) and 13 patients with Moyamoya disease (MM) as a model of chronic ischemic disease.3T/2D cardiac-gated phase-contrast MRI and H215 O-PET.PC-PET CBF values from whole brain (WB), gray matter (GM), and white matter (WM) in HCs were compared with literature values since 2000. CBF and cerebrovascular reactivity (CVR), which is defined as the percent CBF change between baseline and post-acetazolamide (vasodilator) scans, were measured by PC-PET in MM patients and HCs within cortical regions corresponding to major vascular territories. Statistical Tests: Linear, mixed effects models were created to compare CBF and CVR, respectively, between patients and controls, and between different degrees of stenosis.The mean CBF values in WB, GM, and WM in HC were 42 7 ml/100 g/min, 50 7 ml/100 g/min, and 23 3 ml/100 g/min, respectively, which agree well with literature values. Compared with normal regions (57 23%), patients showed significantly decreased CVR in areas with mild/moderate stenosis (47 17%, P = 0.011) and in severe/occluded areas (40 16%, P = 0.016). Data Conclusion: PC-PET identifies differences in cerebrovascular reactivity between healthy controls and cerebrovascular patients. PC-PET is suitable for CBF measurement when arterial blood sampling is not accessible, and warrants comparison to fully quantitative H215 O-PET in future studies.3 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019.

    View details for PubMedID 31044459

  • The characterization of 18F-hGTS13 for molecular imaging of xC- transporter activity with positron emission tomography. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Beinat, C., Gowrishankar, G., Shen, B., Alam, I. S., Robinson, E., Haywood, T., Patel, C. B., Azevedo, E. C., Castillo, J., Ilovich, O., Koglin, N., Schmitt-Willich, H., Berndt, M., Mueller, A., Zerna, M., Srinivasan, A., Gambhir, S. S. 2019

    Abstract

    Purpose: The aim of this study was development of an improved positron emission tomography (PET) radiotracer for measuring xC- activity with increased tumor uptake and reduced uptake in inflammatory cells compared to (S)-4-(3-18F-Fluoropropyl)-L-glutamic acid (18F-FSPG). Experimental design: A racemic glutamate derivative, 18F-hGTS13 was evaluated in cell culture and animal tumor models. 18F-hGTS13 was separated into C5-epimers and the corresponding 18F-hGTS13-isomer1 and 18F-hGTS13-isomer2 evaluated in H460 tumor bearing rats. Preliminary studies investigate the cellular uptake of 18F-hGTS13-isomer2 in multiple immune cell populations and states. Results:18F-hGTS13 demonstrated excellent H460 tumor visualization with high tumor-to-background ratios, confirmed by ex vivo biodistribution studies. Tumor associated radioactivity of 18F-hGTS13 (7.50.9%ID/g, n = 3) was significantly higher than with 18F-FSPG (4.60.7%ID/g, n = 3, P = 0.01). 18F-hGTS13-isomer2 exhibited excellent H460 tumor visualization (6.31.1%ID/g, n-3), and significantly reduced uptake in multiple immune cell populations relative to 18F-FSPG. 18F-hGTS13-isomer2 exhibited increased liver uptake relative to 18F-FSPG (4.60.8%ID/g vs. 0.70.01%ID/g) limiting its application in hepatocellular carcinoma. Conclusion:18F-hGTS13-isomer2 is a new PET radiotracer for molecular imaging of xC- activity which may provide information regarding tumor oxidation states. 18F-hGTS13-isomer2 has potential for clinical translation for imaging cancers of the thorax due to the low background signal in healthy tissue.

    View details for DOI 10.2967/jnumed.119.225870

    View details for PubMedID 31171595

  • Striatal dopamine deficits predict reductions in striatal functional connectivity in major depression: a concurrent 11C-raclopride positron emission tomography and functional magnetic resonance imaging investigation. Translational psychiatry Hamilton, J. P., Sacchet, M. D., Hjornevik, T., Chin, F. T., Shen, B., Kampe, R., Park, J. H., Knutson, B. D., Williams, L. M., Borg, N., Zaharchuk, G., Camacho, M. C., Mackey, S., Heilig, M., Drevets, W. C., Glover, G. H., Gambhir, S. S., Gotlib, I. H. 2018; 8 (1): 264

    Abstract

    Major depressive disorder (MDD) is characterized by the altered integration of reward histories and reduced responding of the striatum. We have posited that this reduced striatal activation in MDD is due to tonically decreased stimulation of striatal dopamine synapses which results in decremented propagation of information along the cortico-striatal-pallido-thalamic (CSPT) spiral. In the present investigation, we tested predictions of this formulation by conducting concurrent functional magnetic resonance imaging (fMRI) and 11C-raclopride positron emission tomography (PET) in depressed and control (CTL) participants. We scanned 16 depressed and 14 CTL participants with simultaneous fMRI and 11C-raclopride PET. We estimated raclopride binding potential (BPND), voxel-wise, and compared MDD and CTL samples with respect to BPND in the striatum. Using striatal regions that showed significant between-group BPND differences as seeds, we conducted whole-brain functional connectivity analysis using the fMRI data and identified brain regions in each group in which connectivity with striatal seed regions scaled linearly with BPND from these regions. We observed increased BPND in the ventral striatum, bilaterally, and in the right dorsal striatum in the depressed participants. Further, we found that as BPND increased in both the left ventral striatum and right dorsal striatum in MDD, connectivity with the cortical targets of these regions (default-mode network and salience network, respectively) decreased. Deficits in stimulation of striatal dopamine receptors in MDD could account in part for the failure of transfer of information up the CSPT circuit in the pathophysiology of this disorder.

    View details for PubMedID 30504860

  • A [11 C] CO dispensing system for rapid screening of carbonylation reactions. Journal of labelled compounds & radiopharmaceuticals van der Wildt, B., Shen, B., Chin, F. T. 2018

    Abstract

    [11 C] CO is a highly versatile synthon that allows for labeling at carbonyl positions of many molecules by means of transition metal-mediated carbonylation reactions. The intrinsic complexity of carbonylation reactions often requires tedious screening of reaction conditions for obtaining satisfying yields. Herein, a [11 C] CO dispending system for performing multiple reactions with a single batch of cyclotron-produced [11 C]CO2 is described. This semi-automated setup allows for more rapid and efficient screening of reactions and reaction conditions compared to the traditional 'one beam for one reaction' strategy.

    View details for PubMedID 30286517

  • Single-Cell Imaging Using Radioluminescence Microscopy Reveals Unexpected Binding Target for [18F]HFB MOLECULAR IMAGING AND BIOLOGY Kiru, L., Kim, T., Shen, B., Chin, F. T., Pratx, G. 2018; 20 (3): 378?87

    Abstract

    Cell-based therapies are showing great promise for a variety of diseases, but remain hindered by the limited information available regarding the biological fate, migration routes and differentiation patterns of infused cells in trials. Previous studies have demonstrated the feasibility of using positron emission tomography (PET) to track single cells utilising an approach known as positron emission particle tracking (PEPT). The radiolabel hexadecyl-4-[18F]fluorobenzoate ([18F]HFB) was identified as a promising candidate for PEPT, due to its efficient and long-lasting labelling capabilities. The purpose of this work was to characterise the labelling efficiency of [18F]HFB in vitro at the single-cell level prior to in vivo studies.The binding efficiency of [18F]HFB to MDA-MB-231 and Jurkat cells was verified in vitro using bulk gamma counting. The measurements were subsequently repeated in single cells using a new method known as radioluminescence microscopy (RLM) and binding of the radiolabel to the single cells was correlated with various fluorescent dyes.Similar to previous reports, bulk cell labelling was significantly higher with [18F]HFB (18.752.47dpm/cell, n = 6) than 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) (7.590.73dpm/cell, n = 7; p ? 0.01). However, single-cell imaging using RLM revealed that [18F]HFB accumulation in live cells (8.351.48cpm/cell, n=9) was not significantly higher than background levels (4.830.52cpm/cell, n=12; p > 0.05) and was 1.7-fold lower than [18F]FDG uptake in the same cell line (14.091.90cpm/cell, n=13; p<0.01). Instead, [18F]HFB was found to bind significantly to fragmented membranes associated with dead cell nuclei, suggesting an alternative binding target for [18F]HFB.This study demonstrates that bulk analysis alone does not always accurately portray the labelling efficiency, therefore highlighting the need for more routine screening of radiolabels using RLM to identify heterogeneity at the single-cell level.

    View details for PubMedID 29143174

    View details for PubMedCentralID PMC5940563

  • Successful treatment of chronic knee pain following localization by a sigma-1 receptor radioligand and PET/MRI: a case report JOURNAL OF PAIN RESEARCH Cipriano, P., Lee, S., Yoon, D., Shen, B., Tawfik, V., Curtin, C., Dragoo, J. L., James, M., Mccurdy, C., Chin, F., Biswal, S. 2018; 11: 2353?56

    Abstract

    The ability to accurately diagnose and objectively localize pain generators in chronic pain sufferers remains a major clinical challenge since assessment relies on subjective patient complaints and relatively non-specific diagnostic tools. Developments in clinical molecular imaging, including advances in imaging technology and radiotracer design, have afforded the opportunity to identify tissues involved in pain generation based on their pro-nociceptive condition. The sigma-1 receptor (S1R) is a pro-nociceptive receptor upregulated in painful, inflamed tissues, and it can be imaged using the highly specific radioligand 18F-FTC-146 with PET.A 50-year-old woman with a 7-year history of refractory, left-knee pain of unknown origin was referred to our pain management team. Over the past several years, she had undergone multiple treatments, including a lateral retinacular release, radiofrequency ablation of a peripheral nerve, and physical therapy. While certain treatments provided partial relief, her pain would inevitably return to its original state. Using simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) with the novel radiotracer 18F-FTC-146, imaging showed increased focal uptake of 18F-FTC-146 in the intercondylar notch, corresponding to an irregular but equivocal lesion identified in the simultaneously acquired MRI. These imaging results prompted surgical removal of the lesion, which upon resection was identified as an inflamed, intraarticular synovial lipoma. Removal of the lesion relieved the patient's pain, and to date the pain has not recurred.We present a case of chronic, debilitating knee pain that resolved with surgery following identification of the pathology with a novel clinical molecular imaging approach that detects chronic pain generators at the molecular and cellular level. This approach has the potential to identify and localize pain-associated pathology in a variety of chronic pain syndromes.

    View details for PubMedID 30349360

  • Production of diverse PET probes with limited resources: 24 F-18-labeled compounds prepared with a single radiosynthesizer PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Collins, J., Waldmann, C. M., Drake, C., Slavik, R., Ha, N. S., Sergeev, M., Lazari, M., Shen, B., Chin, F. T., Moore, M., Sadeghi, S., Phelps, M. E., Murphy, J. M., van Dam, R. 2017; 114 (43): 11309?14

    Abstract

    New radiolabeled probes for positron-emission tomography (PET) are providing an ever-increasing ability to answer diverse research and clinical questions and to facilitate the discovery, development, and clinical use of drugs in patient care. Despite the high equipment and facility costs to produce PET probes, many radiopharmacies and radiochemistry laboratories use a dedicated radiosynthesizer to produce each probe, even if the equipment is idle much of the time, to avoid the challenges of reconfiguring the system fluidics to switch from one probe to another. To meet growing demand, more cost-efficient approaches are being developed, such as radiosynthesizers based on disposable "cassettes," that do not require reconfiguration to switch among probes. However, most cassette-based systems make sacrifices in synthesis complexity or tolerated reaction conditions, and some do not support custom programming, thereby limiting their generality. In contrast, the design of the ELIXYS FLEX/CHEM cassette-based synthesizer supports higher temperatures and pressures than other systems while also facilitating flexible synthesis development. In this paper, the syntheses of 24 known PET probes are adapted to this system to explore the possibility of using a single radiosynthesizer and hot cell for production of a diverse array of compounds with wide-ranging synthesis requirements, alongside synthesis development efforts. Most probes were produced with yields and synthesis times comparable to literature reports, and because hardware modification was unnecessary, it was convenient to frequently switch among probes based on demand. Although our facility supplies probes for preclinical imaging, the same workflow would be applicable in a clinical setting.

    View details for PubMedID 29073049

  • F-FTC-146 in humans. Journal of nuclear medicine Hjrnevik, T., Cipriano, P. W., Shen, B., Hyung Park, J., Gulaka, P., Holley, D., Gandhi, H., Yoon, D., Mittra, E. S., Zaharchuk, G., Gambhir, S. S., McCurdy, C. R., Chin, F. T., Biswal, S. 2017

    Abstract

    The purpose of this study is to assess safety, biodistribution and radiation dosimetry in humans for the highly selective sigma-1 receptor (S1R) positron emission tomography (PET) agent (18)F-6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ((18)F-FTC-146). Methods: Ten healthy volunteers (HV; five female, five male; age: 34.3 6.5 years) were recruited, and written informed consent was obtained from all participants. Series of whole-body PET/magnetic resonance imaging (PET/MRI) examinations were acquired for up to three hours after injection (357.2 48.8 MBq). Blood samples were collected and standard vital signs (heart rate, pulse oximetry, and body temperature) were monitored at regular intervals. Regions-of-interest were delineated, time-activity curves were calculated, and organ uptake and dosimetry was estimated using PMOD 3.7 and Organ Linear Internal Dose Assessment (OLINDA). Results: All subjects tolerated the PET/MRI examination well, and no adverse reactions to (18)F-FTC-146 were reported. High accumulation of (18)F-FTC-146 was observed in S1R dense organs such as the pancreas and spleen, moderate uptake in the brain and myocardium, and low uptake in bone and muscle. High uptake was also observed in the kidneys and bladder, indicating renal tracer clearance. The effective dose (ED) of (18)F-FTC-146 was 0.0259 0.0034 mSv/MBq (range: 0.0215-0.0301 mSv/MBq). Conclusion: First-in-human studies with clinical-grade (18)F-FTC-146 were successful. Injection of (18)F-FTC-146 is safe, and absorbed doses are acceptable. The potential of (18)F-FTC-146 as an imaging agent for a variety of neuroinflammatory diseases is currently under investigation.

    View details for DOI 10.2967/jnumed.117.192641

    View details for PubMedID 28572487

  • F]FTC-146. Molecular imaging and biology Shen, B., Park, J. H., Hjrnevik, T., Cipriano, P. W., Yoon, D., Gulaka, P. K., Holly, D., Behera, D., Avery, B. A., Gambhir, S. S., McCurdy, C. R., Biswal, S., Chin, F. T. 2017

    Abstract

    Sigma-1 receptors (S1Rs) play an important role in many neurological disorders. Simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) with S1R radioligands may provide valuable information for diagnosing and guiding treatment for these diseases. Our previously reported S1R radioligand, [(18)F]FTC-146, demonstrated high affinity for the S1R (K i=0.0025nM) and excellent selectivity for the S1R over the sigma-2 receptor (S2Rs; K i=364nM) across several species (from mouse to non-human primate). Herein, we report the clinical-grade radiochemistry filed with exploratory Investigational New Drug (eIND) and first-in-human PET/MRI evaluation of [(18)F]FTC-146.[(18)F]FTC-146 is prepared via a direct [(18)F] fluoride nucleophilic radiolabeling reaction and formulated in 0.9% NaCl containing no more than 10% ethanol through sterile filtration. Quality control (QC) was performed based on USP 823 before doses were released for clinical use. The safety and whole body biodistribution of [(18)F]FTC-146 were evaluated using a simultaneous PET/MR scanner in two representative healthy human subjects.[(18)F]FTC-146 was synthesized with a radiochemical yield of 3.30.7% and specific radioactivity of 8.33.3Ci/?mol (n=10, decay corrected to EOB). Both radiochemical and chemical purities were >95%; the prepared doses were stable for 4h at ambient temperature. All QC test results met specified clinical criteria. The in vivo PET/MRI investigations showed that [(18)F]FTC-146 rapidly crossed the blood brain barrier and accumulated in S1R-rich regions of the brain. There were also radioactivity distributed in the peripheral organs, i.e., the lungs, spleen, pancreas, and thyroid. Furthermore, insignificant uptake of [(18)F]FTC-146 was observed in cortical bone and muscle.A reliable and automated radiosynthesis for providing routine clinical-grade [(18)F]FTC-146 for human studies was established in a modified GE TRACERlab FXFN. PET/MRI demonstrated the initial tracer biodistribution in humans, and clinical studies investigating different S1R-related diseases are in progress.

    View details for DOI 10.1007/s11307-017-1064-z

    View details for PubMedID 28280965

  • Image-derived input function estimation on a TOF-enabled PET/MR for cerebral blood flow mapping. Journal of cerebral blood flow and metabolism Khalighi, M. M., Deller, T. W., Fan, A. P., Gulaka, P. K., Shen, B., Singh, P., Park, J., Chin, F. T., Zaharchuk, G. 2017: 271678X17691784-?

    Abstract

    (15)O-H2O PET imaging is an accurate method to measure cerebral blood flow (CBF) but it requires an arterial input function (AIF). Historically, image-derived AIF estimation suffers from low temporal resolution, spill-in, and spill-over problems. Here, we optimized tracer dose on a time-of-flight PET/MR according to the acquisition-specific noise-equivalent count rate curve. An optimized dose of 850?MBq of (15)O-H2O was determined, which allowed sufficient counts to reconstruct a short time-frame PET angiogram (PETA) during the arterial phase. This PETA enabled the measurement of the extent of spill-over, while an MR angiogram was used to measure the true arterial volume for AIF estimation. A segment of the high cervical arteries outside the brain was chosen, where the measured spill-in effects were minimal. CBF studies were performed twice with separate [15O]-H2O injections in 10 healthy subjects, yielding values of 88??16, 44??9, and 58??11?mL/min/100?g for gray matter, white matter, and whole brain, with intra-subject CBF differences of 5.0??4.0%, 4.1??3.3%, and 4.5??3.7%, respectively. A third CBF measurement after the administration of 1?g of acetazolamide showed 35??23%, 29??20%, and 33??22% increase in gray matter, white matter, and whole brain, respectively. Based on these findings, the proposed noninvasive AIF method provides robust CBF measurement with (15)O-H2O PET.

    View details for DOI 10.1177/0271678X17691784

    View details for PubMedID 28155582

  • Long-Delay Arterial Spin Labeling Provides More Accurate Cerebral Blood Flow Measurements in Moyamoya Patients: A Simultaneous Positron Emission Tomography/MRI Study. Stroke Fan, A. P., Guo, J., Khalighi, M. M., Gulaka, P. K., Shen, B., Park, J. H., Gandhi, H., Holley, D., Rutledge, O., Singh, P., Haywood, T., Steinberg, G. K., Chin, F. T., Zaharchuk, G. 2017; 48 (9): 2441?49

    Abstract

    Arterial spin labeling (ASL) MRI is a promising, noninvasive technique to image cerebral blood flow (CBF) but is difficult to use in cerebrovascular patients with abnormal, long arterial transit times through collateral pathways. To be clinically adopted, ASL must first be optimized and validated against a reference standard in these challenging patient cases.We compared standard-delay ASL (post-label delay=2.025 seconds), multidelay ASL (post-label delay=0.7-3.0 seconds), and long-label long-delay ASL acquisitions (post-label delay=4.0 seconds) against simultaneous [15O]-positron emission tomography (PET) CBF maps in 15 Moyamoya patients on a hybrid PET/MRI scanner. Dynamic susceptibility contrast was performed in each patient to identify areas of mild, moderate, and severe time-to-maximum (Tmax) delays. Relative CBF measurements by each ASL scan in 20 cortical regions were compared with the PET reference standard, and correlations were calculated for areas with moderate and severe Tmax delays.Standard-delay ASL underestimated relative CBF by 20% in areas of severe Tmax delays, particularly in anterior and middle territories commonly affected by Moyamoya disease (P<0.001). Arterial transit times correction by multidelay acquisitions led to improved consistency with PET, but still underestimated CBF in the presence of long transit delays (P=0.02). Long-label long-delay ASL scans showed the strongest correlation relative to PET, and there was no difference in mean relative CBF between the modalities, even in areas of severe delays.Post-label delay times of ?4 seconds are needed and may be combined with multidelay strategies for robust ASL assessment of CBF in Moyamoya disease.

    View details for PubMedID 28765286

  • Visualizing Nerve Injury in a Neuropathic Pain Model with [(18)F]FTC-146 PET/MRI. Theranostics Shen, B., Behera, D., James, M. L., Reyes, S. T., Andrews, L., Cipriano, P. W., Klukinov, M., Lutz, A. B., Mavlyutov, T., Rosenberg, J., Ruoho, A. E., McCurdy, C. R., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T. 2017; 7 (11): 2794?2805

    Abstract

    The ability to locate nerve injury and ensuing neuroinflammation would have tremendous clinical value for improving both the diagnosis and subsequent management of patients suffering from pain, weakness, and other neurologic phenomena associated with peripheral nerve injury. Although several non-invasive techniques exist for assessing the clinical manifestations and morphological aspects of nerve injury, they often fail to provide accurate diagnoses due to limited specificity and/or sensitivity. Herein, we describe a new imaging strategy for visualizing a molecular biomarker of nerve injury/neuroinflammation, i.e., the sigma-1 receptor (S1R), in a rat model of nerve injury and neuropathic pain. The two-fold higher increase of S1Rs was shown in the injured compared to the uninjured nerve by Western blotting analyses. With our novel S1R-selective radioligand, [(18)F]FTC-146 (6-(3-[(18)F]fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one), and positron emission tomography-magnetic resonance imaging (PET/MRI), we could accurately locate the site of nerve injury created in the rat model. We verified the accuracy of this technique by ex vivo autoradiography and immunostaining, which demonstrated a strong correlation between accumulation of [(18)F]FTC-146 and S1R staining. Finally, pain relief could also be achieved by blocking S1Rs in the neuroma with local administration of non-radioactive [(19)F]FTC-146. In summary, [(18)F]FTC-146 S1R PET/MR imaging has the potential to impact how we diagnose, manage and treat patients with nerve injury, and thus warrants further investigation.

    View details for PubMedID 28824716

  • receptor. EJNMMI research Palner, M., Beinat, C., Banister, S., Zanderigo, F., Park, J. H., Shen, B., Hjoernevik, T., Jung, J. H., Lee, B. C., Kim, S. E., Fung, L., Chin, F. T. 2016; 6 (1): 80-?

    Abstract

    The availability of GABAA receptor binding sites in the brain can be assessed by positron emission tomography (PET) using the radioligand, [(18)F]flumazenil. However, the brain uptake and binding of this PET radioligand are influenced by anesthetic drugs, which are typically needed in preclinical imaging studies and clinical imaging studies involving patient populations that do not tolerate relatively longer scan times. The objective of this study was to examine the effects of anesthesia on the binding of [(18)F]flumazenil to GABAA receptors in mice.Brain and whole blood radioactivity concentrations were measured ex vivo by scintillation counting or in vivo by PET in four groups of mice following administration of [(18)F]flumazenil: awake mice and mice anesthetized with isoflurane, dexmedetomidine, or ketamine/dexmedetomidine. Dynamic PET recordings were obtained for 60min in mice anesthetized by either isoflurane or ketamine/dexmedetomidine. Static PET recordings were obtained at 25 or 55min after [(18)F]flumazenil injection in awake or dexmedetomidine-treated mice acutely anesthetized with isoflurane. The apparent distribution volume (VT*) was calculated for the hippocampus and frontal cortex from either the full dynamic PET scans using an image-derived input function or from a series of ex vivo experiments using whole blood as the input function.PET images showed persistence of high [(18)F]flumazenil uptake (up to 20 % ID/g) in the brains of mice scanned under isoflurane or ketamine/dexmedetomidine anesthesia, whereas uptake was almost indiscernible in late samples or static scans from awake or dexmedetomidine-treated animals. The steady-state VT* was twofold higher in hippocampus of isoflurane-treated mice and dexmedetomidine-treated mice than in awake mice.Anesthesia has pronounced effects on the binding and blood-brain distribution of [(18)F]flumazenil. Consequently, considerable caution must be exercised in the interpretation of preclinical and clinical PET studies of GABAA receptors involving the use of anesthesia.

    View details for PubMedID 27826950

  • Effects of common anesthetic agents on [F-18] flumazenil binding to the GABA(A) receptor EJNMMI RESEARCH Palner, M., Beinat, C., Banister, S., Zanderigo, F., Park, J. H., Shen, B., Hjoernevik, T., Jung, J. H., Lee, B. C., Kim, S. E., Fung, L., Chin, F. T. 2016; 6

    Abstract

    The availability of GABAA receptor binding sites in the brain can be assessed by positron emission tomography (PET) using the radioligand, [(18)F]flumazenil. However, the brain uptake and binding of this PET radioligand are influenced by anesthetic drugs, which are typically needed in preclinical imaging studies and clinical imaging studies involving patient populations that do not tolerate relatively longer scan times. The objective of this study was to examine the effects of anesthesia on the binding of [(18)F]flumazenil to GABAA receptors in mice.Brain and whole blood radioactivity concentrations were measured ex vivo by scintillation counting or in vivo by PET in four groups of mice following administration of [(18)F]flumazenil: awake mice and mice anesthetized with isoflurane, dexmedetomidine, or ketamine/dexmedetomidine. Dynamic PET recordings were obtained for 60min in mice anesthetized by either isoflurane or ketamine/dexmedetomidine. Static PET recordings were obtained at 25 or 55min after [(18)F]flumazenil injection in awake or dexmedetomidine-treated mice acutely anesthetized with isoflurane. The apparent distribution volume (VT*) was calculated for the hippocampus and frontal cortex from either the full dynamic PET scans using an image-derived input function or from a series of ex vivo experiments using whole blood as the input function.PET images showed persistence of high [(18)F]flumazenil uptake (up to 20 % ID/g) in the brains of mice scanned under isoflurane or ketamine/dexmedetomidine anesthesia, whereas uptake was almost indiscernible in late samples or static scans from awake or dexmedetomidine-treated animals. The steady-state VT* was twofold higher in hippocampus of isoflurane-treated mice and dexmedetomidine-treated mice than in awake mice.Anesthesia has pronounced effects on the binding and blood-brain distribution of [(18)F]flumazenil. Consequently, considerable caution must be exercised in the interpretation of preclinical and clinical PET studies of GABAA receptors involving the use of anesthesia.

    View details for DOI 10.1186/s13550-016-0235-2

    View details for Web of Science ID 000387828200001

  • In vivo assessment of behavioral recovery and circulatory exchange in the peritoneal parabiosis model SCIENTIFIC REPORTS Castellano, J. M., Palner, M., Li, S., Freeman, G. M., Andy Nguyen, A., Shen, B., Stan, T., Mosher, K. I., Chin, F. T., de Lecea, L., Luo, J., Wyss-Coray, T. 2016; 6

    Abstract

    The sharing of circulation between two animals using a surgical procedure known as parabiosis has created a wealth of information towards our understanding of physiology, most recently in the neuroscience arena. The systemic milieu is a complex reservoir of tissues, immune cells, and circulating molecules that is surprisingly not well understood in terms of its communication across organ systems. While the model has been used to probe complex physiological questions for many years, critical parameters of recovery and exchange kinetics remain incompletely characterized, limiting the ability to design experiments and interpret results for complex questions. Here we provide evidence that mice joined by parabiosis gradually recover much physiology relevant to the study of brain function. Specifically, we describe the timecourse for a variety of recovery parameters, including those for general health and metabolism, motor coordination, activity, and sleep behavior. Finally, we describe the kinetics of chimerism for several lymphocyte populations as well as the uptake of small molecules into the brains of mice following parabiosis. Our characterization provides an important resource to those attempting to understand the complex interplay between the immune system and the brain as well as other organ systems.

    View details for DOI 10.1038/srep29015

    View details for Web of Science ID 000378851500002

    View details for PubMedID 27364522

    View details for PubMedCentralID PMC4929497

  • Striatal dopamine D2/3 receptor regulation by stress inoculation in squirrel monkeys. Neurobiology of stress Lee, A. G., Nechvatal, J. M., Shen, B., Buckmaster, C. L., Levy, M. J., Chin, F. T., Schatzberg, A. F., Lyons, D. M. 2016; 3: 68-73

    Abstract

    Intermittent mildly stressful situations provide opportunities to learn, practice, and improve coping in a process called stress inoculation. Stress inoculation also enhances cognitive control and response inhibition of impulsive motivated behavior. Cognitive control and motivation have been linked to striatal dopamine D2 and/or D3 receptors (DRD2/3) in rodents, monkeys, and humans. Here, we study squirrel monkeys randomized early in life to stress inoculation with or without maternal companionship and a no-stress control treatment condition. Striatal DRD2/3 availability in adulthood was measured invivo by [(11)C]raclopride binding using positron emission tomography (PET). DRD2/3 availability was greater in caudate and putamen compared to ventral striatum as reported in PET studies of humans and other non-human primates. DRD2/3 availability in ventral striatum was also consistently greater in stress inoculated squirrel monkeys compared to no-stress controls. Squirrel monkeys exposed to stress inoculation in the presence of their mother did not differ from squirrel monkeys exposed to stress inoculation without maternal companionship. Similar effects in different social contexts extend the generality of our findings and together suggest that stress inoculation increases striatal DRD2/3 availability as a correlate of cognitive control in squirrel monkeys.

    View details for PubMedID 27981179

  • Efficient automated syntheses of high specific activity 6-[(18) F]fluorodopamine using a diaryliodonium salt precursor. Journal of labelled compounds & radiopharmaceuticals Neumann, K. D., Qin, L., Vavere, A. L., Shen, B., Miao, Z., Chin, F. T., Shulkin, B. L., Snyder, S. E., DiMagno, S. G. 2016; 59 (1): 30-34

    Abstract

    6-[(18)F]Fluorodopamine (6-[(18) F]F-DA) is a positron emission tomography radiopharmaceutical used to image sympathetic cardiac innervation and neuroendocrine tumors. Imaging with 6-[(18)F]F-DA is constrained, in part, by the bioactivity and neurotoxicity of 6-[(19)F]fluorodopamine. Furthermore, routine access to this radiotracer is limited by the inherent difficulty of incorporation of [(18)F]fluoride into electron-rich aromatic substrates. We describe the simple and direct preparation of high specific activity (SA) 6-[(18)F]F-DA from no-carrier-added (n.c.a.) [(18)F]fluoride. Incorporation of n.c.a. [(18)F]fluoride into a diaryliodonium salt precursor was achieved in 50-75% radiochemical yields (decay corrected to end of bombardment). Synthesis of 6-[(18)F]F-DA on the IBA Synthera and GE TRACERlab FX-FN automated platforms gave 6-[(18)F]F-DA in >99% chemical and radiochemical purities after HPLC purification. The final non-corrected yields of 6-[(18)F]F-DA were 25 4% (n = 4, 65 min) and 31 6% (n = 3, 75 min) using the Synthera and TRACERlab modules, respectively. Efficient access to high SA 6-[(18)F]F-DA from a diaryliodonium salt precursor and n.c.a. [(18)F]fluoride is provided by a relatively subtle change in reaction conditions - replacement of a polar aprotic solvent (acetonitrile) with a relatively nonpolar solvent (toluene) during the critical radiofluorination reaction. Implementation of this process on common radiochemistry platforms should make 6-[(18)F]F-DA readily available to the wider imaging community.

    View details for DOI 10.1002/jlcr.3367

    View details for PubMedID 26695865

    View details for PubMedCentralID PMC4715522

  • Further validation to support clinical translation of [(18)F]FTC-146 for imaging sigma-1 receptors. EJNMMI research Shen, B., James, M. L., Andrews, L., Lau, C., Chen, S., Palner, M., Miao, Z., Arksey, N. C., Shuhendler, A. J., Scatliffe, S., Kaneshige, K., Parsons, S. M., McCurdy, C. R., Salehi, A., Gambhir, S. S., Chin, F. T. 2015; 5 (1): 49-?

    Abstract

    This study aims to further evaluate the specificity and selectivity of [(18)F]FTC-146 and obtain additional data to support its clinical translation.The binding of [(19)F]FTC-146 to vesicular acetylcholine transporter (VAChT) was evaluated using [(3)H]vesamicol and PC12(A123.7) cells in an in vitro binding assay. The uptake and kinetics of [(18)F]FTC-146 in S1R-knockout mice (S1R-KO) compared to wild-type (WT) littermates was assessed using dynamic positron emission tomography (PET) imaging. Ex vivo autoradiography and histology were conducted using a separate cohort of S1R-KO/WT mice, and radiation dosimetry was calculated from WT mouse data (extrapolated for human dosing). Toxicity studies in Sprague-Dawley rats were performed with a dose equivalent to 250 the anticipated clinical dose of [(19)F]FTC-146 mass.VAChT binding assay results verified that [(19)F]FTC-146 displays negligible affinity for VAChT (K i?=?450??80nM) compared to S1R. PET images demonstrated significantly higher tracer uptake in WT vs. S1R-KO brain (4.57??1.07 vs. 1.34??0.4%ID/g at 20-25min, n?=?4, p?

    View details for DOI 10.1186/s13550-015-0122-2

    View details for PubMedID 26384292

  • Biodistribution of the (18)F-FPPRGD2 PET radiopharmaceutical in cancer patients: an atlas of SUV measurements. European journal of nuclear medicine and molecular imaging Minamimoto, R., Jamali, M., Barkhodari, A., Mosci, C., Mittra, E., Shen, B., Chin, F., Gambhir, S. S., Iagaru, A. 2015; 42 (12): 1850-1858

    Abstract

    The aim of this study was to investigate the biodistribution of 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) ((18)F-FPPRGD2) in cancer patients and to compare its uptake in malignant lesions with (18)F-FDG uptake.A total of 35 patients (11 men, 24 women, mean age 52.1??10.8years) were enrolled prospectively and had (18)F-FPPRGD2 PET/CT prior to treatment. Maximum standardized uptake values (SUVmax) and mean SUV (SUVmean) were measured in 23 normal tissues in each patient, as well as in known or suspected cancer lesions. Differences between (18)F-FPPRGD2 uptake and (18)F-FDG uptake were also evaluated in 28 of the 35 patients.Areas of high (18)F-FPPRGD2 accumulation (SUVmax range 8.9-94.4, SUVmean range 7.1-64.4) included the bladder and kidneys. Moderate uptake (SUVmax range 2.1-6.3, SUVmean range 1.1-4.5) was found in the choroid plexus, salivary glands, thyroid, liver, spleen, pancreas, small bowel and skeleton. Compared with (18)F-FDG, (18)F-FPPRGD2 showed higher tumor-to-background ratio in brain lesions (13.4??8.5 vs. 1.1??0.5, P?

    View details for DOI 10.1007/s00259-015-3096-4

    View details for PubMedID 26062933

  • PET imaging of tumor glycolysis downstream of hexokinase through noninvasive measurement of pyruvate kinase M2. Science translational medicine Witney, T. H., James, M. L., Shen, B., Chang, E., Pohling, C., Arksey, N., Hoehne, A., Shuhendler, A., Park, J., Bodapati, D., Weber, J., Gowrishankar, G., Rao, J., Chin, F. T., Gambhir, S. S. 2015; 7 (310): 310ra169-?

    Abstract

    Cancer cells reprogram their metabolism to meet increased biosynthetic demands, commensurate with elevated rates of replication. Pyruvate kinase M2 (PKM2) catalyzes the final and rate-limiting step in tumor glycolysis, controlling the balance between energy production and the synthesis of metabolic precursors. We report here the synthesis and evaluation of a positron emission tomography (PET) radiotracer, [(11)C]DASA-23, that provides a direct noninvasive measure of PKM2 expression in preclinical models of glioblastoma multiforme (GBM). In vivo, orthotopic U87 and GBM39 patient-derived tumors were clearly delineated from the surrounding normal brain tissue by PET imaging, corresponding to exclusive tumor-associated PKM2 expression. In addition, systemic treatment of mice with the PKM2 activator TEPP-46 resulted in complete abrogation of the PET signal in intracranial GBM39 tumors. Together, these data provide the basis for the clinical evaluation of imaging agents that target this important gatekeeper of tumor glycolysis.

    View details for DOI 10.1126/scitranslmed.aac6117

    View details for PubMedID 26491079

  • A Systematic Comparison of 18F-C-SNAT to Established Radiotracer Imaging Agents for the Detection of Tumor Response to Treatment. Clinical cancer research Witney, T. H., Hoehne, A., Reeves, R. E., Ilovich, O., Namavari, M., Shen, B., Chin, F. T., Rao, J., Gambhir, S. S. 2015; 21 (17): 3896-3905

    Abstract

    An early readout of tumor response to therapy through measurement of drug or radiation-induced cell death may provide important prognostic indications and improved patient management. It has been shown that the uptake of (18)F-C-SNAT can be used to detect early response to therapy in tumors by positron emission tomography (PET) via a mechanism of caspase-3-triggered nanoaggregation.Here, we compared the preclinical utility of (18)F-C-SNAT for the detection of drug-induced cell death to clinically evaluated radiotracers, (18)F-FDG, (99m)Tc-Annexin V, and (18)F-ML-10 in tumor cells in culture, and in tumor-bearing mice in vivo.In drug-treated lymphoma cells, (18)F-FDG, (99m)Tc-Annexin V, and (18)F-C-SNAT cell-associated radioactivity correlated well to levels of cell death (R(2) > 0.8; P < 0.001), with no correlation measured for (18)F-ML-10 (R(2) = 0.05; P > 0.05). A similar pattern of response was observed in two human NSCLC cell lines following carboplatin treatment. EL-4 tumor uptake of (99m)Tc-Annexin V and (18)F-C-SNAT were increased 1.4- and 2.1-fold, respectively, in drug-treated versus nave control animals (P < 0.05), although (99m)Tc-Annexin V binding did not correlate to ex vivo TUNEL staining of tissue sections. A differential response was not observed with either (18)F-FDG or (18)F-ML-10.We have demonstrated here that (18)F-C-SNAT can sensitively detect drug-induced cell death in murine lymphoma and human NSCLC. Despite favorable image contrast obtained with (18)F-C-SNAT, the development of next-generation derivatives, using the same novel and promising uptake mechanism, but displaying improved biodistribution profiles, are warranted for maximum clinical utility. Clin Cancer Res; 21(17); 3896-905. 2015 AACR.

    View details for DOI 10.1158/1078-0432.CCR-14-3176

    View details for PubMedID 25972517

    View details for PubMedCentralID PMC4558304

  • Single-Cell Analysis of [18F]Fluorodeoxyglucose Uptake by Droplet Radiofluidics. Analytical chemistry Trkcan, S., Nguyen, J., Vilalta, M., Shen, B., Chin, F. T., Pratx, G., Abbyad, P. 2015; 87 (13): 6667-6673

    Abstract

    Radiolabels can be used to detect small biomolecules with high sensitivity and specificity without interfering with the biochemical activity of the labeled molecule. For instance, the radiolabeled glucose analogue, [18F]fluorodeoxyglucose (FDG), is routinely used in positron emission tomography (PET) scans for cancer diagnosis, staging, and monitoring. However, despite their widespread usage, conventional radionuclide techniques are unable to measure the variability and modulation of FDG uptake in single cells. We present here a novel microfluidic technique, dubbed droplet radiofluidics, that can measure radiotracer uptake for single cells encapsulated into an array of microdroplets. The advantages of this approach are multiple. First, droplets can be quickly and easily positioned in a predetermined pattern for optimal imaging throughput. Second, droplet encapsulation reduces cell efflux as a confounding factor, because any effluxed radionuclide is trapped in the droplet. Last, multiplexed measurements can be performed using fluorescent labels. In this new approach, intracellular radiotracers are imaged on a conventional fluorescence microscope by capturing individual flashes of visible light that are produced as individual positrons, emitted during radioactive decay, traverse a scintillator plate placed below the cells. This method is used to measure the cell-to-cell heterogeneity in the uptake of tracers such as FDG in cell lines and cultured primary cells. The capacity of the platform to perform multiplexed measurements was demonstrated by measuring differential FDG uptake in single cells subjected to different incubation conditions and expressing different types of glucose transporters. This method opens many new avenues of research in basic cell biology and human disease by capturing the full range of stochastic variations in highly heterogeneous cell populations in a repeatable and high-throughput manner.

    View details for DOI 10.1021/acs.analchem.5b00792

    View details for PubMedID 26035453

  • Ether analogues of DPA-714 with subnanomolar affinity for the translocator protein (TSPO) EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY Banister, S. D., Beinat, C., Wilkinson, S. M., Shen, B., Bartoli, C., Selleri, S., Da Pozzo, E., Martini, C., Chin, F. T., Kassiou, M. 2015; 93: 392-400

    Abstract

    Sixteen new phenyl alkyl ether derivatives (12, 14-28) of the 5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-ylacetamide (DPA) class were synthesized and evaluated in a competition binding assay against [(3)H]PK11195 using 18kDa translocator protein (TSPO) derived from rat kidney mitochondrial fractions. All analogues showed superior binding affinities for TSPO compared to DPA-713 (5) and DPA-714 (6). Picomolar affinities were observed for this class of TSPO ligands in this assay for the first time, with phenethyl ether 28 showing the greatest affinity (Ki=0.13nM). Additionally, all analogues increased pregnenolone biosynthesis (134-331% above baseline) in a rat C6 glioma cell steroidogenesis assay.

    View details for DOI 10.1016/j.ejmech.2015.02.004

    View details for Web of Science ID 000351646100040

    View details for PubMedID 25725375

  • PET Imaging of Translocator Protein (18 kDa) in a Mouse Model of Alzheimer's Disease Using N-(2,5-Dimethoxybenzyl)-2-18F-Fluoro-N-(2-Phenoxyphenyl)Acetamide. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Belichenko, N. P., Nguyen, T. V., Andrews, L. E., Ding, Z., Liu, H., Bodapati, D., Arksey, N., Shen, B., Cheng, Z., Wyss-Coray, T., Gambhir, S. S., Longo, F. M., Chin, F. T. 2015; 56 (2): 311-316

    Abstract

    Herein we aimed to evaluate the utility of N-(2,5-dimethoxybenzyl)-2-(18)F-fluoro-N-(2-phenoxyphenyl)acetamide ((18)F-PBR06) for detecting alterations in translocator protein (TSPO) (18 kDa), a biomarker of microglial activation, in a mouse model of Alzheimer's disease (AD).Wild-type (wt) and AD mice (i.e., APP(L/S)) underwent (18)F-PBR06 PET imaging at predetermined time points between the ages of 5-6 and 15-16 mo. MR images were fused with PET/CT data to quantify (18)F-PBR06 uptake in the hippocampus and cortex. Ex vivo autoradiography and TSPO/CD68 immunostaining were also performed using brain tissue from these mice.PET images showed significantly higher accumulation of (18)F-PBR06 in the cortex and hippocampus of 15- to 16-mo-old APP(L/S) mice than age-matched wts (cortex/muscle: 2.43 0.19 vs. 1.55 0.15, P < 0.005; hippocampus/muscle: 2.41 0.13 vs. 1.55 0.12, P < 0.005). And although no significant difference was found between wt and APP(L/S) mice aged 9-10 mo or less using PET (P = 0.64), we were able to visualize and quantify a significant difference in (18)F-PBR06 uptake in these mice using autoradiography (cortex/striatum: 1.13 0.04 vs. 0.96 0.01, P < 0.05; hippocampus/striatum: 1.266 0.003 vs. 1.096 0.017, P < 0.001). PET results for 15- to 16-mo-old mice correlated well with autoradiography and immunostaining (i.e., increased (18)F-PBR06 uptake in brain regions containing elevated CD68 and TSPO staining in APP(L/S) mice, compared with wts).(18)F-PBR06 shows great potential as a tool for visualizing TSPO/microglia in the progression and treatment of AD.

    View details for DOI 10.2967/jnumed.114.141648

    View details for PubMedID 25613536

  • The relationship between serial [(18)?F]PBR06 PET imaging of microglial activation and motor function following stroke in mice. Molecular imaging and biology Lartey, F. M., Ahn, G., Ali, R., Rosenblum, S., Miao, Z., Arksey, N., Shen, B., Colomer, M. V., Rafat, M., Liu, H., Alejandre-Alcazar, M. A., Chen, J. W., Palmer, T., Chin, F. T., Guzman, R., Loo, B. W., Graves, E. 2014; 16 (6): 821-829

    Abstract

    Using [(18)?F]PBR06 positron emission tomography (PET) to characterize the time course of stroke-associated neuroinflammation (SAN) in mice, to evaluate whether brain microglia influences motor function after stroke, and to demonstrate the use of [(18)?F]PBR06 PET as a therapeutic assessment tool.Stroke was induced by transient middle cerebral artery occlusion (MCAO) in Balb/c mice (control, stroke, and stroke with poststroke minocycline treatment). [18F]PBR06 PET/CT imaging, rotarod tests, and immunohistochemistry (IHC) were performed 3, 11, and 22days poststroke induction (PSI).The stroke group exhibited significantly increased microglial activation, and impaired motor function. Peak microglial activation was 11days PSI. There was a strong association between microglial activation, motor function, and microglial protein expression on IHC. Minocycline significantly reduced microglial activation and improved motor function by day 22 PSI.[18F]PBR06 PET imaging noninvasively characterizes the time course of SAN, and shows increased microglial activation is associated with decreased motor function.

    View details for DOI 10.1007/s11307-014-0745-0

    View details for PubMedID 24865401

  • A Radiofluorinated Divalent Cystine Knot Peptide for Tumor PET Imaging MOLECULAR PHARMACEUTICS Jiang, L., Kimura, R. H., Ma, X., Tu, Y., Miao, Z., Shen, B., Chin, F. T., Shi, H., Gambhir, S. S., Cheng, Z. 2014; 11 (11): 3885-3892

    Abstract

    A divalent knottin containing two separate integrin binding epitopes (RGD) in the adjacent loops, 3-4A, was recently developed and reported in our previous publication. In the current study, 3-4A was radiofluorinated with a 4-nitrophenyl 2-(18)F-fluoropropinate ((18)F-NFP) group and the resulting divalent positron emission tomography (PET) probe, (18)F-FP-3-4A, was evaluated as a novel imaging probe to detect integrin ?v?3 positive tumors in living animals. Knottin 3-4A was synthesized by solid phase peptide synthesis, folded, and site-specifically conjugated with (18/19)F-NFP to produce the fluorinated peptide (18/19)F-fluoropropinate-3-4A ((18/19)F-FP-3-4A). The stability of (18)F-FP-3-4A was tested in both phosphate buffered saline (PBS) buffer and mouse serum. Cell uptake assays of the radiolabeled peptides were performed using U87MG cells. In addition, small animal PET imaging and biodistribution studies of (18)F-FP-3-4A were performed in U87MG tumor-bearing mice. The receptor targeting specificity of the radiolabeled peptide was also verified by coinjecting the probe with a blocking peptide cyclo(RGDyK). Our study showed that (18)F-FP-3-4A exhibited excellent stability in PBS buffer (pH 7.4) and mouse serum. Small animal PET imaging and biodistribution data revealed that (18)F-FP-3-4A exhibited rapid and good tumor uptake (3.76 0.59% ID/g and 2.22 0.62% ID/g at 0.5 and 1 h, respectively). (18)F-FP-3-4A was rapidly cleared from the normal tissues, resulting in excellent tumor-to-normal tissue contrasts. For example, liver uptake was only 0.39 0.07% ID/g and the tumor to liver ratio was 5.69 at 1 h p.i. Furthermore, coinjection of cyclo(RGDyK) with (18)F-FP-3-4A significantly inhibited tumor uptake (0.41 0.12 vs 1.02 0.19% ID/g at 2.5 h) in U87MG xenograft models, demonstrating specific accumulation of the probe in the tumor. In summary, the divalent probe (18)F-FP-3-4A is characterized by rapid and high tumor uptake and excellent tumor-to-normal tissue ratios. (18)F-FP-3-4A is a highly promising knottin based PET probe for translating into clinical imaging of tumor angiogenesis.

    View details for DOI 10.1021/mp500018s

    View details for Web of Science ID 000344307700012

  • (18)F-FPPRGD2 PET/CT: pilot phase evaluation of breast cancer patients. Radiology Iagaru, A., Mosci, C., Shen, B., Chin, F. T., Mittra, E., Telli, M. L., Gambhir, S. S. 2014; 273 (2): 549-559

    Abstract

    Purpose To present data from the first prospective pilot phase trial of breast cancer participants imaged with fluorine 18 ((18)F)-2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2), a radiopharmaceutical agent used in positron emission tomographic (PET) imaging. Materials and Methods The local institutional review board approved the HIPAA-compliant protocol. Written informed consent was obtained from each patient. Eight women (age range, 44-67 years; mean age, 54.3 years 8.8 [standard deviation]) with newly diagnosed or recurrent breast cancer were recruited between November 2010 and February 2011. (18)F-FPPRGD2 PET/computed tomographic (CT) and (18)F-fluorodeoxyglucose (FDG) PET/CT examinations were performed within 3 weeks of each other. Dynamic (18)F-FPPRGD2 PET and two whole-body static (18)F-FPPRGD2 PET/CT scans were obtained. During this time, vital signs and electrocardiograms were recorded at regular intervals. Blood samples were obtained before the injection of (18)F-FPPRGD2 and at 24 hours and 1 week after injection to evaluate for toxicity. A nonparametric version of multivariate analysis of variance was used to assess the safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare the maximum standardized uptake values (SUVmax). Results (18)F-FPPRGD2 was well tolerated, without noticeable changes in vital signs, on electrocardiograms, or in laboratory values. A total of 30 lesions were evaluated at (18)F-FDG PET/CT and (18)F-FPPRGD2 PET/CT. The primary breast lesions had (18)F-FPPRGD2 uptake with SUVmax of 2.4-9.4 (mean, 5.6 2.8) 60 minutes after injection, compared with (18)F-FDG uptake with SUVmax of 2.8-18.6 (mean, 10.4 7.2). Metastatic lesions also showed (18)F-FPPRGD2 uptake, with SUVmax of 2.4-9.7 (mean, 5.0 2.3) at 60 minutes, compared with (18)F-FDG uptake with SUVmax of 2.2-14.6 (mean, 6.6 4.2). Conclusion Data from this pilot phase study suggest that (18)F-FPPRGD2 is a safe PET radiopharmaceutical agent. Evaluation of (18)F-FPPRGD2 in participants with breast cancer demonstrated significant uptake in the primary lesion and in the metastases. Larger cohorts are required to confirm these preliminary findings. RSNA, 2014.

    View details for DOI 10.1148/radiol.14140028

    View details for PubMedID 25033190

  • Comparison of Two Site-Specifically F-18-Labeled Affibodies for PET Imaging of EGFR Positive Tumors MOLECULAR PHARMACEUTICS Su, X., Cheng, K., Jeon, J., Shen, B., Venturin, G. T., Hu, X., Rao, J., Chin, F. T., Wu, H., Cheng, Z. 2014; 11 (11): 3947-3956

    View details for DOI 10.1021/mp5003043

    View details for Web of Science ID 000344307700019

  • Fully Automated Production of Diverse 18F-Labeled PET Tracers on the ELIXYS Multireactor Radiosynthesizer Without Hardware Modification. Journal of nuclear medicine technology Lazari, M., Collins, J., Shen, B., Farhoud, M., Yeh, D., Maraglia, B., Chin, F. T., Nathanson, D. A., Moore, M., van Dam, R. M. 2014; 42 (3): 203-210

    Abstract

    Fully automated radiosynthesizers are continuing to be developed to meet the growing need for the reliable production of PET tracers made under current good manufacturing practice guidelines. There is a current trend toward supporting kitlike disposable cassettes that come preconfigured for particular tracers, thus eliminating the need for cleaning protocols between syntheses and enabling quick transitions to synthesizing other tracers. Though ideal for production, these systems are often limited for the development of novel tracers because of pressure, temperature, and chemical compatibility considerations. This study demonstrated the versatile use of the ELIXYS fully automated radiosynthesizer to adapt and produce 8 different (18)F-labeled PET tracers of varying complexity.Three-reactor syntheses of 2-deoxy-2-(18)F-fluoro-?-d-arabinofuranosylcytosine (d-(18)F-FAC), 2-deoxy-2-(18)F-fluoro-5-methyl-?-l-arabinofuranosyluracil (l-(18)F-FMAU), and 2-deoxy-2-(18)F-fluoro-5-ethyl-?-d-arabinofuranosyluracil (d-(18)F-FEAU) along with the 1-reactor syntheses of d-(18)F-FEAU, (18)F-FDG, 3-deoxy-3-(18)F-fluoro-l-thymidine ((18)F-FLT), (18)F-fallypride, 9-(4-(18)F-fluoro-3-hydroxymethylbutyl)-guanine ((18)F-FHBG), and N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB), were all produced using ELIXYS without the need for any hardware modifications or reconfiguration. Synthesis protocols were adapted and slightly modified from those in the literature but were not fully optimized. Furthermore, (18)F-FLT, (18)F-FDG, and (18)F-fallypride were produced sequentially on the same day and used for preclinical imaging of A431 tumor-bearing severe combined immunodeficient mice and wild-type BALB/c mice. To assess future translation to the clinical setting, several batches of tracers were subjected to a full set of quality control tests.All tracers were produced with radiochemical yields comparable to those in the literature. (18)F-FLT, (18)F-FDG, and (18)F-fallypride were successfully used to image the mice, with results consistent with those reported in the literature. All tracers that were subjected to clinical quality control tests passed.The ELIXYS radiosynthesizer facilitates rapid tracer development and is capable of producing multiple (18)F-labeled PET tracers suitable for clinical applications using the same hardware setup.

    View details for DOI 10.2967/jnmt.114.140392

    View details for PubMedID 25033883

  • PET Imaging of Stroke-Induced Neuroinflammation in Mice Using [F-18]PBR06 MOLECULAR IMAGING AND BIOLOGY Lartey, F. M., Ahn, G., Shen, B., Cord, K., Smith, T., Chua, J. Y., Rosenblum, S., Liu, H., James, M. L., Chernikova, S., Lee, S. W., Pisani, L. J., Tirouvanziam, R., Chen, J. W., Palmer, T. D., Chin, F. T., Guzman, R., Graves, E. E., Loo, B. W. 2014; 16 (1): 109-117

    Abstract

    The purpose of this study is to evaluate the 18kDa translocator protein (TSPO) radioligand [(18)F]N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline ([(18)F]PBR06) as a positron emission tomography (PET) imaging biomarker of stroke-induced neuroinflammation in a rodent model.Stroke was induced by transient middle cerebral artery occlusion in Balb/c mice. Dynamic PET/CT imaging with displacement and preblocking using PK111195 was performed 3days later. PET data were correlated with immunohistochemistry (IHC) for the activated microglial markers TSPO and CD68 and with autoradiography.[(18)F]PBR06 accumulation peaked within the first 5min postinjection, then decreased gradually, remaining significantly higher in infarct compared to noninfarct regions. Displacement or preblocking with PK11195 eliminated the difference in [(18)F]PBR06 uptake between infarct and noninfarct regions. Autoradiography and IHC correlated well spatially with uptake on PET.[(18)F]PBR06 PET specifically images TSPO in microglial neuroinflammation in a mouse model of stroke and shows promise for imaging and monitoring microglial activation/neuroinflammation in other disease models.

    View details for DOI 10.1007/s11307-013-0664-5

    View details for PubMedID 23836504

  • Evaluation of s-1 receptor radioligand 18F-FTC-146 in rats and squirrel monkeys using PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Shen, B., Nielsen, C. H., Behera, D., Buckmaster, C. L., Mesangeau, C., Zavaleta, C., Vuppala, P. K., Jamalapuram, S., Avery, B. A., Lyons, D. M., McCurdy, C. R., Biswal, S., Gambhir, S. S., Chin, F. T. 2014; 55 (1): 147-153

    Abstract

    The noninvasive imaging of ?-1 receptors (S1Rs) could provide insight into their role in different diseases and lead to novel diagnostic/treatment strategies. The main objective of this study was to assess the S1R radiotracer (18)F-FTC-146 in rats. Preliminary squirrel monkey imaging and human serum/liver microsome studies were performed to gain information about the potential of (18)F-FTC-146 for eventual clinical translation.The distribution and stability of (18)F-FTC-146 in rats were assessed via PET/CT, autoradiography, ? counting, and high-performance liquid chromatography (HPLC). Preliminary PET/MRI of squirrel monkey brain was conducted along with HPLC assessment of (18)F-FTC-146 stability in monkey plasma and human serum.Biodistribution studies showed that (18)F-FTC-146 accumulated in S1R-rich rat organs, including the lungs, pancreas, spleen, and brain. Pretreatment with known S1R compounds, haloperidol, or BD1047, before radioligand administration, significantly attenuated (18)F-FTC-146 accumulation in all rat brain regions by approximately 85% (P < 0.001), suggesting radiotracer specificity for S1Rs. Similarly, PET/CT and autoradiography results demonstrated accumulation of (18)F-FTC-146 in rat brain regions known to contain S1Rs and that this uptake could be blocked by BD1047 pretreatment. Ex vivo analysis of (18)F-FTC-146 in the brain showed that only intact radiotracer was present at 15, 30, and 60 min, whereas rapid metabolism of residual (18)F-FTC-146 was observed in rat plasma. Preliminary monkey PET/MRI studies demonstrated specific accumulation of (18)F-FTC-146 in the brain (mainly in cortical structures, cerebellum, and vermis) that could be attenuated by pretreatment with haloperidol. HPLC of monkey plasma suggested radioligand metabolism, whereas (18)F-FTC-146 appeared to be stable in human serum. Finally, liver microsome studies revealed that (18)F-FTC-146 has a longer half-life in human microsomes, compared with rodents.Together, these results indicate that (18)F-FTC-146 is a promising tool for visualizing S1Rs in preclinical studies and that it has potential for mapping these sites in the human brain.

    View details for DOI 10.2967/jnumed.113.120261

    View details for PubMedID 24337599

  • A F-18-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Hoehne, A., Behera, D., Parsons, W. H., James, M. L., Shen, B., Borgohain, P., Bodapati, D., Prabhakar, A., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T., Du Bois, J. 2013; 135 (48): 18012-18015

    Abstract

    Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.

    View details for DOI 10.1021/ja408300e

    View details for Web of Science ID 000328100000002

    View details for PubMedID 24261833

  • Integrin-Targeted Molecular Imaging of Experimental Abdominal Aortic Aneurysms by 18F-labeled Arg-Gly-Asp Positron-Emission Tomography. Circulation. Cardiovascular imaging Kitagawa, T., Kosuge, H., Chang, E., James, M. L., Yamamoto, T., Shen, B., Chin, F. T., Gambhir, S. S., Dalman, R. L., McConnell, M. V. 2013; 6 (6): 950-956

    Abstract

    Background- Both inflammation and neoangiogenesis contribute to abdominal aortic aneurysm (AAA) disease. Arg-Gly-Asp-based molecular imaging has been shown to detect the integrin ?v?3. We studied a clinical dimeric (18)F-labeled Arg-Gly-Asp positron-emission tomography (PET) agent ((18)F-FPPRGD2) for molecular imaging of experimental AAAs. Methods and Results- Murine AAAs were induced in Apo-E-deficient mice by angiotensin II infusion, with monitoring of aortic diameter on ultrasound. AAA (n=10) and saline-infused control mice (n=7) were injected intravenously with (18)F-FPPRGD2, as well as an intravascular computed tomography contrast agent, then scanned using a small-animal PET/computed tomography scanner. Aortic uptake of (18)F-FPPRGD2 was quantified by percentage-injected dose per gram and target-to-=0.003; median target-to-=0.0008). Ex vivo autoradiography demonstrated high uptake of (18)F-FPPRGD2 into the AAA wall, with immunohistochemistry showing substantial cluster of differentiation (CD)-11b(+) macrophages and CD-31(+) neovessels. Target-to-=-0.29, P=0.41) but did strongly correlate with both mural macrophage density (r=0.79, P=0.007) and neovessel counts (r=0.87, P=0.001) on immunohistochemistry. Conclusions- PET imaging of experimental AAAs using (18)F-FPPRGD2 detects biologically active disease, correlating to the degree of vascular inflammation and neoangiogenesis. This may provide a clinically translatable molecular imaging approach to characterize AAA biology to predict risk beyond size alone.

    View details for DOI 10.1161/CIRCIMAGING.113.000234

    View details for PubMedID 23995363

  • Synthesis of ligand-functionalized water-soluble [F-18]YF3 nanoparticles for PET imaging NANOSCALE Xiong, L., Shen, B., Behera, D., Gambhir, S. S., Chin, F. T., Rao, J. 2013; 5 (8): 3253-3256

    Abstract

    We report a simple, efficient synthesis of novel (18)F-labeled imaging agents based on YF3 nanoparticles. Targeting ligands and antitumor drug molecules can be introduced onto the YF3 nanoparticles in a one-pot synthesis. The (18)F-labeling reaction proceeds in aqueous solutions at room temperature with excellent radiolabeling yields (>80%) in a very short time (5-10 min). (18)F-labeled YF3 nanoparticles displayed high stability in mouse and human serum, and their application for mapping lymph nodes in live rats after local injection has also been demonstrated.

    View details for DOI 10.1039/c3nr00335c

    View details for Web of Science ID 000316959500019

    View details for PubMedID 23508229

    View details for PubMedCentralID PMC3645980

  • Synthesis of O-[2-[F-18]fluoro-3-(2-nitro-1H-imidazole-1-yl)propyl]tyrosine ([F-18]FNT]) as a new class of tracer for imaging hypoxia JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY Malik, N., Lin, X., Loeffler, D., Shen, B., Solbach, C., Reischl, G., Voelter, W., Machulla, H. 2012; 292 (3): 1025-1033
  • Recent Progress in Radiofluorination of Peptides for PET Molecular Imaging CURRENT ORGANIC SYNTHESIS Liu, S., Shen, B., Chin, F. T., Cheng, Z. 2011; 8 (4): 584-592
  • Pilot Pharmacokinetic and Dosimetric Studies of F-18-FPPRGD2: A PET Radiopharmaceutical Agent for Imaging alpha(v)beta(3) Integrin Levels RADIOLOGY Mittra, E. S., Goris, M. L., Iagaru, A. H., Kardan, A., Burton, L., Berganos, R., Chang, E., Liu, S., Shen, B., Chin, F. T., Chen, X., Gambhir, S. S. 2011; 260 (1): 182-191

    Abstract

    To assess the safety, biodistribution, and dosimetric properties of the positron emission tomography (PET) radiopharmaceutical agent fluorine 18 ((18)F) FPPRGD2 (2-fluoropropionyl labeled PEGylated dimeric RGD peptide [PEG3-E{c(RGDyk)}2]), which is based on the dimeric arginine-glycine-aspartic acid (RGD) peptide sequence and targets ?(v)?(3) integrin, in the first volunteers imaged with this tracer.The protocol was approved by the institutional review board, and written informed consent was obtained from all participants. Five healthy volunteers underwent whole-body combined PET-computed tomography 0.5, 1.0, 2.0, and 3.0 hours after tracer injection (mean dose, 9.5 mCi 3.4 [standard deviation] [351.5 MBq 125.8]; mean specific radioactivity, 1200 mCi/mmol 714 [44.4 GBq/mmol 26.4]). During this time, standard vital signs, electrocardiographic (ECG) readings, and blood sample values (for chemistry, hematologic, and liver function tests) were checked at regular intervals and 1 and 7 days after the injection. These data were used to evaluate tracer biodistribution and dosimetric properties, time-activity curves, and the stability of laboratory values. Significant changes in vital signs and laboratory values were evaluated by using a combination of population-averaged generalized estimating equation regression and exact paired Wilcoxon tests.The administration of (18)F-FPPRGD2 was well tolerated, with no marked effects on vital signs, ECG readings, or laboratory values. The tracer showed the same pattern of biodistribution in all volunteers: primary clearance through the kidneys (0.360 rem/mCi 0.185 [0.098 mSv/MBq 0.050]) and bladder (0.862 rem/mCi 0.436 [0.233 mSv/MBq 0.118], voiding model) and uptake in the spleen (0.250 rem/mCi 0.168 [0.068 mSv/MBq 0.046]) and large intestine (0.529 rem/mCi 0.236 [0.143 mSv/MBq 0.064]). The mean effective dose of (18)F-FPPRGD2 was 0.1462 rem/mCi 0.0669 (0.0396 mSv/MBq 0.0181). With an injected dose of 10 mCi (370 MBq) and a 1-hour voiding interval, a patient would be exposed to an effective radiation dose of 1.5 rem (15 mSv). Above the diaphragm, there was minimal uptake in the brain ventricles, salivary glands, and thyroid gland. Time-activity curves showed rapid clearance from the vasculature, with a mean 26% 17 of the tracer remaining in the circulation at 30 minutes and most of the activity occurring in the plasma relative to cells (mean whole blood-plasma ratio, 0.799 0.096).(18)F-FPPRGD2 has desirable pharmacokinetic and biodistribution properties. The primary application is likely to be PET evaluation of oncologic patients-especially those with brain, breast, or lung cancer. Specific indications may include tumor staging, identifying patients who would benefit from antiangiogenesis therapy, and separating treatment responders from nonresponders early.

    View details for DOI 10.1148/radiol.11101139

    View details for Web of Science ID 000291932300021

    View details for PubMedID 21502381

    View details for PubMedCentralID PMC3121013

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