Bio

Honors & Awards


  • Cardiovascular Institute: T32 Imaging Fellow, Stanford University

Professional Education


  • Bachelor of Science, Loyola Marymount University (2009)
  • Master of Science, University of Southern California (2014)
  • Doctor of Philosophy, University of Southern California (2017)

Research & Scholarship

Lab Affiliations


Publications

All Publications


  • White Matter Has Impaired Resting Oxygen Delivery in Sickle Cell Patients. American journal of hematology Chai, Y., Bush, A. M., Coloigner, J., Nederveen, A. J., Tamrazi, B., Vu, C., Choi, S., Coates, T. D., Lepore, N., Wood, J. C. 2019

    Abstract

    Although modern medical management has lowered overt stroke occurrence in patients with sickle cell disease (SCD), progressive white matter (WM) damage remains common. It is known that cerebral blood flow (CBF) increases to compensate for anemia, but sufficiency of cerebral oxygen delivery, especially in the WM, has not been systematically investigated. Cerebral perfusion was measured by arterial spin labeling in 32 SCD patients (age range: 10-42 years old, 14 males, 7 with HbSC, 25 HbSS) and 25 age and race-matched healthy controls (age range: 15-45 years old, 10 males, 12 with HbAS, 13 HbAA); 8/24 SCD patients were receiving regular blood transfusions and 14/24 non-transfused SCD patients were taking hydroxyurea. Imaging data from control subjects was used to calculate maps for CBF and oxygen delivery in SCD patients and their T-score maps. Whole brain CBF was increased in SCD patients with a mean T-score of 0.5 and correlated with lactate dehydrogenase (r2 = 0.58, p<0.0001). When corrected for oxygen content and arterial saturation, whole brain and grey matter (GM) oxygen delivery were normal in SCD, but WM oxygen delivery was 35% lower than in controls. Age and hematocrit were the strongest predictors for WM CBF and oxygen delivery in patients with SCD. There was spatial co-localization between regions of low oxygen delivery and white matter hyperintensities on T2 FLAIR imaging. To conclude, oxygen delivery is preserved in the GM of SCD patients, but is decreased throughout the WM, particularly in areas prone to WM silent strokes. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30697803

  • Hemolysis and Tricuspid Regurgitation Jet Velocity Predict Mortality in Patients with Sickle Cell Disease Shah, P., Bush, A., Suriany, S., Liu, H., Forman, H. J., Chalacheva, P., Thuptimdang, W., Sunwoo, J., Veluswamy, S., Denton, C., Khaleel, M., Kato, R., Perumbeti, A., Sposto, R., Khoo, M., Coates, T. D., Wood, J. C., Detterich, J. A. AMER SOC HEMATOLOGY. 2018
  • Diminished cerebral oxygen extraction and metabolic rate in sickle cell disease using T2 relaxation under spin tagging MRI MAGNETIC RESONANCE IN MEDICINE Bush, A. M., Coates, T. D., Wood, J. C. 2018; 80 (1): 294?303

    Abstract

    T2 MRI oximetry can noninvasively determine oxygen saturation (Y) but requires empirical MR calibration models to convert the measured blood transverse relaxation (T2b ) into Y. The accuracy of existing T2b models in the presence of blood disorders such as sickle cell disease (SCD) remains unknown.A Carr Purcell Meiboom Gill T2 preparation sequence was used to make 83 whole blood measurements from 11 subjects with SCD to derive an ex vivo sickle hemoglobin (HbS) T2b model. Forearm venous blood gas, sagittal sinus T2 (T2 Relaxation Under Spin Tagging) and total brain blood flow (phase contrast MRI) were measured in 37 healthy controls and 33 SCD subjects (age 24.6??10.2 years). Cerebral oxygen saturation, extraction fraction, and metabolic rate estimates were calculated using three separate T2b models. Cerebral and forearm oxygen extraction fraction were compared.Ex vivo, SCD blood had greater saturation dependent relaxivity than control blood, with a weak dependence on HbS and no dependence on hematocrit. In vivo, the HbS T2b model predicted Yv values with lowest coefficient of variation (compared with existing T2b models) and the strongest correlation with peripheral venous oximetry (r2 ?=?.29). The HbS T2b model predicted systematically higher Yv measurements in SCD patients (73??5 and 61??6; P?

    View details for PubMedID 29194727

    View details for PubMedCentralID PMC5876140

  • Pseudo continuous arterial spin labeling quantification in anemic subjects with hyperemic cerebral blood flow MAGNETIC RESONANCE IMAGING Bush, A., Chai, Y., Choi, S., Vaclavu, L., Holland, S., Nederveen, A., Coates, T., Wood, J. 2018; 47: 137?46

    Abstract

    To investigate possible sources of quantification errors in global cerebral blood flow (CBF) measurements by comparing pseudo continuous arterial spin labeling (PCASL) and phase contrast (PC) MRI in anemic, hyperemic subjects.All studies were performed on a Philips 3T Achieva MRI scanner. PC and PCASL CBF examinations were performed in 10 healthy, young adult subjects and 18 young adults with chronic anemia syndromes including sickle cell disease and thalassemia. CBF estimates from single and two compartment ASL kinetic models were compared. Numerical simulation and flow phantom experiments were used to explore the effects of blood velocity and B1+ on CBF quantification and labeling efficiency.PCASL CBF underestimated PC in both populations using a single compartment model (30.19.2% control, 45.217.2% anemia). Agreement substantially improved using a two-compartment model (-8.06.0% control, 11.712.3% anemia). Four of the anemic subjects exhibited venous outflow of ASL signal, suggestive of cerebrovascular shunt, possibly confounding PC-PCASL comparisons. Additionally, sub-study experiments demonstrated that B1+ was diminished at the labeling plane (82.95.1%), resulting in suboptimal labeling efficiency. Correcting labeling efficiency for diminished B1+, PCASL slightly overestimated PC CBF in controls (-15.46.8%) and resulted in better matching of CBF estimates in anemic subjects (0.710.0% without outflow, 10.59.4% with outflow).This work demonstrates that a two-compartment model is critical for PCASL quantification in hyperemic subjects. Venous outflow and B1+ under-excitation may also contribute to flow underestimation, but further study of these effects is required.

    View details for PubMedID 29229306

    View details for PubMedCentralID PMC5834316

  • oximetry. Magnetic resonance in medicine Bush, A., Borzage, M., Detterich, J., Kato, R. M., Meiselman, H. J., Coates, T., Wood, J. C. 2017; 77 (6): 2364-2371

    Abstract

    We sought a human blood T2 -oximetery calibration curve over the wide range of hematocrits commonly found in anemic patients applicable with T2 relaxation under spin tagging (TRUST).Blood was drawn from five healthy control subjects. Ninety-three in vitro blood transverse relaxation (T2b ) measurements were performed at 37C over a broad range of hematocrits (10-55%) and oxygen saturations (14-100%) at 3 Tesla (T). In vivo TRUST was performed on 35 healthy African American control subjects and 11 patients with chronic anemia syndromes.1/T2 rose linearly with hematocrit (r(2) ?=?0.96), for fully saturated blood. Upon desaturation, 1/T2 rose linearly with the square of the oxygen extraction, (1-Y)(2) , and the slope was linearly proportional to hematocrit (r(2) ?=?0.88). The resulting bilinear model between 1/T2 , (1-Y)(2) , and hematocrit had a combined r(2) of 0.96 and a coefficient of variation of 6.1%. Using the in vivo data, the bilinear model had significantly lower bias and variability than existing calibrations, particularly for low hematocrits. In vivo Bland Altman analysis demonstrated clinically relevant bias that was -6% (absolute saturation) for hematocrits near 30% and rose to?+?6% for hematocrits near 45%.This work introduces a robust bilinear calibration model that should be used for MRI oximetry. Magn Reson Med 77:2364-2371, 2017. 2016 International Society for Magnetic Resonance in Medicine.

    View details for DOI 10.1002/mrm.26311

    View details for PubMedID 27385283

    View details for PubMedCentralID PMC5218988

  • Determinants of resting cerebral blood flow in sickle cell disease AMERICAN JOURNAL OF HEMATOLOGY Bush, A. M., Borzage, M. T., Choi, S., Vaclavu, L., Tamrazi, B., Nederveen, A. J., Coates, T. D., Wood, J. C. 2016; 91 (9): 912-917

    Abstract

    Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2) ?=?0.69, P?

    View details for DOI 10.1002/ajh.24441

    View details for Web of Science ID 000385237100159

    View details for PubMedID 27263497

    View details for PubMedCentralID PMC4987198

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