Clinical Focus

  • Radiology
  • abdominal imaging and uroradiology
  • Diagnostic Radiology

Academic Appointments

Professional Education

  • Board Certification: Diagnostic Radiology, American Board of Radiology (1977)
  • Residency:UCSF Medical Center (1977) CA
  • Internship:Providence Medical Center S (1974) WA
  • Medical Education:Mcgill University (1972) Canada

Research & Scholarship

Current Research and Scholarly Interests

Studies include development and preliminary clinical evaluation of advanced techniques for ultrasonic imaging and tissue characterization. A number of studies are ongoing involving advanced techniques of magnetic resonance imaging and spectroscopy with application to the GU tract. Specific projects at the present time include: 1) Creation of ultrasound images which encode frequency information in an attempt to more fully describe tissue than conventional ultrasound images. 2) Determination of renal blood flow with cine phase contrast MRI in both native and transplant kidneys. 3) Magnetic resonance imaging and spectroscopy of prostatic carcinoma. 4) Magnetic resonance imaging of venous thrombosis.


2016-17 Courses


All Publications

  • Cine Phase Contrast MRI Determination of Renal Bloodflow. Investigator Radiol. In Press Sommer FG, Noorbehesht, et al
  • Radiology research and rock soup RADIOLOGY Sommer, F. G. 2007; 242 (2): 637-637

    View details for DOI 10.1148/radiol.2422060219

    View details for Web of Science ID 000244032100041

    View details for PubMedID 17255436

  • Can single-kidney glomerular filtration rate be determined with contrast-enhanced CT? Radiology Sommer, F. G. 2007; 242 (2): 325-326


    Daghini et al used a pig model to estimate single-kidney GFR with dynamic contrast-enhanced CT scanning. Three techniques were evaluated, two of which (the modified Patlak method and the gamma variate model) yielded GFR estimates that correlated significantly with determinations made by using standard inulin clearance techniques. The findings hold promise that noninvasive in vivo assessment of single-kidney renal function may be achieved in patients.

    View details for PubMedID 17255402

  • Estimation of renal extraction fraction based on postcontrast venous and arterial differential T-1 values: An error analysis MAGNETIC RESONANCE IN MEDICINE Levin, Y. S., Chow, L. C., Pec, N. J., Sommer, F. G., Spielman, D. M. 2005; 54 (2): 309-316


    An error analysis for quantifying single kidney extraction fraction (EF) via differential T1 measurements in the renal vein (RV) and renal artery (RA) is presented. Sources of error include blood flow effects, the effect of a short repetition time (TR), and the impact of uncertainties in the T1 estimates on the final EF calculations. Blood flow effects were investigated via simulation. For a range of blood velocities in the renal vein that may be found in kidney disease, incomplete refreshment of blood between readouts results in significant errors in T1 estimation. For a .5-cm slice, 110-ms sampling interval, and T1 of 600 ms, T1 estimation to within 5% of true T1 requires an average through-plane velocity of 6.75 cm/s for parabolic flow, and 3.5 cm/s for plug flow. Improvement can be achieved by accurately estimating the fraction of blood that has not refreshed between readouts (f(old)), while the quality of the T1 estimate varies with the accuracy of f(old) estimation. Shortening of the TR was investigated using phantom and in vivo studies. T1 was estimated to within 3% of the true value on phantoms, and within 5% of the true value for flowing blood for TR = 2T1. The estimated EF is shown to be very sensitive to the difference between T(1RA) and T(1RV). To achieve 10% or 20% uncertainty in the EF estimate, T1 in the renal vein and renal artery must be estimated to within approximately 1% or 2%. Because of limitations on measurement accuracy and precision, this method appears to be impractical at this time.

    View details for Web of Science ID 000230765700008

    View details for PubMedID 16032662

  • Effects of spatial and temporal resolution for MR image-guided thermal ablation of prostate with transurethral ultrasound JOURNAL OF MAGNETIC RESONANCE IMAGING Pisani, L. J., Ross, A. B., Diederich, C. J., Nau, W. H., Sommer, F. G., Glover, G. H., Butts, K. 2005; 22 (1): 109-118


    To describe approaches for determining optimal spatial and temporal resolutions for the proton resonance frequency shift method of quantitative magnetic resonance temperature imaging (MRTI) guidance of transurethral ultrasonic prostate ablation.Temperature distributions of two transurethral ultrasound applicators (90 degrees sectored tubular and planar arrays) for canine prostate ablation were measured via MRTI during in vivo sonication, and agree well with two-dimensional finite difference model simulations at various spatial resolutions. Measured temperature distributions establish the relevant signal-to-noise ratio (SNR) range for thermometry in an interventional MR scanner, and are reconstructed at different resolutions to compare resultant temperature measurements. Various temporal resolutions are calculated by averaging MRTI frames.When noise is added to simulated temperature distributions for tubular and planar applicators, the minimum root mean squared (RMS) error is achieved by reconstructing to pixel sizes of 1.9 and 1.7 mm, respectively. In in vivo measurements, low spatial resolution MRTI data are shown to reduce the noise without significantly affecting thermal dose calculations. Temporal resolution of 0.66 frames/minute leads to measurement errors of more than 12 degrees C during rapid heating.Optimizing MRTI pixel size entails balancing large pixel SNR gain with accuracy in representing underlying temperature distributions.

    View details for DOI 10.1002/jmri.20339

    View details for Web of Science ID 000230128900015

    View details for PubMedID 15971190

  • Value of curved planar reformations in MDCT of abdominal pathology AMERICAN JOURNAL OF ROENTGENOLOGY Desser, T. S., Sommer, F. G., Jeffrey, R. B. 2004; 182 (6): 1477-1484

    View details for Web of Science ID 000221555900028

    View details for PubMedID 15149993

  • Single breath-hold diffusion-weighted imaging of the abdomen JOURNAL OF MAGNETIC RESONANCE IMAGING Chow, L. C., Bammer, R., Moseley, M. E., Sommer, F. G. 2003; 18 (3): 377-382


    To generate high quality diffusion-weighted images (DWI) and corresponding isotropic ADC maps of the abdomen with full organ (kidneys) coverage in a single breath-hold.DWI was performed in 12 healthy subjects with an asymmetric, spin-echo, single-shot EPI readout on a system with high performance gradients (40 mT/minute). The isotropic diffusion coefficient was measured from maps and SNR was determined for both diffusion-weighted and reference images in the liver, spleen, pancreas, and kidneys. In six patients, single-axis diffusion encoding along three orthogonal axes (12 NEX) was employed to assess anisotropic diffusion in kidneys.This technique yielded images of quality and resolution which compares favorably to that of prior work. SNR ranged from 27.0 in liver to 44.1 in kidneys for the diffusion-weighted images, and from 19.6 in liver to 39.0 in kidneys in reference images. ADCs obtained in the renal medulla, renal cortex, liver, spleen, and pancreas were (2091 +/- 55) x 10(-6), (2580 +/- 53) x 10(-6), (1697 +/- 52) x 10(-6), (1047 +/- 82) x 10(-6), and (2605 +/- 168) x 10(-6) mm(2)/second, respectively (mean +/- SE). Apparent diffusion coefficient (ADC) in the renal medulla and cortex were significantly different by paired t-test (P = 4.22 x 10(-10)). Renal medulla and cortex yielded anisotropy indices (AI) of 0.129 and 0.067, respectively.1) Single-shot SE EPI DWI in the abdomen with this technique provides high quality images and maps with full organ coverage in a single breath-hold; 2) ADCs obtained in the renal medulla and cortex are significantly different; and 3) diffusion within the renal medulla is moderately anisotropic.

    View details for DOI 10.1002/jmri.10353

    View details for Web of Science ID 000185016700017

    View details for PubMedID 12938137

  • Noninvasive measurement of extraction fraction and single-kidney glomerular filtration rate with MR imaging in swine with surgically created renal artery stenoses RADIOLOGY Coulam, C. H., Lee, J. H., Wedding, K. L., Spielman, D. M., Pelc, N. J., Kee, S. T., Hill, B. B., Bouley, D. M., Derby, G. C., Myers, B. D., Sawyer-Glover, A. M., Sommer, F. G. 2002; 223 (1): 76-82


    To test whether magnetic resonance (MR) imaging enables accurate measurement of extraction fraction (EF) in swine with unilateral renal ischemia and to evaluate effects of renal arterial stenosis on EF and single-kidney glomerular filtration rate.High-grade unilateral renal arterial stenoses were surgically created in eight pigs. Direct measurements of renal venous and arterial inulin concentration provided reference standard estimates of single-kidney EF. Pigs were imaged with a 1.5-T imager to estimate EF, renal blood flow, and glomerular filtration rate. A breath-hold inversion-recovery spiral sequence was used to measure T1 of blood in the infrarenal inferior vena cava and renal veins after intravenous administration of gadopentetate dimeglumine, and these data were used to calculate EF. Cine-phase contrast material-enhanced imaging of the renal arteries provided quantitative renal blood flow measurements. Bilateral single-kidney glomerular filtration rate was then determined: glomerular filtration rate = renal blood flow x (1 - hematocrit level) x EF.A statistically significant linear correlation was found between EF, as determined with MR imaging, and inulin (r = 0.77). As compared with kidneys without renal arterial stenosis, kidneys with renal arterial stenosis showed 50% (0.14/0.28) EF reduction (P <.01) and 59% glomerular filtration rate reduction (P <.01).MR imaging shows promise for in vivo measurement of EF and glomerular filtration rate, which may be useful in assessing the clinical importance of renal arterial stenosis.

    View details for DOI 10.1148/radiol.2231010420

    View details for Web of Science ID 000174611900011

    View details for PubMedID 11930050

  • Maintenance and recovery stages of postischemic acute renal failure in humans AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY Ramaswamy, D., Corrigan, G., Polhemus, C., Boothroyd, D., Scandling, J., Sommer, F. G., Alfrey, E., Higgins, J., Deen, W. M., Olshen, R., Myers, B. D. 2002; 282 (2): F271-F280


    Postischemic injury in 38 recipients of 7-day-old cadaveric renal allografts was classified into sustained (n = 15) or recovering (n = 23) acute renal failure (ARF) according to the prevailing inulin clearance. Recipients of long-standing allografts that functioned optimally (n = 16) and living transplant donors undergoing nephrectomy (n = 10) served as functional and structural controls, respectively. A combination of physiological and morphometric techniques were used to evaluate glomerular filtration rate and its determinants 1-3 h after reperfusion and again on day 7 to elucidate the mechanism for persistent hypofiltration in ARF that is sustained. Glomerular filtration rate in the sustained ARF group on day 7 was depressed by 90% (mean +/- SD); the corresponding fall in renal plasma flow was proportionately less. Neither plasma oncotic pressure nor the single-nephron ultrafiltration coefficient differed between the sustained ARF and the control group, however. A model of glomerular ultrafiltration and a sensitivity analysis were used to compute the prevailing transcapillary hydraulic pressure gradient (DeltaP), the only remaining determinant of DeltaP. This revealed that DeltaP varied between 27 and 28 mmHg in sustained ARF and 32-38 mmHg in recovering ARF on day 7 vs. 47-54 mmHg in controls. Sustained ARF was associated with persistent tubular dilatation. We conclude that depression of DeltaP, perhaps due partially to elevated tubule pressure, is the predominant cause of hypofiltration in the maintenance stage of ARF that is sustained for 7 days.

    View details for Web of Science ID 000173348100011

    View details for PubMedID 11788441

  • Measurement of renal volumes with contrast-enhanced MRI Coulam, C. H., Bouley, D. M., Sommer, F. G. JOHN WILEY & SONS INC. 2002: 174-179


    To determine the accuracy of in vivo magnetic resonance imaging (MRI) measurement of total renal parenchymal volume and medullary fraction. MATERIALS andSixteen kidneys in eight pigs were imaged with a multiphasic contrast-enhanced fast three-dimensional sequence on a 1.5-T imager. Kidney segmentation, followed by a process of signal intensity thresholding for cortical and nephrographic phase datasets, allowed for MRI measurements of parenchymal volume and medullary fraction. Autopsy provided reference standards of renal volume, weight, and medullary fraction.An excellent correlation was found between MRI measurement of total renal parenchymal volume and autopsy volume (R2 = 0.86) and weight (R2 = 0.90). Medullary fraction (mean +/- SD) measured with MRI was 0.120 +/- 0.067, and with autopsy was 0.116 +/- 0.025 (t-test P = 0.84, F-test P = 0.001).MRI measurements of total renal volume are accurate. MRI measurements of medullary fraction show promise, but precision is limited when using a simple signal intensity thresholding algorithm.

    View details for DOI 10.1002/jmri.10058

    View details for Web of Science ID 000174756200008

    View details for PubMedID 11836773

  • Power Doppler imaging and resistance index measurement in the evaluation of acute renal transplant rejection JOURNAL OF CLINICAL ULTRASOUND Chow, L., Sommer, F. G., Huang, J., Li, K. C. 2001; 29 (9): 483-490


    This study was designed to test the hypotheses that power Doppler imaging has a predictive value in the assessment of acute renal allograft rejection and that the information garnered from the combination of resistance index (RI) determination and power Doppler imaging has an even greater predictive value in this assessment.Power Doppler images obtained prior to 96 sequential renal allograft biopsies in 92 patients with suspected renal transplant rejection were retrospectively graded for parenchymal vascularity on a scale of 1 to 4: 1, normal, uniform cortical flow; 2, mild peripheral cortical hypoperfusion; 3, vascular pruning in cortex and medulla; and 4, no visible parenchymal flow, with flow seen only in central vessels. Power Doppler grades and RIs for these cases were compared to graft biopsy results.No statistically significant association was observed between parenchymal vascularity as graded by power Doppler imaging, RI, and the presence of acute transplant rejection.Neither grading of vascularity on power Doppler images, RI measurement, nor the combination of these methods is an accurate means of detecting renal allograft rejection.

    View details for Web of Science ID 000171994800001

    View details for PubMedID 11745858

  • Multidetector CT urography with abdominal compression and three-dimensional reconstruction AMERICAN JOURNAL OF ROENTGENOLOGY Chow, L. C., Sommer, F. G. 2001; 177 (4): 849-855

    View details for Web of Science ID 000171144700019

    View details for PubMedID 11566687

  • Contrast-enhanced three-dimensional fast spoiled gradient-echo renal MR imaging: Evaluation of vascular and nonvascular disease RADIOGRAPHICS Heiss, S. G., Shifrin, R. Y., Sommer, G. 2000; 20 (5): 1341-1352


    Breath-hold contrast material enhanced three-dimensional (3D) fast spoiled gradient-echo (FSPGR) sequences are valuable techniques for evaluation of renal arteries and veins and diagnosis of significant renal arterial stenosis at magnetic resonance (MR) imaging. The excellent spatial and contrast resolution with these techniques, combined with the ability to perform studies in multiple vascular phases, also make them attractive for the diagnosis of a wide range of nonvascular processes that affect the kidneys, including renal infections, renal parenchymal diseases, and renal trauma. Particularly when combined with T1- and T2-weighted MR imaging, the contrast-enhanced techniques are highly effective for characterization of renal masses owing to the ability to portray dynamic contrast enhancement. The ability to display venous structures with contrast-enhanced 3D FSPGR techniques helps staging of renal cell carcinoma. This article presents examples of the wide range of vascular and nonvascular renal diseases that may be effectively imaged with contrast material enhanced 3D FSPGR techniques and illustrates the usefulness of the techniques for renal MR imaging.

    View details for Web of Science ID 000171509700012

    View details for PubMedID 10992022

  • PAH extraction and estimation of plasma flow in human postischemic acute renal failure AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY Corrigan, G., Ramaswamy, D., Kwon, O., Sommer, F. G., Alfrey, E. J., Dafoe, D. C., Olshen, R. A., Scandling, J. D., Myers, B. D. 1999; 277 (2): F312-F318


    We determined the effect of postischemic injury to the human renal allograft on p-aminohippurate (PAH) extraction (E(PAH)) and renal blood flow. We evaluated renal function in 44 allograft recipients on two occasions: 1-3 h after reperfusion (day 0) and again on postoperative day 7. On day 0 subsets underwent intraoperative determination of renal blood flow (n = 35) by Doppler flow meter and E(PAH) (n = 25) by renal venous assay. Blood flow was also determined in another subset of 16 recipients on postoperative day 7 by phase contrast-cine-magnetic resonance imaging, and E(PAH) was computed from the simultaneous PAH clearance. Glomerular filtration rate (GFR) on day 7 was used to divide subjects into recovering (n = 23) and sustained (n = 21) acute renal failure (ARF) groups, respectively. Despite profound depression of GFR in the sustained ARF group, renal plasma flow was only slightly depressed, averaging 296 +/- 162 ml. min(-1). 1.73 m(-2) on day 0 and 202 +/- 72 ml. min(-1). 1.73 m(-2) on day 7, respectively. These values did not differ from corresponding values in the recovering ARF group: 252 +/- 133 and 280 +/- 109 ml. min(-1). 1.73 m(-2), respectively. E(PAH) was profoundly depressed on day 0, averaging 18 +/- 14 and 10 +/- 7% in recovering and sustained ARF groups, respectively, vs. 86 +/- 6% in normal controls (P < 0.001). Corresponding values on day 7 remained significantly depressed at 65 +/- 20 and 11 +/- 22%, respectively. We conclude that postischemic injury to the renal allograft results in profound impairment of E(PAH) that persists for at least 7 days, even after the onset of recovery. An ensuing reduction in urinary PAH clearance results in a gross underestimate of renal plasma flow, which is close to the normal range in the initiation, maintenance, and recovery stages of this injury.

    View details for Web of Science ID 000081923400019

    View details for PubMedID 10444587

  • Unenhanced CT in the evaluation of urinary calculi: Application of advanced computer methods SEMINARS IN ULTRASOUND CT AND MRI Olcott, E. W., Sommer, F. G. 1999; 20 (2): 136-141


    Recent advances in computer hardware and software technology enable radiologists to examine tissues and structures using three-dimensional figures constructed from the multiple planar images acquired during a spiral CT examination. Three-dimensional CT techniques permit the linear dimensions of renal calculi to be determined along all three coordinate axes with a high degree of accuracy and enable direct volumetric analysis of calculi, yielding information that is not available from any other diagnostic modality. Additionally, three-dimensional techniques can help to identify and localize calculi in patients with suspected urinary colic.

    View details for Web of Science ID 000079764600008

    View details for PubMedID 10222520

  • Sonography of intraabdominal gas collections AMERICAN JOURNAL OF ROENTGENOLOGY Pattison, P., Jeffrey, R. B., Mindelzun, R. E., Sommer, F. G. 1997; 169 (6): 1559-1564

    View details for Web of Science ID A1997YH01000018

    View details for PubMedID 9393165

  • Lesion contrast enhancement in medical ultrasound imaging IEEE TRANSACTIONS ON MEDICAL IMAGING Stetson, P. F., Sommer, F. G., Macovski, A. 1997; 16 (4): 416-425


    Methods for improving the contrast-to-noise ratio (CNR) of low-contrast lesions in medical ultrasound imaging are described. Differences in the frequency spectra and amplitude distributions of the lesion and its surroundings can be used to increase the CNR of the lesion relative to the background. Automated graylevel mapping is used in combination with a contrast-weighted form of frequency-diversity speckle reduction. In clinical studies, the techniques have yielded mean CNR improvements of 3.2 dB above ordinary frequency-diversity imaging and 5.6 dB over sharper conventional images, with no post-processing graylevel mapping.

    View details for Web of Science ID A1997XP72500006

    View details for PubMedID 9262999

  • Accuracy of detection and measurement of renal calculi: In vitro comparison of three-dimensional spiral CT, radiography, and nephrotomography RADIOLOGY Olcott, E. W., Sommer, F. G., Napel, S. 1997; 204 (1): 19-25


    To compare accuracy of three-dimensional (3D) spiral computed tomography (CT) performed without administration of contrast material with that of radiography and linear nephrotomography in detection and measurement of renal calculi.Fifty renal calculi within an abdominal phantom were imaged with 3D spiral CT, radiography, and linear nephrotomography. Spiral CT data were analyzed with workstation-based 3D imaging software, with a thresholding procedure based on the maximally attenuating voxel within each calculus during measurement. Measurement accuracy and detection rates were compared according to modality. Conventional and magnification-corrected measurements from radiography and linear nephrotomography were included.Spiral CT depicted calculi and allowed determination of the collective two-dimensional and 3D linear measurements statistically significantly more accurately than the other techniques; the mean linear measurement errors along individual axes did not exceed 3.6%. With 3D spiral CT, calculus volumes were determined with a mean error of -4.8%.3D spiral CT enabled highly accurate determination of the volumes and all three linear dimensions of renal calculi. In addition, 3D spiral CT depicted calculi more sensitively than traditional techniques and provided new information and improved accuracy in the evaluation of nephrolithiasis.

    View details for Web of Science ID A1997XF19400008

    View details for PubMedID 9205217

  • Non-contrast spiral CT for patients with suspected renal colic EUROPEAN RADIOLOGY Katz, D. S., Lane, M. J., Sommer, F. G. 1997; 7 (5): 680-685


    Renal colic, defined as acute flank pain caused by the passage of a ureteral calculus, is a common condition, but the correct diagnosis may not be apparent clinically. For decades, intravenous urography has been the test of choice for evaluating patients with suspected renal colic. Recently, unenhanced (non-contrast) helical CT has been shown to be an accurate and highly effective examination which can be used instead of intravenous urography. In this article, the technique is reviewed in detail, including its advantages and potential pitfalls.

    View details for Web of Science ID A1997XE74200008

    View details for PubMedID 9166565

  • Volume rendering of CT data: Applications to the genitourinary tract AMERICAN JOURNAL OF ROENTGENOLOGY Sommer, F. G., Olcott, E. W., Chen, I., Beaulieu, C. F. 1997; 168 (5): 1223-1226

    View details for Web of Science ID A1997WV56800017

    View details for PubMedID 9129415

  • Tissue ablation using an acoustic waveguide for high-intensity focused ultrasound MEDICAL PHYSICS Sommer, F. G., Sumanaweera, T. S., Glover, G. 1997; 24 (4): 537-538


    High-intensity focused ultrasound (HIFU) has been shown capable of selective tissue destruction in humans, with promise as a tool for ablation of tumors, although one practical problem is reflection of sound at gas or bony interfaces within the body. We evaluated a water-filled cylindrical metal tube as a waveguide for HIFU, since such a general technique might be useful for ablation of otherwise inaccessible tumors in the body. Our studies indicate that such a waveguide is capable of propagating HIFU from a piezoelectric source, with resultant heating of tissue specimens to greater than 80 degrees C, causing focal tissue destruction.

    View details for Web of Science ID A1997WU28400008

    View details for PubMedID 9127305

  • Angiographic imaging with 2D RF pulses MAGNETIC RESONANCE IN MEDICINE Alley, M. T., Pauly, J. M., Sommer, F. G., Pelc, N. J. 1997; 37 (2): 260-267


    Magnetic resonance angiography (MRA) was performed by using RF pulses designed to excite a limited spatial extent in two orthogonal directions. The restriction in the second spatial dimension can be used to increase inflow enhancement and to improve small field-of-view imaging. A rectangular excitation was produced with an "echo-planar" k-space trajectory and a sinc-modulated RF waveform. In vivo images have demonstrated that vessels are more clearly delineated with the two-dimensional excitation. Aliasing artifacts in small field-of-view imaging are significantly reduced, although in some cases complete elimination is not possible due to the nature of the gradient trajectory.

    View details for Web of Science ID A1997WD27200016

    View details for PubMedID 9001151

  • Unenhanced helical CT of ureteral stones: Incidence of associated urinary tract findings AMERICAN JOURNAL OF ROENTGENOLOGY Katz, D. S., Lane, M. J., Sommer, F. G. 1996; 166 (6): 1319-1322


    The objective of this study was to determine the incidence of urinary tract findings associated with ureteral stones on unenhanced helical CT scans of patients with acute renal colic.One hundred forty-one consecutive patients with suspected renal colic were referred by the emergency department for a helical CT scan that was obtained without oral or IV contrast. The CT scans of 54 of these patients were interpreted as positive for ureteral calculi, and these CT scans were reviewed retrospectively. The size and location of each ureteral calculus and of any concurrent urinary tract calculi were recorded. The presence or absence of hydronephrosis, hydroureter, perinephric edema or soft-tissue stranding, and periureteral edema was also noted.We reviewed the original 5-mm axial images from the 54 CT scans. Calculi were present in the proximal, mid, and distal ureter in eight, four, and 14 patients respectively, and at the ureterovesicular junction in 28 patients. Only two patients had more than one ureteral calculus, and none had a contralateral ureteral calculus. Concurrent renal parenchymal and/or nonobstructing calculi in the renal pelvis were seen in five patients with proximal, mid, or distal ureteral stones and in 16 patients with ureterovesicular junction stones. Hydronephrosis was found in 37 patients, hydroureter in 36 patients, and perinephric soft-tissue changes in 35 patients. Periureteral edema could not be evaluated in the 28 patients with ureterovesicular junction calculi because of the adjacent bladder, but periureteral edema was clearly seen immediately adjacent to the ureteral stone in 17 of the other 26 patients. Only two of the 54 patients had no evidence of hydronephrosis, hydroureter, or perinephric soft-tissue changes.In patients with ureteral calculi imaged with unenhanced CT for acute renal colic, associated findings included hydronephrosis, hydroureter, perinephric soft-tissue changes, and periureteral edema. These common findings provided supportive evidence that an acute obstructive process was present.

    View details for Web of Science ID A1996UM26100019

    View details for PubMedID 8633440



    The purpose of this study was to determine the value of reformatted noncontrast helical CT in patients with suspected renal colic. We hoped to determine whether this technique might create images acceptable to both radiologists and clinicians and replace our current protocol of sonography and abdominal plain film.Thirty-four consecutive patients with signs and symptoms of renal colic were imaged with both noncontrast helical CT and a combination of plain film of the abdomen and renal sonography. Reformatting of the helical CT data was performed on a workstation to create a variety of reformatted displays. The correlative studies were interpreted by separate blinded observers. Clinical data, including the presence of hematuria and the documentation of stone passage or removal, were recorded.Findings on 18 CT examinations were interpreted as positive for the presence of ureteral calculi; 16 of these cases were determined to be true positives on the basis of later-documented passage of a calculus. Thirteen of the 16 cases proved to be positive were interpreted as positive for renal calculi using the combination of abdominal plain film and renal sonography. The most useful CT reformatting technique was curved planar reformatting of the ureters to determine whether a ureteral calculus was present.In this study, noncontrast helical CT was a rapid and accurate method for determining the presence of ureteral calculi causing renal colic. The reformatted views produced images similar in appearance to excretory urograms, aiding greatly in communicating with clinicians. Limitations on the technique include the time and equipment necessary for reformatting and the suboptimal quality of reformatted images when little retroperitoneal fat is present.

    View details for Web of Science ID A1995RQ00600003

    View details for PubMedID 7645461

  • CINE SPIRAL IMAGING MAGNETIC RESONANCE IN MEDICINE Liao, J. R., Sommer, F. G., Herfkens, R. J., Pelc, N. J. 1995; 34 (3): 490-493


    Interleaved spiral scanning of k-space is an efficient and fast method for imaging dynamic processes. In this article, a cine version of interleaved spiral imaging is presented. The method is shown to overcome the "lightning-flash" artifacts of the conventional triggered (gated) method. Compared with the segmented k-space 2DFT method, it achieves better temporal resolution in a comparable or shorter scan time. Preliminary human studies show that the method is a promising tool for imaging dynamic processes.

    View details for Web of Science ID A1995RR68700029

    View details for PubMedID 7500891

  • ASSESSMENT OF LIVING RENAL DONORS WITH SPIRAL CT RADIOLOGY Rubin, G. D., Alfrey, E. J., Dake, M. D., Semba, C. P., Sommer, F. G., Kuo, P. C., Dafoe, D. C., WASKERWITZ, J. A., Bloch, D. A., Jeffrey, R. B. 1995; 195 (2): 457-462


    To determine whether spiral computed tomography (CT) can be used to evaluate potential living renal donors.Twelve potential living renal donors underwent spiral CT and conventional arteriography. CT angiography was performed with 30-second spiral acquisition during injection of 150 mL of nonionic iodinated contrast material into an antecubital vein at 5 mL/sec. Five minutes after injection, a frontal abdominal scout projection was obtained to assess the renal collecting system. Results of blinded interpretations of axial CT angiograms, three-dimensional CT angiograms, and conventional arteriograms were correlated with intraoperative findings in 11 cases.Axial and three-dimensional CT angiography were 100% sensitive for identifying seven accessory renal arteries and 14% and 93% sensitive for identifying five prehilar renal artery branches. Renal venous anomalies were confirmed in three patients at surgery. Operative management changed in four of 11 patients who underwent donor nephrectomy.Spiral CT holds promise as a single examination for anatomic assessment of living renal donors.

    View details for Web of Science ID A1995QU71700028

    View details for PubMedID 7724766

  • QUANTITATIVE MAGNETIC-RESONANCE FLOW IMAGING MAGNETIC RESONANCE QUARTERLY Pelc, N. J., Sommer, F. G., Li, K. C., Brosnan, T. J., Herfkens, R. J., Enzmann, D. R. 1994; 10 (3): 125-147


    Time-of-flight and phase shift methods have both been used for vascular imaging with magnetic resonance. Phase methods, and phase contrast in particular, are well suited to quantitative measurements of velocity and volume flow rate. The most robust methods for measuring flow encode through-plane velocity into phase shift and compute flow by integrating the measured velocity over the vessel lumen. The accuracy of the flow data can be degraded by the effects of acceleration and eddy currents and by partial volume effects, including the effects of finite slice thickness and resolution, pulsatile waveforms, motion, and chemical shift. The reproducibility depends on the signal-to-noise of the data and the strength of the flow encoding and can be degraded by inconsistent definition of the vessel boundary. The adjustable flow sensitivity inherent in this method is a particular asset, allowing phase contrast flow measurement to operate over a dynamic range exceeding 10(5). Recently developed rapid imaging methods are helpful in applications that would be compromised by respiratory motion. With care, excellent quantitative data can be quickly obtained in vivo, and the resulting flow information is valuable for the diagnosis and management of a variety of conditions.

    View details for Web of Science ID A1994PM96800001

    View details for PubMedID 7811608



    Graded compression color Doppler sonography was used to evaluate gastrointestinal blood flow in 20 normal fasting subjects and 32 patients with focal gastrointestinal lesions. Imaging was optimized for color sensitivity using a 5 MHz linear array transducer. Criteria were established for normal mural blood flow based on findings in normal controls. Two reviewers blinded to the final diagnosis compared patterns of mural vascularity in normal and abnormal patients. Increased mural blood flow was demonstrated in all 32 patients with gastrointestinal inflammatory disorders and in seven of nine patients with neoplasms. No mural flow was demonstrated in four patients with small bowel infarction. The greatest overall degree of flow was noted in patients with Crohn's disease and cytomegalovirus colitis. Flow in tumors was variable, ranging from strikingly increased flow in a giant villoglandular polyp to absent flow in a metastasis from lung carcinoma. Our preliminary experience suggests that the presence of considerable overlap in the color Doppler patterns of mural blood flow in inflammatory and neoplastic lesions. Color Doppler sonography alone without spectral waveform analysis may not distinguish focal inflammatory from neoplastic disorders of the gastrointestinal tract reliably. However, this technique potentially may be useful in diagnosing small bowel ischemia when thickened segments of small bowel are identified with absent flow.

    View details for Web of Science ID A1994NP96200009

    View details for PubMedID 8083948



    There is at present no noninvasive method that reliably measures blood flow in the poorly functioning renal allograft. The present study was designed to evaluate phase-contrast cine magnetic resonance imaging (PC-cine-MRI) for this purpose. We recruited for study 18 patients who had received kidney transplants 13-66 months earlier from closely related living donors. As judged by the glomerular filtration rate, which was elevated for a single kidney (76 +/- 4 ml/min 1.73 m2), allograft function was excellent, permitting the assumption of unimpaired renal extraction of paminohippuric acid (PAH). Allograft blood flow was determined consecutively on the same day, first by the standard PAH clearance technique and they by the product of the velocity of protons and renal vein cross-sectional area using PC-cine-MRI. MRI determinations could not be completed because of claustrophobia in two patients and failure to image the terminus of the allograft vein another two. Comparison of blood flow in the remaining 14 subjects revealed the two techniques to be strongly related (r = 0.91, P < 0.001). On the average, the renal blood flow rate was similar by each method; 732 +/- 62 by PAH clearance and 703 +/- 69 ml/min by PC-cine-MRI, but the agreement among individuals between the two methods was only modest, with a 95% confidence interval of agreement from -214 to +254 ml/min. We conclude that PC-cine-MRI provides a fairly accurate and noninvasive method for determining the rate of blood flow in the transplanted kidney. With further refinement it should permit the role of depressed blood flow in a variety of acute and chronic forms of human allograft dysfunction to be elucidated in humans for the first time.

    View details for Web of Science ID A1994NP05700007

    View details for PubMedID 8197605

  • RENAL-ARTERY BLOOD-FLOW - QUANTITATION WITH PHASE-CONTRAST MR-IMAGING WITH AND WITHOUT BREATH-HOLDING RADIOLOGY Debatin, J. F., Ting, R. H., WEGMULLER, H., Sommer, F. G., Fredrickson, J. O., Brosnan, T. J., BOWMAN, B. S., Myers, B. D., Herfkens, R. J., Pelc, N. J. 1994; 190 (2): 371-378


    To compare the accuracy of 16-frame cine phase-contrast (PC) magnetic resonance (MR) imaging with those of two breath-hold PC techniques in the measurement of renal artery blood flow.In vitro flow measurements were performed in a segment of harvested human artery embedded in gel. For the cine PC acquisition, respiratory motion was simulated. In eight subjects with recently obtained para-amino-hippurate-clearance renal blood flow data, renal artery flow measurements were subsequently performed with two breath-hold imaging techniques and with cine PC imaging during shallow respiration.Breath-hold sequences were significantly more accurate than conventional cine PC sequences both in vitro (P < .005) and in vivo (P < .05). Cine PC imaging tended to overestimate flow (in vivo mean, 24.47% +/- 9.94), reflecting artifactual enlargement of the apparent vessel size.Reliable blood flow measurements in the renal artery are possible with breath-hold PC MR imaging.

    View details for Web of Science ID A1994MW44400017

    View details for PubMedID 8284383

  • SPIRAL CT OF RENAL-ARTERY STENOSIS - COMPARISON OF 3-DIMENSIONAL RENDERING TECHNIQUES RADIOLOGY Rubin, G. D., Dake, M. D., Napel, S., Jeffrey, R. B., McDonnell, C. H., Sommer, F. G., Wexler, L., Williams, D. M. 1994; 190 (1): 181-189


    To evaluate the accuracy of computed tomographic (CT) angiography in the detection of renal artery stenosis (RAS).CT angiography was performed in 31 patients undergoing conventional renal arteriography. CT angiographic data were reconstructed with shaded surface display (SSD) and maximum-intensity projection (MIP). Stenosis was graded with a four-point scale (grades 0-3). The presence of mural calcification, poststenotic dilatation, and nephrographic abnormalities was also noted.CT angiography depicted all main (n = 62) and accessory (n = 11) renal arteries that were seen at conventional arteriography. MIP CT angiography was 92% sensitive and 83% specific for the detection of grade 2-3 stenoses (> or = 70% stenosis). SSD CT angiography was 59% sensitive and 82% specific for the detection of grade 2-3 stenoses. The accuracy of stenosis grading was 80% with MIP and 55% with SSD CT angiography. Poststenotic dilatation and the presence of an abnormal nephrogram were 85% and 98% specific, respectively.CT angiography shows promise in the diagnosis of RAS. The accuracy of CT angiography varies with the three-dimensional rendering technique employed.

    View details for Web of Science ID A1994MW25300036

    View details for PubMedID 8259402



    The size of prostatic carcinomas, as determined by estimations of the tumor volume, has a direct correlation with the histologic grade and stage. Therefore, accurate information about tumor volume can play an important role in determining appropriate treatment and establishing a patient's prognosis. Accordingly, we performed a study to assess the accuracy of MR imaging with external-array coils and the fast spin-echo technique for determining tumor volume in patients with prostatic cancer.In a prospective study, 20 patients with biopsy-proved prostatic cancer had MR imaging before radical prostatectomy. A 1.5-T system, a prototype external-array coil, and fast spin-echo technique were used to obtain axial T2-weighted (4000/120 [TR/TE]) MR images throughout the prostate and seminal vesicles. Contiguous 5-mm sections were obtained with a 256 x 256 or 256 x 192 matrix, 24-cm field of view, four excitations, and fat suppression. The volumes of cancer obtained with MR imaging and surgical specimens were determined independently. The areas of tumor were determined from individual axial sections by summing and multiplying by the section thickness.Seventeen of the 20 cancers were detected on MR images. A significant correlation between the volume of the tumor as determined with MR imaging and measurements of the specimens was observed (r = .81, p < .001). Four transition zone tumors were detected as zones of rather homogeneous decreased intensity. One important source of error for volumes determined with MR images was a limitation in the histologic specificity of MR imaging for the delineation of cancer; in some cases benign changes or normal prostates were interpreted as cancer. Another limitation was the presence of changes after biopsy that concealed portions of 10 of the 17 tumors visualized.The accuracy of the MR technique used was not sufficient for reliable prediction of tumor volume. The lack of specificity of T2-weighted MR imaging for cancer detection and the presence of changes caused by biopsy were major sources of error.

    View details for Web of Science ID A1993LW01500018

    View details for PubMedID 8517328



    Fourteen adult patients with clinically suspected AAC and inconclusive initial sonograms underwent follow-up sonography within 24 hours. Eight patients had initial studies demonstrating a normal thickness of the gallbladder wall. Four of these patients demonstrated progressive thickening of the gallbladder wall on follow-up scans and were diagnosed as having AAC. In three of these patients AAC was proved at surgery, and the remaining patient improved clinically after percutaneous cholecystostomy. Four other patients with normal gallbladder wall thickness on both the initial and follow-up sonograms had benign clinical follow-up results without evidence of AAC. The remaining six patients had a thickened gallbladder on the initial sonogram. In one of these patients, the gallbladder wall thickening resolved on follow-up sonography. In the remaining five patients the gallbladder wall thickening did not change. Four of these patients had benign follow-up results but one patient was found to have AAC at surgery. Follow-up sonography may be helpful to confirm AAC if there is progressive edema of the gallbladder wall. A normal gallbladder wall on an initial study does not exclude early AAC. Thickening of the gallbladder wall on initial studies still remains a problem and other ancillary criteria must be used to establish the diagnosis of AAC.

    View details for Web of Science ID A1993KY03400001

    View details for PubMedID 8497021



    A system for the digitization and frequency spectral analysis of radiofrequency data for ultrasonic waveforms backscattered from abdominal tissues is described. Studies of phantoms meant to simulate abdominal tissues of differing scattering characteristics indicated that frequency spectral differences due to differences in the frequency dependence of backscattering were seen with 5 MHz probes, but not with a 3.5 MHz probe. Studies of a phantom with a simulated lesion of altered scattering characteristics indicated potential for improved lesion detection and characterization, using custom circuitry developed for variable bandwidth filtering of received ultrasonic beams. The techniques discussed have potential for improved diagnosis of diffuse and focal abdominal abnormalities over that obtained with conventional ultrasonic imaging.

    View details for Web of Science ID A1993KY03200004

    View details for PubMedID 8468741

  • GADOLINIUM-ENHANCED MRI OF THE ABNORMAL PROSTATE MAGNETIC RESONANCE IMAGING Sommer, F. G., Nghiem, H. V., Herfkens, R., McNeal, J. 1993; 11 (7): 941-948


    A prospective study of the use of a low osmolar gadolinium-based intravenous contrast material for MRI of the abnormal prostate was performed. Eight patients scheduled for prostatectomy, six with prostate cancer and two with benign prostatic hyperplasia (BPH), were imaged preoperatively on a 1.5 T system using a pelvic coil array and employing Gadodiamide (0.3 mmol/kg). T2-weighted fast-spin echo (FSE) imaging was also performed in the same axial planes employed for gadolinium-enhanced studies. Detailed pathologic correlation was performed for the six patients with carcinoma. While regions of BPH and cancer enhanced to a similar degree following intravenous contrast agent, BPH enhancement was more heterogeneous than cancer. No advantages in detecting prostate cancer, in differentiating cancer from BPH or normal prostatic tissue, or in assessing extra-prostatic spread of cancer were observed for the contrast-enhanced studies compared to T2-weighted FSE imaging.

    View details for Web of Science ID A1993MB03400005

    View details for PubMedID 7694028

  • THE PELVIS - T2-WEIGHTED FAST SPIN-ECHO MR-IMAGING RADIOLOGY Nghiem, H. V., Herfkens, R. J., Francis, I. R., Sommer, F. G., Jeffrey, R. B., Li, K. C., Steiner, R. M., Glover, G. H. 1992; 185 (1): 213-217


    Fast spin-echo (SE) T2-weighted magnetic resonance (MR) imaging provides images with highly T2-weighted contrast in substantially reduced imaging times. In a prospective evaluation, fast SE T2-weighted imaging of the pelvis was compared with conventional SE T2-weighted imaging in 30 consecutive patients in whom pelvic pathologic conditions were suspected. Three reviewers independently analyzed the images for (a) overall image quality, (b) pelvic organ definition, (c) conspicuity of pelvic fluid, and (d) conspicuity of pelvic pathologic conditions. Fast SE images were rated superior to conventional SE T2-weighted images in 60% (54 of 90) of the case reviews for overall image quality, in 69% (62 of 90) for pelvic organ definition, in 63% (57 of 90) for conspicuity of pelvic fluid, and in 68% (43 of 63) for conspicuity of pelvic pathologic conditions. The fast SE examinations were typically three to four times faster than conventional SE T2-weighted examinations. No pathologic findings seen on conventional SE T2-weighted images were undetected on fast SE images. Fast SE images may replace conventional SE T2-weighted images in MR imaging of the pelvis.

    View details for Web of Science ID A1992JN60800039

    View details for PubMedID 1523311



    Previous biochemical and 13C NMR spectroscopic data have suggested that the metabolism of citrate, a secretory product of normal prostate, may be interrupted in prostate cancer. In the present study in vitro 1H NMR spectroscopy was used to see if cell strains derived from prostate cancers could be reliably distinguished from those of normal prostate epithelium. High-resolution one-dimensional and two-dimensional J-resolved 1H NMR spectra as well as gas chromatography coupled with mass spectroscopy were used to study extracts of highly defined cell strains from normal peripheral zone, normal central zone, adenocarcinoma, and benign prostatic hyperplasia. Resonances assigned to citric acid and related metabolites were identified. Cell strains derived from prostate cancers tended to have smaller amounts of citrate than those from normal prostate epithelium. However, the differences were small and not statistically significant. The lack of statistically significant differences may reflect the variability present in both normal and abnormal cell strains and thus underscore the well-known difficulty in differentiating normal and cancerous tissues.

    View details for Web of Science ID A1991FQ24300033

    View details for PubMedID 1715505



    The authors describe the use of duplex and/or color Doppler ultrasonography of the pelvis in three women to demonstrate the presence of venous malformations. One patient with a pulsatile vaginal mass was shown to have an arteriovenous malformation of the vaginal wall. The second patient was shown to have an unsuspected venous angioma in the endometrial cavity. The third patient was shown to have adnexal varices that closely mimicked hydrosalpinx. In the latter two cases, the duplex and color flow capabilities of an endovaginal probe were especially important.

    View details for Web of Science ID A1991EU03500049

    View details for PubMedID 1987622



    A preliminary study was performed to evaluate the effectiveness of narrow-band filtration of backscattered ultrasound for the detection of splenic involvement in patients with Hodgkin disease. Regions of interest were identified in the spleens of 14 normal volunteers and eight Hodgkin disease patients before staging laparotomy. An analysis of the narrow-band-filtered waveforms showed that the mean amplitudes of the filtered ultrasonic signals received correlated with the presence of extensive splenic involvement with Hodgkin disease (defined as more than four grossly visible nodules on cut section) (p = .0004). Conversely, mean amplitudes of unfiltered ultrasonic backscatter, employed in conventional sonographic imaging, did not correlate with splenic involvement (p = .5). Phantom studies were performed to develop a tissue model for the observed phenomena; images of the phantoms and of the involved and uninvolved spleens were made by using techniques involving narrow-band filtration of backscattered ultrasound. Our results indicate that narrow-band-filtered sonography holds promise for detecting lymphomatous involvement of the spleen, although larger studies, with equipment allowing real-time implementation of narrow-band filtering, are needed.

    View details for Web of Science ID A1989U668700011

    View details for PubMedID 2655388

  • NOISE-REDUCTION IN MAGNETIC-RESONANCE IMAGING MAGNETIC RESONANCE IN MEDICINE Brosnan, T., Wright, G., Nishimura, D., Cao, Q. H., Macovski, A., Sommer, F. G. 1988; 8 (4): 394-409


    This paper describes a noise-reduction technique applicable to multiple-measurement systems. This method, known as measurement-dependent filtering (or MDF), can be used to advantage in a number of MRI applications. We present the general theory for one of these applications, material-canceled projection imaging. We discuss and show the results of MDF for material-canceled images as well as for heavily T2-weighted spin-echo images and computed T2 images. Significant improvements in SNR are demonstrated while spatial resolution is preserved.

    View details for Web of Science ID A1988R338200003

    View details for PubMedID 3231068

  • THE ABNORMAL PROSTATE - MR IMAGING AT 1.5 T WITH HISTOPATHOLOGIC CORRELATION RADIOLOGY Carrol, C. L., Sommer, F. G., McNeal, J. E., Stamey, T. A. 1987; 163 (2): 521-525


    Thirteen patients with biopsy-proved adenocarcinoma were prospectively examined with magnetic resonance (MR) imaging with use of a 1.5-T superconducting magnet. All patients subsequently underwent radical prostatectomy and careful, axial, histologic mapping of prostatic disease. Histologic findings were recorded on serial, axial diagrams to ensure precise pathologic correlation with the MR images. MR permitted identification of eight of 12 (67%) adenocarcinomas as hypointense foci (relative to the surrounding, higher intensity, peripheral zone); but tumor volume was under-estimated with MR imaging in five of eight cases (63%). Nodules of prostatic hyperplasia were identified correctly in only one of nine patients (11%). These findings suggest that, despite that fact that high field strength MR imaging currently does not depict all pathologic foci within the prostate, it may be of predictive value in the differential diagnosis of prostatic abnormalities when their locations are demonstrable.

    View details for Web of Science ID A1987G924000044

    View details for PubMedID 2436253