Lawrence C. Chow

All Publications

• Complication to consider: delayed traumatic hemothorax in older adults Trauma Surgery Acute Care Open Choi, J., Anand, A., Sborov, K. D., Walton, W., Chow, L., Guillamondegui, O., Dennis, B. M., Spain, D., Staudenmayer, K. 2021

  View details for DOI 10.1136/tsaco-2020-000626

• Using Online Survey Software to Enhance Radiology Learning. Academic radiology Kelahan, L. n., Cheng, S. N., Kagoma, Y. K., Horowitz, J. M., Miller, F. H., Guo, H. H., Chow, L. n. 2020

  Abstract

  Online educational modules can augment radiology learning by creating opportunities to interact with images in more dynamic ways than with static presentation of images in lectures or journal articles. Building these modules on an online survey platform allows for quantitative assessment and learner feedback, without requiring programming knowledge or need for new website creation.Interactive online tutorials were built on a web-based survey platform (Qualtrics, Provo, Utah) accessible by computer or mobile device to teach radiology imaging findings of selected high-morbidity diagnoses. Topics included congenital-type internal hernias (module 1), acute appendicitis in the pregnant patient (module 2), and unintentionally retained surgical instruments (RSI; module 3). Modules consisted of pretest, educational module, and post-test components. For modules 1 and 2, graphics interchange formats were utilized to show CT and MRI image stacks for the diagnosis of congenital-type internal hernias and acute appendicitis in pregnant patients, respectively. For module 3, the "Heat Map" format was chosen to showcase intraoperative radiograph cases, which allowed participants to click on the potential RSI in the image. Pre- and post-test scores were evaluated. To determine statistical significance, an alpha level of 0.05 was utilized.Module 1 (Internal Hernia): Twenty-one radiology trainees completed the module. The mean pretest score was 3.66 (±1.13) points out of a total 6 possible points (61%), compared to 4.52 (±1.03) points on the post-test (75%). This was a statistically significant increase on the post-test of 0.87 points (95% CI [confidence interval] 0.36, 1.38), t(20) = 3.53, p= 0.002. Module 2 (MR Appendicitis): Seventeen radiology trainees completed the module. The mean pretest score was 3.18 (±1.42) points out of a total 6 possible points (53%), compared to 5.12 (±0.86) points on the post-test (85%). This was a statistically significant increase on the post-test of 1.94 points (95% CI 1.12, 2.76), t(16) = 5.00, p< 0.001. Module 3 (RSI): One hundred seven participants completed the module. The mean pretest score was 3.60 (±1.53) points out of a total 6 possible points (60%), compared to 4.54 (±1.36) points on the post-test (76%). This was a statistically significant increase on the post-test of 0.94 points (95% CI 0.67, 1.21), t(106) = 6.84, p< 0.001.An online survey platform can be used to build interactive education modules. Post-test scores significantly improved from pretest scores with these educational modules.

  View details for DOI 10.1016/j.acra.2020.08.032

  View details for PubMedID 32972839

• A review of internal hernias related to congenital peritoneal fossae and apertures. Abdominal radiology (New York) Kelahan, L. n., Menias, C. O., Chow, L. n. 2020

  Abstract

  Congenital-type internal hernias have the potential to cause small bowel obstruction well into adulthood. Congenital-type internal hernias include left paraduodenal, right paraduodenal, foramen of Winslow, pericecal, sigmoid mesocolon, transomental, small bowel mesentery, and broad ligament hernias. This review summarizes CT imaging features and complications of congenital internal hernias using a systematic approach based on abdominopelvic quadrants and key anatomic features. CT imaging will continue to be commonly used to evaluate abdominal pain. Anatomical landmarks and characteristic CT findings can help identify congenital internal hernias as a potential cause of abdominal pain.

  View details for DOI 10.1007/s00261-020-02829-4

  View details for PubMedID 33128101

• Pitfalls in MDCT urography APPLIED RADIOLOGY Moore, R., Harvin, H., Chow, L. 2018; 47 (12): 16–21

  View details for Web of Science ID 000451976100003

• Mullerian Duct Anomalies: Embryological Development, Classification, and MRI Assessment JOURNAL OF MAGNETIC RESONANCE IMAGING Robbins, J. B., Broadwell, C., Chow, L. C., Parry, J. P., Sadowski, E. A. 2015; 41 (1): 1–12

  Abstract

  Müllerian duct anomalies (MDA) occur due to abnormal development of the uterus, cervix, and vagina, many times affecting a woman's ability to conceive and carry a pregnancy to term. The spectrum of possible abnormalities are related to the development of two separate Müllerian systems, which then fuse and subsequently undergo degeneration of the fused segments. This multiphasic development explains the multiple variations within the scheme of MDA classification. The purpose of this article is to review the embryologic development of the Müllerian ducts, relate the development to the most commonly used classification system, and review the magnetic resonance imaging (MRI) assessment of Müllerian duct anomalies. A brief review of the treatment options, as they relate to the imaging diagnosis, will be provided as well.

  View details for DOI 10.1002/jmri.24771

  View details for Web of Science ID 000346427800001

  View details for PubMedID 25288098

• MRI of Pregnancy-Related Issues: Mullerian Duct Anomalies AMERICAN JOURNAL OF ROENTGENOLOGY Robbins, J. B., Parry, J., Guite, K. M., Hanson, M. E., Chow, L. C., Kliewer, M. A., Sadowski, E. A. 2012; 198 (2): 302–10

  Abstract

  Müllerian duct anomalies can adversely affect pregnancy outcomes and can result in clinical symptoms. This article will review the appropriate management of patients with müllerian duct abnormalities.Whereas uterine and vaginal septa, vaginal agenesis, and unicornuate uterus can be managed surgically, other uterine anomalies tend to be managed clinically. Hence, appropriate management depends on a reliable assessment of pelvic anatomy. MRI can accurately display female pelvic anatomy and is, therefore, useful in guiding therapy.

  View details for DOI 10.2214/AJR.11.7789

  View details for Web of Science ID 000300296600025

  View details for PubMedID 22268172

• Computer-aided detection (CAD) of lung nodules in CT scans: radiologist performance and reading time with incremental CAD assistance EUROPEAN RADIOLOGY Roos, J. E., Paik, D., Olsen, D., Liu, E. G., Chow, L. C., Leung, A. N., Mindelzun, R., Choudhury, K. R., Naidich, D. P., Napel, S., Rubin, G. D. 2010; 20 (3): 549-557

  Abstract

  The diagnostic performance of radiologists using incremental CAD assistance for lung nodule detection on CT and their temporal variation in performance during CAD evaluation was assessed.CAD was applied to 20 chest multidetector-row computed tomography (MDCT) scans containing 190 non-calcified > or =3-mm nodules. After free search, three radiologists independently evaluated a maximum of up to 50 CAD detections/patient. Multiple free-response ROC curves were generated for free search and successive CAD evaluation, by incrementally adding CAD detections one at a time to the radiologists' performance.The sensitivity for free search was 53% (range, 44%-59%) at 1.15 false positives (FP)/patient and increased with CAD to 69% (range, 59-82%) at 1.45 FP/patient. CAD evaluation initially resulted in a sharp rise in sensitivity of 14% with a minimal increase in FP over a time period of 100 s, followed by flattening of the sensitivity increase to only 2%. This transition resulted from a greater prevalence of true positive (TP) versus FP detections at early CAD evaluation and not by a temporal change in readers' performance. The time spent for TP (9.5 s +/- 4.5 s) and false negative (FN) (8.4 s +/- 6.7 s) detections was similar; FP decisions took two- to three-times longer (14.4 s +/- 8.7 s) than true negative (TN) decisions (4.7 s +/- 1.3 s).When CAD output is ordered by CAD score, an initial period of rapid performance improvement slows significantly over time because of non-uniformity in the distribution of TP CAD output and not to a changing reader performance over time.

  View details for DOI 10.1007/s00330-009-1596-y

  View details for Web of Science ID 000274544800005

  View details for PubMedID 19760237

• Split-bolus MDCT urography with synchronous nephrographic and excretory phase enhancement AMERICAN JOURNAL OF ROENTGENOLOGY Chow, L. C., Kwan, S. W., Olcott, E. W., Sommer, G. 2007; 189 (2): 314-322

  Abstract

  Our purpose was to evaluate the utility of CT urography performed using a split contrast bolus that yields synchronous nephrographic and excretory phase enhancement.Five hundred consecutive patients referred for evaluation of possible urinary tract abnormalities (327 for painless hematuria) underwent CT urography with unenhanced scanning of the abdomen and pelvis and scanning during concurrent nephrographic and excretory phase enhancement produced by administration of a split contrast bolus. The enhanced abdomen scan was obtained with abdominal compression; the enhanced pelvis scan was obtained after release of compression. Findings from axial sections and coronal maximum intensity projections were correlated with clinical follow-up and, as available, with laboratory and other imaging studies including cystoscopy, ureteroscopy, urine cytology, surgery, and pathology. Follow-up management for each patient was determined by the clinical judgment of the referring physician.CT urography identified 100% of pathologically confirmed renal cell carcinomas (n = 10) and uroepithelial malignancies involving the renal collecting system or ureter (n = 8). An additional nine renal masses were identified for which no pathologic proof has yet been obtained, including eight subcentimeter solid renal masses and one multiloculated lesion. Fourteen of 19 confirmed cases of uroepithelial neoplasm involving the bladder were identified. CT urography yielded one false-positive for bladder tumor, two false-positives for ureteral tumor, and one patient with a bladder mass who refused further evaluation. CT urography yielded sensitivity and specificity of 100% and 99% and 74% and 99% and positive predictive value and negative predictive value of 80% and 100% and 93% and 99% for the renal collecting system and ureter and bladder, respectively. CT urography was ineffective in identifying 11 cases of noninfectious cystitis. CT urography also depicted numerous other congenital and acquired abnormalities of the urinary tract.Split-bolus MDCT urography detected all proven cases of tumors of the upper urinary tract, yielding high sensitivity and specificity. The split-bolus technique has the potential to reduce both radiation dose and the number of images generated by MDCT urography.

  View details for DOI 10.2214/AJR.07.2288

  View details for Web of Science ID 000248624400012

  View details for PubMedID 17646456

• Right Lower Quadrant Pain: Rule Out Appendicitis Ultrasound: A Practical Approach to Clinical Problems Chow, L., Jeffrey, R. B. Thieme Medical Publishers. 2007; 2nd
• Isolated fallopian tube torsion: A rare twist on a common theme AMERICAN JOURNAL OF ROENTGENOLOGY Gross, M., Blumstein, S. L., Chow, L. C. 2005; 185 (6): 1590-1592

  View details for DOI 10.2214/AJR.04.1646

  View details for Web of Science ID 000233510600033

  View details for PubMedID 16304018

• Vascular mapping of the leg with multi-detector row CT angiography prior to free-flap transplantation 87th Scientific Assembly and Annual Meeting of the Radiological-Society-of-North-America Chow, L. C., Napoli, A., Klein, M. B., Chang, J., Rubin, G. D. RADIOLOGICAL SOC NORTH AMERICA. 2005: 353–60

  Abstract

  To retrospectively evaluate multi-detector row computed tomographic (CT) angiography in determining donor- and recipient-site arterial suitability for successful vascularized free-flap transplantation.The institutional review board granted approval; informed consent was waived, and the study was HIPAA compliant. Lower extremities of 20 (12 male, eight female; mean age, 51 years; range, 10-84 years) patients undergoing vascularized free-flap procedures were examined at multi-detector row CT angiography. In five patients, legs were assessed as potential fibular free-flap donors for mandibular, maxillary, or radial reconstruction. In 15 patients, legs were assessed as recipient sites for free flaps. Vascular maps obtained with volume rendering, maximum intensity projections, and curved planar reformations were generated, and assessment was made in the depiction of calf vessels and presence of stenosis, occlusion, and anatomic anomaly. Findings of CT angiography, physical examination, and surgery were compared, where applicable, and successful CT-based prediction of the surgical intervention was assessed. Immediate and long-term (>70 days) viability of the graft was assessed in all patients.CT angiography depicted the entirety of all four major calf arteries in 29 of 32 legs scanned. In three legs, external-fixation hardware obscured some segments. There were no discrepancies between CT findings and those identified at the time of surgery. Arterial abnormalities, including stenosis, occlusion, and variant anatomy, were seen in 12 lower extremities in 10 patients. Only two were suspected on the basis of physical examination findings. In five of 20 patients, CT findings resulted in changes to the surgical plan. There was a 100% immediate viability of all grafts, which remained well vascularized between 70 days and 37 months after the procedure.Multi-detector row CT angiography provides a noninvasive means of preoperatively assessing lower extremity arteries for abnormalities, which could jeopardize graft viability or pedal arterial supply after free-flap procedures.

  View details for DOI 10.1148/radiol.2371040675

  View details for Web of Science ID 000231968000050

  View details for PubMedID 16100083

• Measurement of renal extraction fraction with contrast-enhanced CT RADIOLOGY Sommer, G., Olcott, E. W., Chow, L. C., Saket, R. R., Schraedley-Desmond, P. 2005; 236 (3): 1029-1033

  Abstract

  Study was approved by the institutional review board, and informed patient consent was waived. A method for minimization of sources of variability in measuring single-kidney extraction fraction (EF) was determined retrospectively with contrast material-enhanced computed tomography (CT). Ten adults underwent CT of the kidneys; precontrast scans were obtained, followed by postcontrast scanning 2 minutes after contrast material injection. Single-kidney EF was then calculated for each patient with the formula EF = (CT(A) - CT(V))/(CT(A) - CT(PRE)), where CT(A) and CT(V) are the postcontrast CT values (in Hounsfield units) of the systemic blood and renal venous blood, respectively, and CT(PRE) is the precontrast CT value of the blood. Both conventional two-dimensional and volumetric three-dimensional regions of interest were used for determining mean CT values of the blood. By using the volumetric regions of interest, left and right renal EF values averaged 17.3% and 18.0%, respectively, for two observers, compared with the accepted value of 15%-20%. This latter technique also minimized right-left kidney and interobserver variability in the measurement of EF.

  View details for DOI 10.1148/radiol.2363041371

  View details for Web of Science ID 000231412600039

  View details for PubMedID 16020561

• 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

  Abstract

  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

• The sonographic features of papillary thyroid carcinomas: pictorial essay. Ultrasound quarterly Jun, P., Chow, L. C., Jeffrey, R. B. 2005; 21 (1): 39-45

  Abstract

  Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy in children and adults, with an incidence of 22,000 cases per year in the United States. Differentiating PTC from more frequently occurring benign thyroid nodules has proved challenging as there may be significant overlap in their clinical presentation and sonographic appearance. That said, high-resolution ultrasound provides a safe and affordable way of identifying and characterizing thyroid nodules and guiding percutaneous biopsies. Although no single sonographic feature is pathognomonic for PTC, certain features should raise suspicion and the combination of several features may be even more suggestive. In this pictorial essay, we describe the high-resolution sonographic features of pathologically proven PTCs. The nodule number, echo texture, internal architecture, calcifications, margins, contours, vascularity, and lymph nodes are considered. While the classic sonographic description of PTC is a solitary, hypoechoic solid nodule with microcalcifications and intrinsic vascularity, in practice, PTC may manifest with a myriad of sonographic appearances making biopsy necessary for a definitive diagnosis.

  View details for PubMedID 15716757

• Pulmonary nodules on multi-detector row CT scans: Performance comparison of radiologists and computer-aided detection RADIOLOGY Rubin, G. D., Lyo, J. K., Paik, D. S., Sherbondy, A. J., Chow, L. C., Leung, A. N., Mindelzun, R., Schraedley-Desmond, P. K., Zinck, S. E., Naidich, D. P., Napel, S. 2005; 234 (1): 274-283

  Abstract

  To compare the performance of radiologists and of a computer-aided detection (CAD) algorithm for pulmonary nodule detection on thin-section thoracic computed tomographic (CT) scans.The study was approved by the institutional review board. The requirement of informed consent was waived. Twenty outpatients (age range, 15-91 years; mean, 64 years) were examined with chest CT (multi-detector row scanner, four detector rows, 1.25-mm section thickness, and 0.6-mm interval) for pulmonary nodules. Three radiologists independently analyzed CT scans, recorded the locus of each nodule candidate, and assigned each a confidence score. A CAD algorithm with parameters chosen by using cross validation was applied to the 20 scans. The reference standard was established by two experienced thoracic radiologists in consensus, with blind review of all nodule candidates and free search for additional nodules at a dedicated workstation for three-dimensional image analysis. True-positive (TP) and false-positive (FP) results and confidence levels were used to generate free-response receiver operating characteristic (ROC) plots. Double-reading performance was determined on the basis of TP detections by either reader.The 20 scans showed 195 noncalcified nodules with a diameter of 3 mm or more (reference reading). Area under the alternative free-response ROC curve was 0.54, 0.48, 0.55, and 0.36 for CAD and readers 1-3, respectively. Differences between reader 3 and CAD and between readers 2 and 3 were significant (P < .05); those between CAD and readers 1 and 2 were not significant. Mean sensitivity for individual readings was 50% (range, 41%-60%); double reading resulted in increase to 63% (range, 56%-67%). With CAD used at a threshold allowing only three FP detections per CT scan, mean sensitivity was increased to 76% (range, 73%-78%). CAD complemented individual readers by detecting additional nodules more effectively than did a second reader; CAD-reader weighted kappa values were significantly lower than reader-reader weighted kappa values (Wilcoxon rank sum test, P < .05).With CAD used at a level allowing only three FP detections per CT scan, sensitivity was substantially higher than with conventional double reading.

  View details for DOI 10.1148/radiol.2341040589

  View details for Web of Science ID 000225864800038

  View details for PubMedID 15537839

• Parallel imaging of the abdomen. Topics in magnetic resonance imaging Margolis, D. J., Bammer, R., Chow, L. C. 2004; 15 (3): 197-206

  Abstract

  Parallel imaging holds great potential for improving the quality of diagnostic abdominal MRI. The increased imaging speed afforded by parallel imaging can be translated into the obvious benefits of reduced scan time with set resolution and coverage, improved spatial resolution with set imaging time and coverage, increased anatomic coverage for a set imaging time and resolution, or some combination of the above. Additionally, the reduction in scan time can also allow some sequences that normally require multiple breath-holds to be performed with only one, or simply make breath-hold imaging possible for more patients. The decreased echo-train length allows for truer T2-weighting, less magnetic susceptibility artifact, and less blurring with echo-train imaging. Dynamic contrast-enhanced sequences can be acquired with improved temporal or spatial resolution. All of these potential advantages come with the trade-off of decreased signal-to-noise ratio, but for many patients, the benefits far outweigh the drawbacks and can vastly improve the diagnostic quality of abdominal MRI.

  View details for PubMedID 15480001

• Measurement of renal extraction fraction using contrast-enhanced computed tomography MEDICAL PHYSICS Sommer, G., Chow, L., Pelc, N. 2004; 31 (1): 37-38

  Abstract

  Renal extraction fraction (EF) is the percentage of plasma entering the glomerulus which is filtered. Contrast agents which are freely filtered and neither secreted nor reabsorbed, may be used as markers for renal filtration, allowing EF to be calculated from computed tomography (CT) measurements of systemic vessels and renal veins. CT scans of 10 adult patients having no known renal disease were studied in this manner, giving EF values averaging 12.6% and 12.3% for the right and left kidneys, respectively, compared to the accepted value of 15%-20%. EF measurement using CT may provide noninvasive evaluation of renal function, complementing CT-derived morphologic information.

  View details for DOI 10.1118/1.1631092

  View details for Web of Science ID 000188383500005

  View details for PubMedID 14761018

• Multidetector ct urography in clinical practice Applied Radiology Saket, R., Chow, L. 2004; 33: 22-32
• 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

  Abstract

  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

• Multidetector CT of pancreatic adenocarcinoma: diagnostic advances and therapeutic relevance EUROPEAN RADIOLOGY Prokesch, R. W., Schima, W., Chow, L. C., Jeffrey, R. B. 2003; 13 (9): 2147-2154

  Abstract

  Detection and staging of pancreatic malignancies remains a challenge for radiologists. Considering the poor prognosis of pancreatic adenocarcinoma, accurate preoperative staging is the key to a possibly curative surgical treatment. Contrast-enhanced helical CT has been the most commonly used for evaluation of pancreatic cancer in many institutions, although it suffers from many limitations. With the fast pace of advances in multidetector CT (MDCT), and the beginning clinical implementation of 16-row scanners, improvements in spatial resolution in the z-axis with near-isotropic imaging provide exquisite multiplanar reconstructions of pancreatic anatomy. This article provides an overview of current MDCT technique and protocols for assessment of pancreatic adenocarcinoma, and describes new 3D-display methods for effective visualization of large data sets provided by MDCT.

  View details for DOI 10.1007/s00330-003-1926-4

  View details for Web of Science ID 000185537700013

  View details for PubMedID 12819917

• Early experience with computed tomographic angiography in microsurgical reconstruction PLASTIC AND RECONSTRUCTIVE SURGERY Klein, M. B., Karanas, Y. L., Chow, L. C., Rubin, G. D., Chang, J. 2003; 112 (2): 498-503

  Abstract

  Preoperative angiography is frequently used in the planning of microsurgical reconstruction. However, several potentially devastating complications can result from angiography, including arterial occlusion and pseudoaneurysm. Computed tomographic angiography is a relatively new technique that can provide detailed information about vascular anatomy as well as soft and bony tissue without the risks of traditional angiography. In addition, three-dimensional image reconstruction uniquely demonstrates anatomical relationships among blood vessels, bones, and soft tissue. Fourteen computed tomographic angiograms were obtained in 10 patients undergoing microsurgical reconstruction of the head and neck, lower extremity, or upper extremity. The average patient age was 46.9 years (range, 22 to 67 years). Charges related to the computed tomographic procedure were compared with those of conventional preoperative imaging for microsurgical repair. At our institution, the average computed tomographic angiogram charge was 1140 US dollars, whereas the average charge for traditional arteriography was 3900 US dollars. When compared with intraoperative evaluation, computed tomographic angiograms demonstrated clinically relevant surgical anatomy. No complications were noted for the radiographic procedure or after free flap reconstruction. Computed tomographic angiography provides high-resolution, three-dimensional arterial, venous, and soft-tissue imaging without the risks of traditional angiogram and at a lower cost.

  View details for DOI 10.1097/01.PRS.0000070990.97274.FA

  View details for Web of Science ID 000184532700016

  View details for PubMedID 12900607

• Multidetector CT of the Urinary Tract Multidetector CT: Principles, Techniques and Clinical Applications Chow, L. C., Sommer, F. G. Lippincott, Williamsn & Wilkins. 2003
• Local staging of pancreatic carcinoma with multi-detector row CT: Use of curved planar reformations initial experience RADIOLOGY Prokesch, R. W., Chow, L. C., Beaulieu, C. F., Nino-Murcia, M., Mindelzun, R. E., Barnmer, R., Huang, J., Jeffrey, R. B. 2002; 225 (3): 759-765

  Abstract

  To evaluate the utility of curved planar reformations compared with standard transverse images in the assessment of pancreatic tumors.Forty-three patients suspected of having pancreatic tumors underwent contrast material-enhanced biphasic multi-detector row computed tomography (CT). Curved planar reformations were generated along the pancreatic duct, common bile duct, and major mesenteric vessels. Three blinded independent readers assessed the curved planar reformations and transverse images separately for the presence of tumor, resectability, and vascular involvement. The results were compared with those of a consensus panel who evaluated the curved planar reformations and transverse images together along with clinical data and surgical findings.Of 43 patients, 20 had pancreatic malignancies as judged by the consensus panel and proven at biopsy and/or clinical follow-up. For tumor detection, transverse images and curved planar reformations had an average sensitivity of 95.0% and 98.4% (P >.05), respectively, and an average specificity of 90.9% and 91.3% (P >.05), respectively. For tumor resectability, transverse images and curved planar reformations had an average sensitivity of 85.7% and 71.4% (P >.05), respectively, and an average specificity of 85.2% and 84.3% (P >.05), respectively. Average interpretation time was 6.4 minutes with transverse images and 4.1 minutes with curved planar reformations.Curved planar reformations are equivalent to transverse images in the detection of pancreatic tumors and determination of surgical resectability.

  View details for DOI 10.1148/radiol.2253010886

  View details for Web of Science ID 000179420800020

  View details for PubMedID 12461258

• A comprehensive approach to MR imaging of mesenteric ischemia ABDOMINAL IMAGING Chow, L. C., Chan, F. P., Li, K. C. 2002; 27 (5): 507-516

  View details for DOI 10.1007/s00261-001-0077-9

  View details for Web of Science ID 000177561500003

  View details for PubMedID 12172988

• Isoattenuating pancreatic adenocarcinoma at multi-detector row CT: Secondary signs RADIOLOGY Prokesch, R. W., Chow, L. C., Beaulieu, C. F., Bammer, R., Jeffrey, R. B. 2002; 224 (3): 764-768

  Abstract

  To assess the frequency of isoattenuating pancreatic adenocarcinoma with multi-detector row computed tomography (CT) and determine whether there are specific secondary signs that aid in detection.Fifty-three patients with pancreatic adenocarcinoma underwent contrast material-enhanced biphasic multi-detector row CT with curved planar reformation. Tumors were initially deemed isoattenuating or hypoattenuating to normal pancreatic parenchyma on the basis of visual inspection, and the degree of attenuation was confirmed by calculating the mean attenuation differences between normal pancreatic parenchyma and tumor (tumor-pancreas contrast) during the pancreatic phase. Indirect signs of pancreatic tumor were tabulated in patients with an isoattenuating tumor.Of the 53 patients, six (11%) had isoattenuating tumors with a mean tumor-pancreas contrast of 9.25 HU +/- 11.3 during the pancreatic phase and 4.15 HU +/- 8.5 during the portal venous phase. The secondary signs of pancreatic tumor in these six patients included an interrupted pancreatic duct (n = 5), dilated biliary and pancreatic ducts (n = 1), atrophic distal pancreatic parenchyma (n = 3), and mass effect and/or convex contour abnormality (n = 3). The mean tumor-pancreas contrast for the remaining 47 patients was 74.76 HU +/- 35.61 during the pancreatic phase.With no visible tumor-pancreas contrast for isoattenuating tumors, indirect signs such as mass effect, atrophic distal parenchyma, and an interrupted duct sign are important indicators for the presence of tumor.

  View details for DOI 10.1148/radiol.2243011284

  View details for Web of Science ID 000177621700021

  View details for PubMedID 12202711

• CT angiography of the arterial system RADIOLOGIC CLINICS OF NORTH AMERICA Chow, L. C., Rubin, G. D. 2002; 40 (4): 729-?

  Abstract

  CTA has become an important diagnostic tool in the evaluation of vascular diseases in virtually all parts of the body. Whereas CTA is able to provide images depicting exquisite anatomic detail, careful scanning technique and selection of scan parameters are critical for high quality studies. The choices to be made when prescribing a scan can seem daunting at first, but if one applies the principles outlined previously, CTA can be a relatively easy, fast, and safe diagnostic technique that is effective in the majority of patients with vascular disease.

  View details for Web of Science ID 000177204900005

  View details for PubMedID 12171182

• CT angiography of the subclavian artery: Utility of curved planar reformations JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Prokesch, R. W., Coulam, C. H., Chow, L. C., Bammer, R., Rubin, G. D. 2002; 26 (2): 199-201

  Abstract

  Despite advances in the diagnosis and treatment of peripheral vascular occlusive disease, an ever-aging population continues to provide scores of new cases requiring medical care. While traditional angiography has been the mainstay of diagnosis for many years, newer, less invasive techniques such as CT angiography with three-dimensional reformation are rapidly establishing themselves as first-line diagnostic modalities. We present a case of severe left subclavian artery stenosis that demonstrates the utility of curved planar reformation in providing a concise visual summary of the pertinent anatomy and abnormalities.

  View details for Web of Science ID 000174453500008

  View details for PubMedID 11884774

• 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

  Abstract

  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

• Miliary tuberculosis: radiographic features Applied Radiology Chow, L., Stark, P. 2000; 29: 25-28
• Intramural varices of the bile duct: An unusual pattern of cavernous transformation of the portal vein AMERICAN JOURNAL OF ROENTGENOLOGY Chow, L., Jeffrey, R. B. 1999; 173 (5): 1255-1256

  View details for Web of Science ID 000083312300021

  View details for PubMedID 10541099

• Blockade of angiotensin converting enzyme but not of angiotensin AT(1) receptors improves glucose tolerance EUROPEAN JOURNAL OF PHARMACOLOGY Chow, L., DeGasparo, M., Levens, N. 1997; 319 (1): 77–83

  Abstract

  This study compared the effect of benazepril, an angiotensin converting enzyme inhibitor to valsartan, an angiotensin AT1 receptor antagonist, on glucose tolerance in the conscious, spontaneously hypertensive rat. Intraperitoneal infusion of benazepril or valsartan at 1, 3 and 10 mg/kg per day produced equivalent dose-related reductions in systolic blood pressure for 12 weeks. Body weight gain during the treatment period was significantly reduced by infusion rates of benazepril. In contrast, only the highest infusion rate of valsartan significantly affected body weight gain. At the end of the 12-week treatment period, neither benazepril nor valsartan significantly affected glucose disposal during intravenous glucose tolerance tests. The insulin response to glucose challenge was unaffected by valsartan whereas following the highest infusion rate of benazepril the plasma levels were significantly reduced. The results demonstrate that benazepril but not valsartan reduces the insulin required to dispose of a glucose load.

  View details for DOI 10.1016/S0014-2999(96)00823-0

  View details for Web of Science ID A1997WE79500012

  View details for PubMedID 9030901

• Gastric acid secretion after blockade of angiotensin AT(1) receptors in the Na+-depleted rat EUROPEAN JOURNAL OF PHARMACOLOGY Chow, L., Zakrzewska, K., DeGasparo, M., Cumin, F., Levens, N. 1995; 294 (1): 309–17

  Abstract

  This study tested the hypothesis that angiotensin II acting through the angiotensin AT1 receptor plays an important role in the control of gastric acid secretion. Basal gastric acid secretion and gastric blood flow were lower in Na(+)-depleted animals, in which the renin-angiotensin system was activated, than in animals maintained on a normal Na+ diet. Intravenous infusion of pentagastrin at 0.6 microgram/kg/min increased gastric acid secretion to a greater extent in normal Na+ than in Na(+)-depleted animals. In addition to stimulating gastric acid secretion, pentagastrin increased gastric blood flow by proportionally the same amount in both normal and low Na+ animals. However, because basal gastric blood flow was considerably reduced in Na(+)-depleted animals, the increase produced by pentagastrin extended only to the levels observed in non-pentagastrin-treated normal Na+ animals. Lower gastric blood flow in response to pentagastrin may explain the smaller increase in gastric acid secretion observed in Na(+)-depleted animals. In Na(+)-depleted animals, the selective angiotensin AT1 receptor antagonist losartan did not affect basal gastric acid secretion or gastric blood flow, suggesting the involvement of mechanisms other than angiotensin II. Following blockade of angiotensin AT1 receptors, pentagastrin significantly increased gastric blood flow in Na(+)-depleted animals to levels observed with infusion of the pentapeptide in normal Na+ animals. The results suggested that the decrease in pentagastrin-stimulated acid secretion in Na(+)-depleted animals is mediated by angiotensin II acting through the angiotensin AT1 receptor, most probably through vascular mechanisms.

  View details for DOI 10.1016/0014-2999(95)00546-3

  View details for Web of Science ID A1995TN77700037

  View details for PubMedID 8788446

• PREOPERATIVE EXAMINATION OF LUNG-TRANSPLANT CANDIDATES - VALUE OF CHEST CT COMPARED WITH CHEST RADIOGRAPHY KAZEROONI, E. A., CHOW, L. C., WHYTE, R. I., MARTINEZ, F. J., LYNCH, J. P. AMER ROENTGEN RAY SOC. 1995: 1343–48

  Abstract

  The purpose of our study was to determine the usefulness of CT in examining candidates for lung transplantation to detect cancer not visible on plain chest radiographs (a finding that would exclude a patient from transplantation) and to determine which lung is more severely diseased to aid in the decision of which side to transplant.We reviewed the chest radiographs and CT scans of 190 transplant candidates during a 3-year period for findings suggestive of neoplasm, including lung nodules and atelectasis; we also reviewed the symmetry of disease. In the latter category, patients with primary pulmonary hypertension, Eisenmenger's complex (pulmonary vascular, not parenchymal, disease), and cystic fibrosis (for which bilateral transplantation is performed) were excluded. A total of 190 plain chest radiographs, 180 thin-section CT scans, and 31 standard CT scans were reviewed retrospectively.Plain chest radiographs revealed 20 noncalcified nodules; 13 were 8 mm or more in diameter, and 7 were less than 8 mm. CT scans revealed 66 noncalcified nodules; 37 were 8 mm or more in diameter, and 29 were less than 8 mm. Eight non-calcified nodules seen on plain chest radiographs were either absent on CT scans (and follow-up plain chest radiographs) or appeared calcified on CT scans. Solitary nodules in three patients proved to be bronchogenic carcinomas; two of these lesions were identified only on CT scans. CT prompted a change in the determination of which lung was more severely diseased from that made on the basis of plain radiography for 27 of 169 patients (16%) evaluated. Of the 45 patients who subsequently underwent transplantation, CT prompted a change in the determination of which side to transplant from that made on the basis of plain radiography for 4 patients (9%).CT provides additional information to supplement plain radiography in the examination of lung transplant candidates. This information can alter patient management, particularly when bronchogenic carcinoma is detected, and enable a better determination of which lung is more severely diseased to aid in the decision of which lung to transplant for single-lung transplantation.

  View details for DOI 10.2214/ajr.165.6.7484560

  View details for Web of Science ID A1995TF76800005

  View details for PubMedID 7484560

• IMPROVED GLUCOSE-METABOLISM FOLLOWING BLOCKADE OF ANGIOTENSIN-CONVERTING ENZYME BUT NOT ANGIOTENSIN AT(1) RECEPTORS EUROPEAN JOURNAL OF PHARMACOLOGY CHOW, L., DEGASPARO, M., LEVENS, N. 1995; 282 (1-3): 77–86

  Abstract

  This study compared the effect of benazepril, an angiotensin converting enzyme inhibitor ([S-(R*,R*)]-3-[[1-(ethoxycarbonyl)-3-phenylpropyl]amino]-2,3,4,5- tetrahydro-2-oxo) to valsartan, an angiotensin AT1 receptor antagonist ((S)-N-valeryl-N-[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]-methyl-valin e) on glucose metabolism and plasma lipid levels in 11- to 12-week-old conscious spontaneously hypertensive rats. Intraperitoneal infusion of benazepril or valsartan at 1, 3 and 10 mg/kg/day produced dose-related reductions in systolic blood pressure after 12 weeks which were not significantly different from each other. During the infusion, valsartan-treated animals gained weight at the same rate as controls, but all infusion rates of benazepril significantly suppressed normal weight gain, despite both compounds having similar antihypertensive effects. At the end of the 12-week treatment period, benazepril (3 and 10 mg/kg/day) significantly increased glucose disposal but did not significantly affect insulin disposal in insulin/glucose tolerance tests. In contrast, none of the infusion rates of valsartan significantly affected glucose or insulin disposal. Finally, compared to controls benazepril and valsartan were without effect on the fasting basal plasma concentrations of glucose, insulin, triglycerides, total cholesterol and K+. The results demonstrate that angiotensin converting enzyme inhibition and angiotensin AT1 receptor antagonism have similar antihypertensive effects, but express differences on body weight gain and insulin-stimulated glucose disposal in the conscious spontaneously hypertensive rat.

  View details for DOI 10.1016/0014-2999(95)00282-P

  View details for Web of Science ID A1995RT47700009

  View details for PubMedID 7498292