Publications by authors named "Roozbeh Houshyar"

29 Publications

  • Page 1 of 1

A 61-year-old woman with jejunal lymphatic malformation visualized on computed tomography: a case report.

J Med Case Rep 2021 May 27;15(1):302. Epub 2021 May 27.

Department of Obstetrics and Gynecology, University of California Irvine, 333 City Boulevard West, Suite 1400, Orange, CA, 92868, USA.

Background: Jejunal lymphatic malformations are congenital lesions that are seldom diagnosed in adults and rarely seen on imaging.

Case Presentation: A 61-year-old Caucasian woman was initially diagnosed and treated for mucinous ovarian carcinoma. After an exploratory laparotomy with left salpingo-oophorectomy, a computed tomography scan of the abdomen and pelvis demonstrated suspicious fluid-containing lesions involving a segment of jejunum and adjacent mesentery. Resection of the lesion during subsequent debulking surgery revealed that the lesion seen on imaging was a jejunal lymphatic malformation and not a cancerous implant.

Conclusions: Abdominal lymphatic malformations are difficult to diagnose solely on imaging but should remain on the differential in adult cancer patients with persistent cystic abdominal lesions despite chemotherapy and must be differentiated from metastatic implants.
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http://dx.doi.org/10.1186/s13256-021-02872-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8157699PMC
May 2021

Prostate minimally invasive procedures: complications and normal vs. abnormal findings on multiparametric magnetic resonance imaging (mpMRI).

Abdom Radiol (NY) 2021 May 11. Epub 2021 May 11.

Department of Radiological Sciences, University of California, Irvine, Orange, CA, 92868-3201, USA.

Minimally invasive alternatives to traditional prostate surgery are increasingly utilized to treat benign prostatic hyperplasia and localized prostate cancer in select patients. Advantages of these treatments over prostatectomy include lower risk of complication, shorter length of hospital stay, and a more favorable safety profile. Multiparametric magnetic resonance imaging (mpMRI) has become a widely accepted imaging modality for evaluation of the prostate gland and provides both anatomical and functional information. As prostate mpMRI and minimally invasive prostate procedure volumes increase, it is important for radiologists to be familiar with normal post-procedure imaging findings and potential complications. This paper reviews the indications, procedural concepts, common post-procedure imaging findings, and potential complications of prostatic artery embolization, prostatic urethral lift, irreversible electroporation, photodynamic therapy, high-intensity focused ultrasound, focal cryotherapy, and focal laser ablation.
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http://dx.doi.org/10.1007/s00261-021-03097-6DOI Listing
May 2021

Segmentation of the Prostate Transition Zone and Peripheral Zone on MR Images with Deep Learning.

Radiol Imaging Cancer 2021 May;3(3):e200024

From the Department of Radiological Sciences, University of California, Irvine, 101 The City Drive South, Building 55, Suite 201, Orange, CA 92868 (M.B., R.H., K.T.H., C. Chahine, M.R.); Center for Artificial Intelligence in Diagnostic Medicine, University of California, Irvine, Irvine, Calif (C. Chantaduly, D.C., P.C.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (A.U.).

Purpose To develop a deep learning model to delineate the transition zone (TZ) and peripheral zone (PZ) of the prostate on MR images. Materials and Methods This retrospective study was composed of patients who underwent a multiparametric prostate MRI and an MRI/transrectal US fusion biopsy between January 2013 and May 2016. A board-certified abdominal radiologist manually segmented the prostate, TZ, and PZ on the entire data set. Included accessions were split into 60% training, 20% validation, and 20% test data sets for model development. Three convolutional neural networks with a U-Net architecture were trained for automatic recognition of the prostate organ, TZ, and PZ. Model performance for segmentation was assessed using Dice scores and Pearson correlation coefficients. Results A total of 242 patients were included (242 MR images; 6292 total images). Models for prostate organ segmentation, TZ segmentation, and PZ segmentation were trained and validated. Using the test data set, for prostate organ segmentation, the mean Dice score was 0.940 (interquartile range, 0.930-0.961), and the Pearson correlation coefficient for volume was 0.981 (95% CI: 0.966, 0.989). For TZ segmentation, the mean Dice score was 0.910 (interquartile range, 0.894-0.938), and the Pearson correlation coefficient for volume was 0.992 (95% CI: 0.985, 0.995). For PZ segmentation, the mean Dice score was 0.774 (interquartile range, 0.727-0.832), and the Pearson correlation coefficient for volume was 0.927 (95% CI: 0.870, 0.957). Conclusion Deep learning with an architecture composed of three U-Nets can accurately segment the prostate, TZ, and PZ. MRI, Genital/Reproductive, Prostate, Neural Networks © RSNA, 2021.
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http://dx.doi.org/10.1148/rycan.2021200024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8189171PMC
May 2021

Outcomes of Artificial Intelligence Volumetric Assessment of Kidneys and Renal Tumors for Preoperative Assessment of Nephron Sparing Interventions.

J Endourol 2021 Apr 13. Epub 2021 Apr 13.

University of California Irvine School of Medicine, 12219, Radiological Sciences, Orange, California, United States.

Background Renal cell carcinoma is the most common kidney cancer and the 13th most common cause of cancer death worldwide. Partial nephrectomy and percutaneous ablation, increasingly utilized to treat small renal masses and preserve renal parenchyma, require precise preoperative imaging interpretation. We sought to develop and evaluate a convolutional neural network (CNN), a type of deep learning artificial intelligence, to act as a surgical planning aid by determining renal tumor and kidney volumes via segmentation on single-phase computed tomography (CT). Materials and Methods After institutional review board approval, the CT images of 319 patients were retrospectively analyzed. Two distinct CNNs were developed for (1) bounding cube localization of the right and left hemi-abdomen and (2) segmentation of the renal parenchyma and tumor within each bounding cube. Training was performed on a randomly selected cohort of 269 patients. CNN performance was evaluated on a separate cohort of 50 patients using Sorensen-Dice coefficients (which measures the spatial overlap between the manually segmented and neural network derived segmentations) and Pearson correlation coefficients. Experiments were run on a GPU-optimized workstation with a single NVIDIA GeForce GTX Titan X (12GB, Maxwell architecture). Results Median Dice coefficients for kidney and tumor segmentation were 0.970 and 0.816, respectively; Pearson correlation coefficients between CNN-generated and human-annotated estimates for kidney and tumor volume were 0.998 and 0.993 (p < 0.001), respectively. End-to-end trained CNNs were able to perform renal parenchyma and tumor segmentation on a new test case in an average of 5.6 seconds. Conclusions Initial experience with automated deep learning artificial intelligence demonstrates that it is capable of rapidly and accurately segmenting kidneys and renal tumors on single-phase contrast-enhanced CT scans and calculating tumor and renal volumes.
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http://dx.doi.org/10.1089/end.2020.1125DOI Listing
April 2021

Comparison of Conventional and Triple Bolus Computerized Tomographic Urography Protocols for Radiation Dose Reduction in Hematuria Evaluation: A Randomized Controlled Trial.

J Urol 2021 Jun 19;205(6):1740-1747. Epub 2021 Feb 19.

Department of Urology, University of California, Irvine, Orange, California.

Purpose: Computerized tomographic urography is the diagnostic tool of choice for evaluating hematuria. In keeping with the ALARA (As Low As Reasonably Achievable) principle, we evaluated a triple bolus computerized tomography protocol designed to reduce radiation exposure.

Materials And Methods: Patients with macroscopic or microscopic hematuria were prospectively randomized to conventional computerized tomography (100) or triple bolus computerized tomography (100). The triple bolus computerized tomography protocol entails 2 scans: pre-contrast scan followed by 3 contrast injections at 40 seconds, 60 seconds and 20 minutes prior to the second scan to capture all 3 phases. The conventional computerized tomography protocol requires 4 scans: pre-contrast scan, and 3 post-contrast scans at the corticomedullary, nephrographic and excretory phases. Radiation exposure and the detection of urological pathology were recorded based on radiology reports.

Results: There were no differences in patient demographics or body mass index between the 2 groups. Triple bolus computerized tomography exposed patients to 33% less radiation (1,715 vs 1,145 mGy*cm for conventional vs triple bolus computerized tomography; p <0.001). For macroscopic hematuria, the pathology detection rates were 70% for triple bolus and 73% for conventional computerized tomography (p=0.72). For microscopic hematuria, the detection rates were 59% for triple bolus and 50% for conventional computerized tomography (p=0.68). In both groups, the rates of detection of urolithiasis, renal cysts, urological masses, bladder pathology and prostate pathology were no different between triple bolus and conventional computerized tomography.

Conclusions: In both the settings of macroscopic and microscopic hematuria evaluation, triple bolus computerized tomography significantly reduces radiation exposure while providing equivalent detection of genitourinary pathology compared to conventional computerized tomography. The ability to detect upper tract filling defects was not specifically tested.
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http://dx.doi.org/10.1097/JU.0000000000001603DOI Listing
June 2021

Medical management of appendicitis in early-term pregnancy.

BMJ Case Rep 2020 Aug 25;13(8). Epub 2020 Aug 25.

Obstetrics & Gynecology, University of California Irvine School of Medicine, Orange, California, USA

A 19-year-old G1 at 37 weeks presented with acute non-ruptured appendicitis. Her advanced gestational age and surgical anatomy presented a complex surgical scenario. She was treated with intravenous antibiotics and induction of labour, which resulted in resolution of the appendicitis and an uncomplicated vaginal delivery at early term. This case is an example that appendicitis occurring in early-term pregnancy can be successfully managed with intravenous antibiotics, but this is a complex clinical scenario with a limited evidence base to make management decisions. Future studies of medical management of appendicitis in pregnancy, specifically in later gestation, are needed to provide additional information to guide clinicians.
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http://dx.doi.org/10.1136/bcr-2020-234252DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449312PMC
August 2020

A 3D-2D Hybrid U-Net Convolutional Neural Network Approach to Prostate Organ Segmentation of Multiparametric MRI.

AJR Am J Roentgenol 2021 01 10;216(1):111-116. Epub 2020 Nov 10.

Department of Radiological Sciences, University of California, Irvine, CA.

Objective: Prostate cancer is the most commonly diagnosed cancer in men in the United States with more than 200,000 new cases in 2018. Multiparametric MRI (mpMRI) is increasingly used for prostate cancer evaluation. Prostate organ segmentation is an essential step of surgical planning for prostate fusion biopsies. Deep learning convolutional neural networks (CNNs) are the predominant method of machine learning for medical image recognition. In this study, we describe a deep learning approach, a subset of artificial intelligence, for automatic localization and segmentation of prostates from mpMRI.

Materials And Methods: This retrospective study included patients who underwent prostate MRI and ultrasound-MRI fusion transrectal biopsy between September 2014 and December 2016. Axial T2-weighted images were manually segmented by two abdominal radiologists, which served as ground truth. These manually segmented images were used for training on a customized hybrid 3D-2D U-Net CNN architecture in a fivefold cross-validation paradigm for neural network training and validation. The Dice score, a measure of overlap between manually segmented and automatically derived segmentations, and Pearson linear correlation coefficient of prostate volume were used for statistical evaluation.

Results: The CNN was trained on 299 MRI examinations (total number of MR images = 7774) of 287 patients. The customized hybrid 3D-2D U-Net had a mean Dice score of 0.898 (range, 0.890-0.908) and a Pearson correlation coefficient for prostate volume of 0.974.

Conclusion: A deep learning CNN can automatically segment the prostate organ from clinical MR images. Further studies should examine developing pattern recognition for lesion localization and quantification.
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http://dx.doi.org/10.2214/AJR.19.22168DOI Listing
January 2021

Effect of shelter-in-place on emergency department radiology volumes during the COVID-19 pandemic.

Emerg Radiol 2020 Dec 5;27(6):781-784. Epub 2020 Jun 5.

Department of Radiologic Sciences, Irvine School of Medicine, University of California, 101 The City Dr S, Orange, CA, 92868, USA.

Purpose: The coronavirus disease 2019 (COVID-19) pandemic has led to significant disruptions in the healthcare system including surges of infected patients exceeding local capacity, closures of primary care offices, and delays of non-emergent medical care. Government-initiated measures to decrease healthcare utilization (i.e., "flattening the curve") have included shelter-in-place mandates and social distancing, which have taken effect across most of the USA. We evaluate the immediate impact of the Public Health Messaging and shelter-in-place mandates on Emergency Department (ED) demand for radiology services.

Methods: We analyzed ED radiology volumes from the five University of California health systems during a 2-week time period following the shelter-in-place mandate and compared those volumes with March 2019 and early April 2019 volumes.

Results: ED radiology volumes declined from the 2019 baseline by 32 to 40% (p < 0.001) across the five health systems with a total decrease in volumes across all 5 systems by 35% (p < 0.001). Stratifying by subspecialty, the smallest declines were seen in non-trauma thoracic imaging, which decreased 18% (p value < 0.001), while all other non-trauma studies decreased by 48% (p < 0.001).

Conclusion: Total ED radiology demand may be a marker for public adherence to shelter-in-place mandates, though ED chest radiology demand may increase with an increase in COVID-19 cases.
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http://dx.doi.org/10.1007/s10140-020-01797-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7273127PMC
December 2020

Applications of Artificial Intelligence to Prostate Multiparametric MRI (mpMRI): Current and Emerging Trends.

Cancers (Basel) 2020 May 11;12(5). Epub 2020 May 11.

Department of Radiology, University of California, Irvine, Orange, CA 92868-3201, USA.

Prostate carcinoma is one of the most prevalent cancers worldwide. Multiparametric magnetic resonance imaging (mpMRI) is a non-invasive tool that can improve prostate lesion detection, classification, and volume quantification. Machine learning (ML), a branch of artificial intelligence, can rapidly and accurately analyze mpMRI images. ML could provide better standardization and consistency in identifying prostate lesions and enhance prostate carcinoma management. This review summarizes ML applications to prostate mpMRI and focuses on prostate organ segmentation, lesion detection and segmentation, and lesion characterization. A literature search was conducted to find studies that have applied ML methods to prostate mpMRI. To date, prostate organ segmentation and volume approximation have been well executed using various ML techniques. Prostate lesion detection and segmentation are much more challenging tasks for ML and were attempted in several studies. They largely remain unsolved problems due to data scarcity and the limitations of current ML algorithms. By contrast, prostate lesion characterization has been successfully completed in several studies because of better data availability. Overall, ML is well situated to become a tool that enhances radiologists' accuracy and speed.
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http://dx.doi.org/10.3390/cancers12051204DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281682PMC
May 2020

Variability of the Positive Predictive Value of PI-RADS for Prostate MRI across 26 Centers: Experience of the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel.

Radiology 2020 07 21;296(1):76-84. Epub 2020 Apr 21.

From the Departments of Radiology and Biomedical Imaging (A.C.W., R.J.Z.), Urology (A.C.W., P.R.C.), and Epidemiology and Biostatistics (C.E.M.) and the Clinical and Translational Science Institute (C.E.M.), University of California, San Francisco, 505 Parnassus Ave, M-392, Box 0628, San Francisco, CA 94143; Department of Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, Pa (J.M.A., R.B.P.); Departments of Radiology and Radiological Sciences (S.A., V.G.B) and Urologic Surgery (S.A.), Vanderbilt University Medical Center, Nashville, Tenn; Departments of Radiology (A.O.) and Urology (N.S.B), University of Chicago, Chicago, Ill; Departments of Radiology (J.O.B) and Nuclear Medicine (J.J.F.), Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands; Departments of Diagnostic Radiology (T.K.B., D.M.G), Interventional Radiology (S.E.M.), and Urology (J.F.W.), University of Texas MD Anderson Cancer Center, Houston, Tex; Diagnósticos da América S/A, Rio de Janeiro, Brazil (L.K.B); and Department of Radiology, Fluminense Federal University of Rio de Janeiro, Rio de Janeiro, Brazil (L.K.B.); Department of Radiology, University of California, San Diego, San Diego, Calif (M.T.B., M.E.H.); UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, Calif (P.R.C.); Department of Radiology, Northwestern University, Feinberg School of Medicine, Chicago, Ill (D.D.C., A.R.W.); Department of Radiology, University of British Columbia, Vancouver, Canada (S.D.C., R.D.); Department of Diagnostic Radiology, Oregon Health Science University, Portland, Ore (F.V.C., B.R.F.); Department of Radiology, University of New Mexico Health Sciences Center, Albuquerque, NM (S.C.E., B.S., J.B.S.); and Department of Radiology, Mayo Clinic, Rochester, Minn (A.T.F.). Joint Department of Medical Imaging, University Health Network-Mount Sinai Hospital-Women's College Hospital, Toronto, Canada (M.R.G., S.G.); Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wis (L.M.G.); Departments of Radiology (R.T.G.) and Surgery (R.T.G., T.J.P.), Duke University Medical Center and Duke Cancer Institute, Durham, NC; Department of Radiological Sciences and Urology, University of California, Irvine, Orange, Calif (R.H.); Virginia Commonwealth University School of Medicine, Richmond, Va (C.K.); Department of Radiology and Center for Imaging Sciences, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea (C.K.K.); Department of Radiology, University of Florida College of Medicine, Jacksonville, Fla (C.L.); Department of Radiology, Weill Cornell Medicine, New York, NY (D.J.A.M.); Department of Radiology, University of Colorado at Denver, Denver, Colo (N.U.P.); Molecular Imaging Program (B.T.) and Urologic Oncology Branch (P.A.P.), National Cancer Institute, National Institutes of Health, Bethesda, Md; Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center, Houston, Tex (V.S.T.); Departments of Radiology (A.B.R.) and Urologic Oncology (S.S.T.), New York University Langone Health, New York, NY; Department of Radiology, University of Cincinnati Medical Center, Cincinnati, Ohio (S.V.); Department of Urology, University of Minnesota Institute for Prostate and Urologic Cancers, Minneapolis, Minn (C.A.W.); and Department of Radiology, Virginia Commonwealth University, Richmond, Va (J.Y.).

Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate MRI across practices remains unknown. Purpose To estimate the positive predictive value (PPV) of PI-RADS for the detection of high-grade prostate cancer across imaging centers. Materials and Methods This retrospective cross-sectional study was compliant with the HIPAA. Twenty-six centers with members in the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel submitted data from men with suspected or biopsy-proven untreated prostate cancer. MRI scans were obtained between January 2015 and April 2018. This was followed with targeted biopsy. Only men with at least one MRI lesion assigned a PI-RADS score of 2-5 were included. Outcome was prostate cancer with Gleason score (GS) greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2). A mixed-model logistic regression with institution and individuals as random effects was used to estimate overall PPVs. The variability of observed PPV of PI-RADS across imaging centers was described by using the median and interquartile range. Results The authors evaluated 3449 men (mean age, 65 years ± 8 [standard deviation]) with 5082 lesions. Biopsy results showed 1698 cancers with GS greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2) in 2082 men. Across all centers, the estimated PPV was 35% (95% confidence interval [CI]: 27%, 43%) for a PI-RADS score greater than or equal to 3 and 49% (95% CI: 40%, 58%) for a PI-RADS score greater than or equal to 4. The interquartile ranges of PPV at these same PI-RADS score thresholds were 27%-44% and 27%-48%, respectively. Conclusion The positive predictive value of the Prostate Imaging and Reporting Data System was low and varied widely across centers. © RSNA, 2020 See also the editorial by Milot in this issue.
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http://dx.doi.org/10.1148/radiol.2020190646DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373346PMC
July 2020

PI-RADS Version 2 Is an Excellent Screening Tool for Clinically Significant Prostate Cancer as Designated by the Validated International Society of Urological Pathology Criteria: A Retrospective Analysis.

Curr Probl Diagn Radiol 2020 Nov - Dec;49(6):407-411. Epub 2019 Jun 29.

University of California, Irvine, Irvine, CA.

Objectives: To assess the utility of multiparametric MRI in detecting clinically significant prostate cancer (csPCa) by comparing PI-RADSv2 scores with International Society of Urological Pathology (ISUP) pathologic grading criteria.

Methods: Data from 137 patients were retrospectively analyzed. PI-RADSv2 scores were compared with pathologic grade using ISUP criteria. Pathologic grades were divided into clinically significant (groups 3-5) and clinically insignificant lesions (groups 1-2). Chi-squared analysis was performed for to assess correlation.

Results: Sensitivity and specificity of PI-RADSv2 score 3-5 lesions for detecting csPCa was 100% and 18.5%, respectively. Negative predictive value (NPV) is 100% for these lesions. When considering only PI-RADSv2 score 4-5 lesions, sensitivity decreases to 90% and specificity increases to 67.5%, with a NPV of 98.5%. When only PI-RADSv2 score 5 lesions are considered, sensitivity decreases to 50% and specificity increases to 90%, with a NPV of 95%.

Conclusions: Multiparametric MRI has excellent sensitivity for detecting csPCa. Specificity is poor for PI-RADSv2 score 3 lesions but improves significantly for PI-RADSv2 score 4 and 5 lesions. Overall, mpMRI is an excellent screening tool for csPCa, as designated by the recently validated ISUP criteria.

Advances In Knowledge: Multiple limitations of the longstanding Gleason pathologic scoring system have led to the development of new ISUP pathologic criteria, which is more focused on the clinical significance of lesions. There are currently insufficient studies evaluating and validating the ISUP criteria with PIRADS v2 evaluation of the prostate.
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http://dx.doi.org/10.1067/j.cpradiol.2019.06.010DOI Listing
June 2021

Multiple renal capillary hemangiomas in a patient with end-stage renal disease.

Radiol Case Rep 2019 Jun 3;14(6):750-754. Epub 2019 Apr 3.

Department of Radiological Sciences, University of California Irvine, Orange, CA, USA.

Renal capillary hemangiomas are rare and benign vascular tumors which are typically incidentally discovered on imaging. Surgical excision is often performed, as imaging appearance is similar to malignant lesions. Renal hemangiomas are typically solitary and unilateral. We present a rare case of multiple renal capillary hemangiomas in a patient with end-stage renal disease. Two hemangiomas were detected on imaging and 2 smaller hemangiomas were detected upon pathological evaluation, suggesting there may be a wider prevalence of smaller, radiographically-occult renal hemangiomas.
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http://dx.doi.org/10.1016/j.radcr.2019.03.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449744PMC
June 2019

Use of Neoadjuvant Sunitinib in Renal Cell Carcinoma of a Transplanted Kidney.

J Oncol Pract 2018 10 22;14(10):632-634. Epub 2018 Aug 22.

University of California Irvine, Irvine, CA.

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http://dx.doi.org/10.1200/JOP.18.00292DOI Listing
October 2018

Utility of quantitative apparent diffusion coefficient measurements and normalized apparent diffusion coefficient ratios in the diagnosis of clinically significant peripheral zone prostate cancer.

Br J Radiol 2018 Jul 21;91(1088):20180091. Epub 2018 Jun 21.

1 Radiological Sciences, University of California, Irvine Medical Center , Orange, CA , USA.

Objective: The aim of this study is to evaluate the utility of quantitative apparent diffusion coefficient (ADC) measurements and normalized ADC ratios in multiparametric MRI for the diagnosis of clinically significant peripheral zone (PZ) prostate cancer particularly among equivocally suspicious prostate lesions.

Methods: A retrospective analysis of 95 patients with PZ lesions by PI-RADSv2 criteria, and who underwent subsequent MRI-US fusion biopsy, was approved by an institutional review board. Two radiologists independently measured ADC values in regions of interest (ROIs) of PZ lesions and calculated normalized ADC ratio based on ROIs in the bladder lumen. Diagnostic performance was evaluated using ROC. Inter observer variability was assessed using intraclass correlation coefficient (ICC).

Results: Mean ADC and normalized ADC ratios for clinically significant and non-clinically significant lesions were 0.763 × 10-3 mm s, 29.8%; and 1.135 × 10-3 mm s, 47.2% (p < 0.001), respectively. Area under the ROC curve (AUC) was 0.880 [95% CI (0.816-0.944) and 0.885 (95% CI (0.814-0.955)] for ADC and ADC ratio, respectively. Optimal AUC threshold for ADC was 0.843 × 10-3 mm s (Sn 70.5%, Sp 88.2%) and for normalized ADC was 33.1% (Sn 75.0%, Sp 95.7%). intraclass correlation coefficient was high at 0.889.

Conclusion: Quantitative ADC measurement in PZ prostate lesions demonstrates excellent diagnostic performance in differentiating clinically significant from non-clinically significant prostate cancer with high inter observer correlation. Advances In knowledge: Quantitative ADC is presented as an additional method to evaluate lesions in mpMRI of the prostate. This technique may be incorporated in new and existing methods to improve detection and discrimination of clinically significant prostate cancer.
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http://dx.doi.org/10.1259/bjr.20180091DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209473PMC
July 2018

Validation of Prostate Imaging-Reporting and Data System Version 2: A Retrospective Analysis.

Curr Probl Diagn Radiol 2018 Nov 12;47(6):404-409. Epub 2017 Oct 12.

Department of Radiological Sciences, University of California, Irvine Medical Center, Orange, CA.

Purpose: Use of magnetic resonance imaging (MRI)/transrectal ultrasound fusion biopsies to determine the accuracy of multiparametric MRI (mpMRI), using Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2), for detecting clinically significant prostate cancer in the overall gland and specifically the peripheral zone (PZ) and transitional zone (TZ).

Methods: A retrospective analysis of patients who underwent fusion biopsy identified 137 men with 231 prostate lesions was approved by the Institutional Review Board. Subjects initially classified under PI-RADSv1 criteria were regraded using PI-RADSv2 by a radiologist blinded to PI-RADSv1 score and biopsy results. Spearman correlation, chi-squared, and logistic regression analysis were performed.

Results: There was positive correlation between PI-RADSv2 and Gleason scores (P < 0.001). In the PZ, mpMRI demonstrated 100% sensitivity, 100% negative predictive value, and 35.9% positive predictive value, compared to 100%, 100%, and 27.1%, respectively, for TZ lesions. When predicting clinically significant prostate cancer, the PI-RADSv2 area under the curve for TZ lesions was 0.844 (95% CI: 0.753-0.935, P < 0.001) and 0.769 (95% CI: 0.684-0.854, P < 0.001) for PZ lesions. Combining PI-RADSv2 with additional risk factors (body mass index, prostate-specific antigen density, digital rectal examination) improved the area under curve.

Conclusions: PI-RADSv2 achieves excellent sensitivity and negative predictive value for both PZ and TZ lesions.
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http://dx.doi.org/10.1067/j.cpradiol.2017.10.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6193550PMC
November 2018

Collision and composite tumors; radiologic and pathologic correlation.

Abdom Radiol (NY) 2017 12;42(12):2909-2926

Department of Radiological Sciences, Irvine School of Medicine, University of California, 101 The City Drive South, Suite #1105, Orange, CA, 92868, USA.

The terms composite and collision tumors have been used interchangeably throughout radiological literature. Both composite and collision tumors involve two morphologically and immunohistochemically distinct neoplasms coexisting within a single organ. However, collision tumors lack the histological cellular intermingling seen in composite tumors. Composite tumors often arise from a common driver mutation that induces a divergent histology from a common neoplastic source while collision tumors may arise from coincidental neoplastic change. The purpose of this review is to provide an overview of abdominal composite and collision tumors by discussing hallmark radiographic and pathological presentations of rare hepatic, renal, and adrenal case studies. A better understanding of the presentation of each lesion is imperative for proper recognition, diagnosis, and management of these unique tumor presentations.
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http://dx.doi.org/10.1007/s00261-017-1200-xDOI Listing
December 2017

Choledochoduodenal fistula in the setting of Crohn's disease.

Radiol Case Rep 2016 Dec 4;11(4):309-312. Epub 2016 Nov 4.

Department of Radiology, UC Irvine Medical Center, 101 The City Drive South, Orange, CA 92868, USA.

Of all the spontaneous fistulas that occur between the extrahepatic biliary system and the intestine, a choledochoduodenal fistula is rarely seen. When it does occur, it is most often secondary to a perforated duodenal ulcer, choledocholithiasis, or cholelithiasis. It may also be seen following complications related to iatrogenic injury or tuberculosis. Generally, choledochoduodenal fistulas are asymptomatic, but may present with vague abdominal pain, fever, and other symptoms related to cholangitis. As a result, they can be difficult to diagnose clinically before imaging is obtained. We present a case of a 74 year old, asymptomatic, female with a past medical history significant for Crohn's disease who was found to have a choledochoduodenal fistula demonstrated on MRCP, possibly secondary to her underlying inflammatory bowel disease.
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http://dx.doi.org/10.1016/j.radcr.2016.08.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5128396PMC
December 2016

Prostate cancer on computed tomography: A direct comparison with multi-parametric magnetic resonance imaging and tissue pathology.

Eur J Radiol 2016 Jan 24;85(1):261-267. Epub 2015 Oct 24.

Radiological Sciences, University of California, Irvine School of Medicine, 101 The City Drive South, Orange, CA 92868, United States.

Objectives: Multi-parametric prostate magnetic resonance imaging (MRI) is considered the current imaging standard for detection and staging of prostate cancer. The combination of anatomical and functional imaging provided in this exam significantly increases the accuracy of prostate cancer detection. Computed tomography (CT) imaging has so far been found to be lacking in this regard, however observations at our academic institution as well as evidence present in the literature support the proposition that CT could indeed be helpful in detecting prostate abnormalities that correspond to neoplasm. The purpose of this study was to prove that areas of focal mass-like enhancement on CT imaging directly correlate with prostate neoplasms as revealed on multi-parametric MRI and follow-up targeted biopsy.

Materials And Methods: This was a single institution retrospective study with 27 male subjects. Inclusion criteria required subjects to have a multi-parametric MRI of the prostate between January 1, 2014 and June 1, 2015 and a pelvic venous phase contrast-enhanced CT study between January 1, 2000 and June 1, 2015. Two blinded Radiologists read subjects' CT scans for any abnormalities of the prostate. CT and multi-parametric MRI results were compared and were considered concordant if focal or mass like enhancement to a greater degree than the background parenchyma was detected in the same areas of the prostate on CT scan as areas of decreased T2 signal, perfusion abnormalities, and restricted diffusion on multi-parametric MRI.

Results: CT results were directly compared to multi-parametric MRI findings and biopsy results. The overall agreement of MRI and CT is 85.19% (95% CI: 67.52-94.08%). The positive percent agreement is 78.95% (95% CI: 54.43-93.95%) and the negative percent agreement is 100.0% (95% CL: 63.06-100.0%). When CT results are directly compared to biopsy results, sensitivity and specificity of CT are 63.64% (95% CI: 30.79-89.07%) and 100.0% (95% CI: 47.82-100.0%). The positive predictive value (PPV) is 100.0% (95% CI: 59.04-100.0%) and the negative predictive value (NPV) is 55.56% (95% CI: 21.2-86.3%). When compared to MRI, CT has a lower sensitivity and a higher specificity, as well as a higher PPV and NPV. Logistic regression analysis did not show a significant relationship between concordance of MRI and CT and Gleason score, time between studies, age, and Prostate-specific antigen (PSA) level.

Conclusion: Incidental focal areas of mass-like enhancement in the peripheral prostate detected on venous phase contrast-enhanced CT imaging may indeed correlate with prostate neoplasm and it would be prudent to suggest further work-up with PSA and perhaps multi-parametric MRI, especially in high-risk patients.
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http://dx.doi.org/10.1016/j.ejrad.2015.10.013DOI Listing
January 2016

Renal Collision and Composite Tumors: Imaging and Pathophysiology.

Urology 2015 Dec 30;86(6):1159-64. Epub 2015 Sep 30.

Department of Radiology, Mayo Clinic, Scottsdale, AZ.

Objective: To illustrate the imaging appearances of a spectrum of renal collision and composite tumors. Occurrence of collision and composite tumors in the genitourinary tract is rare compared to the usual occurrence of synchronous tumors.

Methods: Case studies were chosen that represent the different tumors. Analysis was made on both the imaging and the pathology if excision was performed.

Results: Presence of 2 different cell types can lead to confusing imaging findings, and biopsy or excision is typically needed for final diagnosis. Some composite tumors have a characteristic appearance on imaging based on their pathologic features.

Conclusion: Familiarity with imaging findings may help radiologists include these tumors in their differential diagnosis.
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http://dx.doi.org/10.1016/j.urology.2015.07.032DOI Listing
December 2015

Assessing the clinical utility of color Doppler ultrasound for ovarian torsion in the setting of a negative contrast-enhanced CT scan of the abdomen and pelvis.

Abdom Imaging 2015 Oct;40(8):3206-13

Department of Radiological Sciences, University of California, Irvine, 101 The City Drive South, Orange, CA, 92697, USA.

Purpose: The purpose of this study is to evaluate the utility of color Doppler ultrasound (CDU) in the assessment of ovarian torsion following a negative contrast-enhanced computed tomography (CT) examination.

Methods: This is a retrospective study of women who presented to the ED with abdominal pain and received both a contrast-enhanced CT and CDU within a 24-h period. The abdominal/pelvic CT examinations were evaluated for findings specific to torsion, including ovarian size greater than 5 cm, the presence of free fluid, uterine deviation, fallopian tube thickening, ovarian fat stranding, smooth wall thickening, the presence of the "twisted pedicle" sign, and abnormal ovarian enhancement. The results were compared to the presence or absence of ovarian torsion on the concurrent US.

Results: The initial query yielded 834 cases among 789 women. Of those 834 cases, 283 cases in 261 women received both imaging modalities within a 24-h period. The CT examinations demonstrated 48 cases with an ovarian size greater than 5 cm. 84 cases showed the presence of free fluid. Three cases of fallopian tube thickening were identified. One case of smooth wall thickening and a "twisted pedicle" sign were noted. Fifteen cases demonstrated stranding of the peri-ovarian fat. Twenty nine cases showed abnormal ovarian enhancement. A total of 111 cases showed at least one positive finding. Fourteen positive cases were identified on the CDU studies. Of the 14 positive cases, 11 had ovarian size greater than 5 cm. Twelve cases demonstrated the presence of free fluid. There was no uterine deviation or smooth wall thickening. One twisted pedicle was noted. Seven cases showed peri-ovarian fat stranding. Ten cases showed abnormal enhancement. Abnormalities on CT were noted in all cases suspicious for ovarian torsion on CDU. No negative CT examinations were associated with a positive CDU. In this small sample size, the negative predictive value of a negative CT examination was 100%.

Conclusion: A negative contrast-enhanced CT examination of the abdomen and pelvis is sufficient to rule out ovarian torsion. Therefore, there is no utility in the addition of CDU specifically to evaluate for ovarian torsion following a negative contrast-enhanced CT scan of the abdomen and pelvis.
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http://dx.doi.org/10.1007/s00261-015-0535-4DOI Listing
October 2015

Duplex Doppler Imaging of Dialysis Fistulae and Grafts.

Curr Probl Diagn Radiol 2016 Nov - Dec;45(6):420-428. Epub 2015 Jun 9.

Department of Radiology, UC Irvine Medical Center, Orange, CA.

Arteriovenous fistulae and grafts for hemodialysis access are a lifeline in patients with end-stage renal disease. A significant cause of morbidity and mortality in this population is dialysis access dysfunction. Duplex ultrasound imaging is an excellent modality to evaluate arteriovenous fistulae and grafts, the 2 main types of long-term hemodialysis access. This review provides a detailed Doppler ultrasound protocol for evaluation of fistulae or grafts to familiarize imagers with their normal appearance, highlighting common dialysis access complications.
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http://dx.doi.org/10.1067/j.cpradiol.2015.06.003DOI Listing
May 2017

Altered Doppler flow patterns in cirrhosis patients: an overview.

Ultrasonography 2016 Jan 27;35(1):3-12. Epub 2015 May 27.

Department of Radiology, University of California Irvine, Orange, CA, USA.

Doppler ultrasonography of the hepatic vasculature is an integral part of evaluating precirrhotic and cirrhotic patients. While the reversal of the portal venous flow is a well-recognized phenomenon, other flow patterns, although not as easily understood, may play an important role in assessing the disease status. This article discusses the different characteristic flow patterns observed from the portal vein, hepatic artery, and hepatic vein in patients with liver cirrhosis or related complications and procedures. Knowledge of these different flow patterns provides additional information that may reinforce the diagnosis of cirrhosis, help in staging, and offer prognostic information for determining the direction of therapy. Doppler ultrasonography is invaluable when liver transplantation is being considered and aids in the diagnosis of cirrhosis and portal hypertension.
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http://dx.doi.org/10.14366/usg.15020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4701371PMC
January 2016

Massive hemorrhage from unsuspected pseudoaneurysm within an ulcer following "Roux-en-Y" gastric bypass.

Am J Gastroenterol 2015 Feb;110(2):354-5

Department of Radiology, University of California Irvine Medical Center, Orange, California, USA.

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http://dx.doi.org/10.1038/ajg.2014.389DOI Listing
February 2015

40-year-old female with menorrhagia and abdominal pain: A case of metastatic gestational trophoblastic neoplasia.

Radiol Case Rep 2015 3;10(1):1057. Epub 2015 Dec 3.

Choriocarcinoma is part of a rare spectrum of placental abnormalities known as gestational trophoblastic disease (GTD). It is the most invasive form of GTD, with a mortality rate approaching 100% if left untreated. It spreads predominantly hematogenously to multiple target sites, most commonly the lungs. Due to its hypervascular nature, it is often complicated by bleeding. We describe a case of choriocarcinoma in a 40-year-old female with metastases to the lungs, brain, and bilateral kidneys resulting in large retroperitoneal hematomas.
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http://dx.doi.org/10.2484/rcr.v10i1.1057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4921190PMC
July 2016

Composite liver tumors: a radiologic-pathologic correlation.

Clin Mol Hepatol 2014 Dec;20(4):406-10

University of California, Irvine, Orange, CA, USA.

Bi-phenotypic neoplasm refers to tumors derived from a common cancer stem cell with unique capability to differentiate histologically into two distinct tumor types. Bi-phenotypic hepatocellular carcinoma-cholangiocarcinoma (HCC-CC), although a rare tumor, is important for clinicians to recognize, since treatment options targeting both elements of the tumor are crucial. Imaging findings of bi-phenotypic HCC-CC are not specific and include features of both HCC and CC. A combination of imaging and immuno-histochemical analysis is usually needed to make the diagnosis.
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http://dx.doi.org/10.3350/cmh.2014.20.4.406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4278074PMC
December 2014

Chemotherapy induced liver abnormalities: an imaging perspective.

Clin Mol Hepatol 2014 Sep;20(3):317-26

Department of Radiological Sciences, University of California, Irvine, Orange, CA, USA.

Treating patients undergoing chemotherapy who display findings of liver toxicity, requires a solid understanding of these medications. It is important for any clinician to have an index of suspicion for liver toxicity and be able to recognize it, even on imaging. Cancer chemotherapy has evolved, and newer medications that target cell biology have a different pattern of liver toxicity and may differ from the more traditional cytotoxic agents. There are several hepatic conditions that can result and keen clinical as well as radiographic recognition are paramount. Conditions such as sinusoidal obstructive syndrome, steatosis, and pseudocirrhosis are more commonly associated with chemotherapy. These conditions can display clinical signs of acute hepatitis, liver cirrhosis, and even liver failure. It is important to anticipate and recognize these adverse reactions and thus appropriate clinical action can be taken. Often times, patients with these liver manifestations can be managed with supportive therapies, and liver toxicity may resolve after discontinuation of chemotherapy.
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http://dx.doi.org/10.3350/cmh.2014.20.3.317DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4197183PMC
September 2014

Emergent pediatric US: what every radiologist should know.

Radiographics 2012 May-Jun;32(3):651-65

Department of Radiology, Baystate Medical Center and Children's Hospital, Western Campus of Tufts University School of Medicine, 759 Chestnut St, Springfield, MA 01199, USA.

Appendicitis, intussusception, and hypertrophic pyloric stenosis (HPS) are three of the most common reasons for emergent abdominal imaging in pediatric patients. Although the use of computed tomography has risen dramatically over the past 2 decades, children are particularly at risk for the adverse effects of ionizing radiation, and even low-dose radiation is associated with a small but significant increase in lifetime risk of fatal cancer. In most emergency departments, the use of magnetic resonance (MR) imaging as a primary modality for the evaluation of a child with abdominal pain remains impractical due to its high cost, its limited availability, and the frequent need for sedation. Ultrasonography (US) does not involve ionizing radiation and, unlike MR imaging, is relatively inexpensive, is widely available, and does not require sedation. Another major advantage of US in abdominal imaging is that it allows dynamic assessment of bowel peristalsis and compressibility. Delayed diagnosis of any of the aforementioned disease processes can lead to serious morbidity and, in some cases, death. The ability to diagnose or exclude disease with US should be part of a core radiology skill set for any practice that includes a pediatric population.
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http://dx.doi.org/10.1148/rg.323115111DOI Listing
September 2012

A splice variant of the Drosophila vesicular monoamine transporter contains a conserved trafficking domain and functions in the storage of dopamine, serotonin, and octopamine.

J Neurobiol 2005 Sep;64(3):239-58

Department of Psychiatry and Biobehavioral Sciences, The David Geffen School of Medicine at UCLA, Gonda (Goldschmied) Center for Genetic and Neuroscience Research, 695 Charles Young Drive, Los Angeles, California 90095-1761, USA.

Vesicular monoamine transporters (VMATs) mediate the transport of dopamine (DA), serotonin (5HT), and other monoamines into secretory vesicles. The regulation of mammalian VMAT and the related vesicular acetylcholine transporter (VAChT) has been proposed to involve membrane trafficking, but the mechanisms remain unclear. To facilitate a genetic analysis of vesicular transporter function and regulation, we have cloned the Drosophila homolog of the vesicular monoamine transporter (dVMAT). We identify two mRNA splice variants (DVMAT-A and B) that differ at their C-terminus, the domain responsible for endocytosis of mammalian VMAT and VAChT. DVMAT-A contains trafficking motifs conserved in mammals but not C. elegans, and internalization assays indicate that the DVMAT-A C-terminus is involved in endocytosis. DVMAT-B contains a divergent C-terminal domain and is less efficiently internalized from the cell surface. Using in vitro transport assays, we show that DVMAT-A recognizes DA, 5HT, octopamine, tyramine, and histamine as substrates, and similar to mammalian VMAT homologs, is inhibited by the drug reserpine and the environmental toxins 2,2,4,5,6-pentachlorobiphenyl and heptachlor. We have developed a specific antiserum to DVMAT-A, and find that it localizes to dopaminergic and serotonergic neurons as well as octopaminergic, type II terminals at the neuromuscular junction. Surprisingly, DVMAT-A is co-expressed at type II terminals with the Drosophila vesicular glutamate transporter. Our data suggest that DVMAT-A functions as a vesicular transporter for DA, 5HT, and octopamine in vivo, and will provide a powerful invertebrate model for the study of transporter trafficking and regulation.
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http://dx.doi.org/10.1002/neu.20146DOI Listing
September 2005

Finding genetic contributions to sporadic disease: a recessive locus at 12q24 commonly contributes to patent ductus arteriosus.

Proc Natl Acad Sci U S A 2002 Nov 30;99(23):15054-9. Epub 2002 Oct 30.

Department of Medicine and Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA.

The causes of many sporadic diseases are unexplained; the contribution of recessive loci with reduced penetrance is one possibility that has been difficult to explore. We describe an approach to this problem by first searching for diseases with higher prevalence in populations with high rates of consanguinity, then determining whether disease cases are more commonly the product of consanguinous union than controls in such populations, followed by analysis of genetic linkage in consanguinous cases. We demonstrate the utility of this approach by investigation of congenital heart disease in Iran. We found that patent ductus arteriosus (PDA), a common congenital heart disease, accounts for a higher fraction of congenital heart disease in Iran (15%) than in the United States (2-7%). Moreover, Iranian PDA cases demonstrated a marked increase of parental consanguinity (63%), compared with the general Iranian population (25%) or control cases with tetralogy of Fallot (30%). The recurrence of PDA among siblings was 5%. A genomewide analysis of linkage in 21 unrelated consanguinous PDA cases demonstrated a multipoint logarithm of odds score of 6.27 in favor of linkage of PDA to a 3-centimorgan interval of chromosome 12q24, with 53% of kindreds linked. These findings together establish a recessive component to PDA and implicate a single locus, PDA1, in one third or more of all PDA cases in Iran; they further suggest a role for this locus in PDA worldwide. Finally, these results suggest a general approach to the identification of recessive contributions to sporadic diseases.
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http://dx.doi.org/10.1073/pnas.192582999DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC137543PMC
November 2002