Faculty Bibliography

AIM: To retrospectively evaluate the prevalence of pelvic organ prolapse as an incidental finding on dynamic magnetic resonance imaging (MRI) using two different references lines. MATERIALS AND METHODS: Sixty women with symptoms unrelated to pelvic floor dysfunction who underwent MRI including a dynamic sagittal true fast imaging with steady-state free precession (TrueFISP) sequence during straining were identified. Two radiologists in consensus used the pubococcygeal line (PCL) and mid-pubic line (MPL) to diagnose and grade prolapse in all three pelvic compartments. RESULTS: Cystocele was absent, mild, moderate, and severe in 88% (53/60), 7% (4/60), 5% (3/60), and 0% (0/60) of patients, respectively, using PCL, versus 78% (47/60), 13% (8/60), 5% (3/60), and 3% (2/60) of patients, respectively, using MPL. Vaginal prolapse was absent, mild, moderate, and severe in 95% (57/60), 5% (3/60), 0% (0/60), and 0% (0/60) of patients, respectively, using PCL, versus 80% (48/60), 17% (10/60), 3% (2/60), and 0% (0/60) of patients, respectively, using MPL. Rectal descent was absent, mild, moderate, and severe in 63% (38/60), 10% (6/60), 23% (14/60), and 3% (2/60) of patients, respectively, using PCL, versus 43% (26/60), 27% (16/60), 27% (16/60), and 3% (2/60) of patients, respectively, using MPL. No enterocele, peritoneocele, or muscular defect was identified. Two percent (1/60) of patients had mild rectocele, 8% (5/60) had abnormal vesico-urethral angle, and 25% (15/60) had abnormal levator plate angle. CONCLUSION: In asymptomatic women, dynamic MRI identified the greatest degrees of prolapse in the posterior compartment. The MPL consistently yielded greater frequency of prolapse than the PCL. Findings of pelvic organ prolapse may be observed in asymptomatic patients and are of uncertain significance, requiring correlation with clinical and physical examination findings.

PURPOSE: A 2008 federal report expressed concern regarding substantial regional variation in imaging expenditures. The aims of this study were to evaluate trends in regional variation in Medicare imaging utilization and expenditures from 2007 to 2011 and to compare these trends with regional variation in other health service categories. METHODS: Data were based on CMS's Chronic Condition Data Warehouse and organized on the basis of 306 US health referral regions (HRRs). Imaging costs per beneficiary, standardized for regional differences in reimbursement rates, and imaging utilization per beneficiary were recorded per HRR from 2007 through 2011. Costs and utilization were also recorded for other service categories in 2011. Regional variation was assessed via relative risk (RR; the ratio between the highest and lowest HRRs) and coefficient of variation (CV; the standard deviation divided by the mean among all HRRs). Correlations between imaging and other service categories were assessed using Pearson's correlation coefficient. RESULTS: There was minimal change in regional variation in imaging costs or utilization between 2007 and 2011. Regional variation in imaging costs (RR, 5.70-5.88; CV, 33.0%-33.3%) was considerably greater than variation in imaging utilization (RR, 2.11%-2.25%; CV, 14.2%-14.6%). Imaging costs and utilization showed moderate to strong correlations with those of other service categories (r = 0.572-0.869). In 2011, regional variation in imaging utilization (RR, 2.25; CV, 14.2%) was considerably lower than variation in utilization of other service categories (RR, 2.80-10.78; CV, 20.9%-33.3%). CONCLUSIONS: Regional variation in imaging utilization is considerably lower than both variation in imaging costs and variation in utilization of other major service categories. It is unclear whether variation in imaging utilization provides an optimal individual target for major policy decisions.

OBJECTIVE. In this article, we describe 10 diagnostic challenges that may confound the interpretation of multiparametric prostate MRI for tumor, grouped into three categories on the basis of our experience: normal anatomic structures that may be misinterpreted as suspicious lesions if their normal appearance is not recognized, benign processes that may mimic tumor, and technical issues relating to acquisition and interpretation of diffusion-weighted imaging that may decrease sensitivity for tumor. Strategies for addressing these challenges are suggested. CONCLUSION. It is important that the radiologist involved in the interpretation of prostate MRI be aware of these pitfalls that will be encountered during routine clinical practice. This awareness can contribute to improved diagnostic performance in MRI interpretation.

OBJECTIVE. In this article, we provide our perspective on current multiinstitutional efforts to improve standardization of interpretation and reporting of multiparametric prostate MRI, emphasizing their strengths and limitations based on our experiences, and provide several suggestions for guiding continued initiatives for standardizing multiparametric prostate MRI reporting. CONCLUSION. Significant steps are being taken to facilitate the adoption of prostate MRI by urologists and other physicians in the community. Ultimately, however, prospective multicenter validation studies assessing the various aspects of a diagnostic test will be required.

OBJECTIVE. The purpose of this article is to evaluate the utility of various morphologic and quantitative MRI features in differentiating central renal cell carcinoma (RCC) from renal pelvic urothelial carcinoma. MATERIALS AND METHODS. Sixty patients (39 men and 21 women; mean [+/- SD] age, 65 +/- 14 years; 48 with central RCC and 12 with renal pelvic urothelial carcinoma) who underwent MRI, including diffusion-weighted imaging (b values, 0, 400, and 800 s/mm(2)) and dynamic contrast-enhanced imaging, before histopathologic confirmation were included. Tumor T2 signal intensity and apparent diffusion coefficients (ADCs) were measured and normalized to muscle and CSF (hereafter referred to as normalized T2 signal and normalized ADC, respectively) and then were compared using receiver operating characteristic analysis. Also, two blinded radiologists independently assessed all tumors for various qualitative features, which were compared with the Fisher exact test and unpaired Student t test. RESULTS. Urothelial carcinoma exhibited significantly lower normalized ADC than did RCC (p = 0.008), but no significant difference was seen in ADC or normalized T2 signal intensity (p = 0.247-0.773). Normalized ADC had the highest area under the curve (0.757); normalized ADC below an optimal threshold of 0.451 was associated with sensitivity of 83% and specificity of 71% for diagnosing urothelial carcinoma. Features that were significantly more prevalent in urothelial carcinoma included global impression of urothelial carcinoma, location centered within the collecting system, collecting system defect, extension to the ureteropelvic junction, preserved renal shape, absence of cystic or necrotic areas, absence of hemorrhage, homogeneous enhancement, and hypovascularity (all p < 0.033). Increased T1 signal intensity suggestive of hemorrhage was significantly more prevalent in RCC (p = 0.02). Interreader agreement for the subjective features ranged from 61.7% to 98.3%. CONCLUSION. In addition to various qualitative MRI parameters, normalized ADC has utility in differentiating central RCC from renal pelvic urothelial carcinoma. Such differentiation may assist decisions regarding possible biopsy and treatment planning.

AIM: To assess a novel method of three-dimensional (3D) co-registration of prostate cancer digital histology and in-vivo multiparametric magnetic resonance imaging (mpMRI) image sets for clinical usefulness. MATERIAL AND METHODS: A software platform was developed to achieve 3D co-registration. This software was prospectively applied to three patients who underwent radical prostatectomy. Data comprised in-vivo mpMRI [T2-weighted, dynamic contrast-enhanced weighted images (DCE); apparent diffusion coefficient (ADC)], ex-vivo T2-weighted imaging, 3D-rebuilt pathological specimen, and digital histology. Internal landmarks from zonal anatomy served as reference points for assessing co-registration accuracy and precision. RESULTS: Applying a method of deformable transformation based on 22 internal landmarks, a 1.6 mm accuracy was reached to align T2-weighted images and the 3D-rebuilt pathological specimen, an improvement over rigid transformation of 32% (p = 0.003). The 22 zonal anatomy landmarks were more accurately mapped using deformable transformation than rigid transformation (p = 0.0008). An automatic method based on mutual information, enabled automation of the process and to include perfusion and diffusion MRI images. Evaluation of co-registration accuracy using the volume overlap index (Dice index) met clinically relevant requirements, ranging from 0.81-0.96 for sequences tested. Ex-vivo images of the specimen did not significantly improve co-registration accuracy. CONCLUSION: This preliminary analysis suggests that deformable transformation based on zonal anatomy landmarks is accurate in the co-registration of mpMRI and histology. Including diffusion and perfusion sequences in the same 3D space as histology is essential further clinical information. The ability to localize cancer in 3D space may improve targeting for image-guided biopsy, focal therapy, and disease quantification in surveillance protocols.

OBJECTIVE. The purpose of this study was to assess associations between quantitative MRI metrics and pathologic indicators of aggressiveness of urothelial carcinoma of the bladder. MATERIALS AND METHODS. In this retrospective biinstitutional study, 37 patients (28 men and nine women; mean age, 73 +/- 12 years) who underwent pelvic MRI including diffusion-weighted imaging (b values 0, 400, and 800 s/mm(2)) and T2-weighted imaging before transurethral resection or cystectomy for urothelial carcinoma of the bladder were identified. Tumor diameter (measured on T2-weighted imaging), normalized T2 signal intensity (to muscle; hereafter labeled normalized T2) and apparent diffusion coefficient (ADC) were measured for all tumors. Mann-Whitney test and receiver operating characteristic analyses were used to identify associations between these metrics and histopathologic tumor stage and grade. RESULTS. Thirty-seven tumors were assessed (mean size, 35 +/- 23 mm; range 8-88 mm). At histopathologic analysis, 16 of 37 (43%) tumors were stage T2 or greater and 21 of 37 (57%) were stage T1 or lower, whereas 34 of 37 (92%) were high grade and three of 37 (8%) were low grade. High-stage (>/= T2) tumors showed greater tumor diameter, lower normalized T2, and lower ADC (p = 0.005-0.032) than low-stage (