Faculty Bibliography

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: To assess the impact of the American Urological Association (AUA) guidelines advocating partial nephrectomy for T1 tumors guidelines on the likelihood of undergoing partial nephrectomy. MATERIALS AND METHODS: We analyzed the Nationwide Inpatient Sample (NIS), a dataset encompassing 20% of all United States inpatient hospitalizations, from 2007 through 2010. Our dependent variable was receipt of radical vs partial nephrectomy (55.50, 55.51, 55.52, and 55.54 vs 55.4) for a renal mass (International Classification of Disease, 9th Revision [ICD-9] code 189.0). The independent variable of interest was time of surgery (before or after the establishment of AUA guidelines); covariates included a diagnosis of chronic kidney disease (CKD), overall comorbidity, age, race, gender, geographic region, income, and hospital characteristics. Bivariate and multivariable adjusted logistic regression was used to determine the association between receipt of partial nephrectomy and time of guideline establishment. RESULTS: We identified 26,165 patients with renal tumors who underwent surgery. Before the guidelines, 4031 patients (27%) underwent partial nephrectomy compared to 3559 (32%) after. On multivariable analysis, undergoing surgery after the establishment of guidelines (odds ratio [OR] 1.20, 95% confidence interval [CI] 1.08-1.32, P <.01) was an independent predictor of partial nephrectomy. Other factors associated with partial nephrectomy were urban location, surgery at a teaching hospital, large hospital bed size, Northeast location, and Black race. Female gender and CKD were not associated with partial nephrectomy. CONCLUSION: Although adoption of partial nephrectomy increased after establishment of new guidelines on renal masses, partial nephrectomy remains an underutilized procedure. Future research must focus on barriers to adoption of partial nephrectomy and how to overcome them.