Faculty Bibliography

OBJECTIVES: To evaluate changes in single-kidney glomerular filtration rate (SK-GFR) using low-dose dynamic contrast-enhanced magnetic resonance (MR) renography (MRR) in patients undergoing partial nephrectomy for renal masses. MATERIALS AND METHODS: In this Health Information Patient Protection Act-compliant prospective study, 18 patients with renal masses underwent preoperative MR imaging at 1.5 T for renal mass evaluation and low-dose gadolinium-enhanced MRR. Magnetic resonance renography was repeated approximately 48 to 72 hours and 6 months after partial nephrectomy. Single-kidney glomerular filtration rate was calculated from the MRR images, and the right and left kidney values were summed for total MR-GFR. Postoperative changes in SK-GFR and MR-GFR were compared with changes in estimated glomerular filtration rate calculated using modification of diet in renal disease formula, renal lesion characteristics, ischemia type (warm vs cold), and ischemia time. RESULTS: A decrease in the operated kidney SK-GFR was seen in 15 of the 18 patients, with a mean (SD) loss of 31% (23%), whereas estimated glomerular filtration rate decreased in 13 of the 18 patients with mean (SD) decrease of 19% (14%). Decrease in SK-GFR was greatest in the patients with warm ischemia time greater than 40 minutes and least in the patients with cold ischemia. In the immediate postoperative period, 6 of 7 patients (86%) with preoperative MR-GFR less than 60 mL/min per 1.73 m failed to demonstrate compensatory increase in SK-GFR in the nonoperated kidney, whereas 5 of 11 patients with baseline MR-GFR more than 60 mL/min per 1.73 m showed compensatory increase in nonoperated kidney SK-GFR. CONCLUSIONS: Magnetic resonance renography can demonstrate functional loss in the operated kidney and compensatory increase in the function of the contralateral kidney, thus enabling evaluation of various surgical techniques on kidney function.

Background: Small renal masses (SRM) are comprised of a heterogeneous group of tumors with some having malignant potential. Although surgery is the standard treatment for SRMs, emerging data suggests that surgery in the elderly or morbidly ill patients may be unnecessary and may adversely impact non-oncologic outcomes. We analyzed a population-based cohort of patients to identify predictors of surveillance and assess the impact of surveillance on overall survival, kidney cancer-specific survival and cardiovascular (CV) events, compared with surgery. Methods: From surveillance, epidemiology, and end results (SEER) cancer registry data linked with Medicare claims, we performed a retrospective cohort study of patients 66 years of age or older who received surgery or surveillance for SRM (< 4 cm) diagnosed between 2000 to 2007. Propensity score methods were used to control for potential confounders in multivariable analysis. Results: Of 8,317 patients, 5,706 (70%) underwent surgery and 2,611 (31%) underwent surveillance. The use of surveillance increased from 25% in 2000 to 37% in 2007 (p < 0.001). During a median follow-up of 58 months, 2,053 (25%) patients had at least one CV event and 2,078 (25%) patients died, including 277 (3%) who died of kidney cancer. Compared with surgery, surveillance was associated with a significantly lower risk of death from any cause (hazard ratio [HR], 0.84; CI, 0.75-0.94) and of suffering a CV event (HR, 0.79; CI 0.70-0.89), controlling for patient and disease characteristics. Kidney cancer-specific survival did not differ by treatment approach (HR, 0.89; CI, 0.66-1.21). Conclusions: There is increasing utilization of surveillance as an initial treatment strategy for patients with SRMs. For older patients with SRM, surveillance does not appear to adversely affect kidney cancer-specific survival, while surgery may be associated with CV complications and an increased risk of death from any cause. Surveillance should be considered an option for patients with SRM who ar!

Ectopic ureters are rare congenital mesonephric duct malformations with a higher prevalence in women than men. In women, ectopic ureters are often associated with a duplicated collecting system, whereas in men, ectopic ureters usually drain a single system and are associated with renal dysplasia and obstruction. Presentation and diagnosis generally occurs in the pediatric age group. Herein, we present an unusual case of delayed diagnosis of ectopic insertion of the upper pole ureter in a completely duplicated left kidney causing massive hydroureteronephrosis in an adult man.

OBJECTIVE. The purpose of this review is to describe the role of functional renal MRI, or MR renography, in the care of patients with renal masses undergoing partial nephrectomy. CONCLUSION. MR renography can be used to monitor renal functional outcome for patients undergoing partial nephrectomy and may help guide patient selection in this population with elevated risk of chronic kidney disease.

PURPOSE: To assess dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) tracer pharmacokinetic parameters obtained with Generalized Kinetic Model (GKM) and extended Shutter Speed Model (SSM2) in renal tumors stratified by histologic subtypes. MATERIALS AND METHODS: In all, 24 patients with renal tumors were imaged at 1.5 T utilizing DCE-MRI with high temporal resolution (1.2 sec/temporal frame) prior to surgery. Tracer kinetic analysis was performed for the entire tumor using individualized aortic input function. GKM and SSM2 were employed to generate transfer constant (K(trans) ), plasma volume, and interstitial volume. These parameters, and DeltaK(trans) (K(trans) SSM2 - K(trans) GKM) were compared between tumors stratified by histologic subtype. RESULTS: There were 25 renal tumors: 15 clear cell, 4 papillary, 3 chromophobe, and 3 oncocytoma/oncocytic subtype. K(trans) GKM was significantly higher in chromophobe compared to other subtypes (P < 0.01). Using K(trans) GKM > 1.0 min(-1) , chromophobe were diagnosed with 100% sensitivity and 90.9% specificity. K(trans) SSM2 was higher than K(trans) GKM for all renal tumors except for all chromophobe and two clear cell subtype. Using K(trans) GKM > 1.0 min(-1) and Delta K(trans) < 0, chromophobe could be discriminated from other lesions with 100% accuracy. CONCLUSION: K(trans) obtained with GKM and SSM2 analysis can potentially discriminate chromophobe from other renal lesions with high accuracy. J. Magn. Reson. Imaging 2013;. (c) 2013 Wiley Periodicals, Inc.