Posterior tibial nerve stimulation: is ultrasound guided needle placement more accurate?

INTRODUCTION To compare the accuracy of the transcutaneous ultrasound (US) in detecting the tibial nerve (TN) as opposed to digital palpation in the performance of posterior tibial nerve stimulation (PTNS). MATERIALS AND METHODS: After Institutional Review Board (IRB) approval, 25 adults were enrolled to quantify the difference in position of the distal TN by the use of US as opposed to cutaneous palpation. The position of the TN was determined first by the palpation method and then by using a L12-4MHz high frequency Linear Array Transducer. The difference in position between the two methods was determined in both proximal-distal (PD [Knee-Sole]) and anterior-posterior planes (AP). Statistical analysis was completed with numeric variables summarized with the sample median, range, and interquartile range (IQR). Categorical variables were summarized with the number and percentage of patients. Comparisons between AP and PD distances were performed using a nonparametric Wilcoxon signed rank test. Box and whisker plots were used to display individual observations graphically. All analyses and graphics were performed using SAS statistical software (version 9.4M5, SAS Institute Inc., Cary, NC, USA). RESULTS: Twenty-five patients were studied. The median AP distance between US and digital palpation was 2 mm (range, 0-5 mm; IQR, 2-3 mm). The median PD distance between US and digital palpation was 4 mm (range, 0-9 mm; IQR, 3-5 mm). The median difference between the AP and PD distances was 2 mm (range, -3-7 mm; IQR, 0-4 mm, p < 0.001). CONCLUSION: The use of US identifies the nerve with statistically significant greater accuracy than palpation technique along the PD plane.

Utility of the Aortic-Lesion-Attenuation-Difference (ALAD) and Peak Early-Phase Enhancement Ratio (PEER) to differentiate benign from malignant renal masses.

INTRODUCTION: To evaluate the utility of the Aorta-Lesion-Attenuation-Difference (ALAD) and Peak Early-phase Enhancement Ratio (PEER) on contrast-enhanced computed tomography (CT) to differentiate between the appearances of chromophobe renal cell carcinoma, clear cell renal cell carcinoma, and oncocytoma. MATERIAL AND METHODS: ALAD and PEER values were retrospectively measured by a reviewer from 119 patients with surgically resected renal masses (chromophobe renal cell carcinoma n = 29, clear cell renal cell carcinoma n = 28, and oncocytoma n = 62). The ALAD value is expressed as: ALAD = Hounsfield Units aorta - Hounsfield Units mass. PEER is expressed as (Hounsfield Units contrast tumor - Hounsfield Units non-contrast tumor):( Hounsfield Units contrast cortex - Hounsfield Units non-contrast cortex). RESULTS: The ALAD median was 27.6 for oncocytomas, 68.5 for chromophobe renal cell carcinoma, and 55.4 for clear cell renal cell carcinoma. A significant difference between ALAD values of oncocytoma and chromophobe renal cell carcinoma was observed in the nephrographic (area under the ROC curve 0.92) and excretory phases (area under the ROC curve 0.95). The PEER median was 0.74 for oncocytomas and 0.37 for chromophobe renal cell carcinoma. The PEER values significantly differed while comparing oncocytomas and chromophobe renal cell carcinoma in the nephrographic and excretory phases. CONCLUSIONS: Preoperative contrast-enhanced CT ALAD and PEER values both significantly differentiate between chromophobe renal cell carcinoma and oncocytoma. PEER may be more effective in contrast-enhanced CT scans lacking distinct phases.