Diagnostic accuracy of segmental enhancement inversion for the diagnosis of renal oncocytoma using biphasic computed tomography (CT) and multiphase contrast-enhanced magnetic resonance imaging (MRI)

Segmental enhancement inversion (SEI) is a controversial imaging finding reportedly specific for the diagnosis of renal oncocytoma. The purpose of this study was to re-evaluate SEI using biphasic CT and multiphase MRI. With research ethics board approval, a retrospective analysis of patients with resection or biopsy of oncocytoma or chromophobe renal cell carcinoma (Ch-RCC) between 2008-2012 was performed. Twenty-four patients with oncocytoma and 13 patients with Ch-RCC underwent CT, while 13 patients with oncocytoma and 10 patients with Ch-RCC underwent MRI. Two blinded radiologists reviewed the CT and MRI studies independently in separate sessions to assess for SEI. A third radiologist established consensus. Interobserver variability was calculated and diagnostic accuracy was compared using ROC and the Fisher exact test. There was no difference in detection of SEI between oncocytoma and Ch-RCC at CT [both readers (p = 0.65, 0.5) and consensus review (p = 0.29)] or MRI [both readers (p = 0.64, 0.74) and consensus review (p = 0.53)]. The interobserver variability at CT (K = 0.28-0.33) and MRI (K = 0.25-0.44) was fair. The sensitivity and specificity for diagnosis of oncocytoma were 21 % and 92 % at CT and 15 % and 90 % at MRI. SEI is not useful for the diagnosis of renal oncocytoma with CT or MRI. (orig.)