Characteristic finding of renal oncocytoma and clear-cell renal cell carcinoma with multiphase CT

Abstract

Objective To evaluate characteristic imaging findings of tumor attenuation in 4-phase CT between renal oncocytoma ( RO ) and clear-cell renal ceil carcinoma ( ccRCC ) of small tumor size (≤Scm).Methods Fifty-six patients with histologically confirmed renal masses (11 ROs and 45 ccRCCs) were included in this study.Heterogeneous enhancement was found all tumors during the corticomedullary phase (CMP).The CT values of the normal renal cortex,the relatively high enhanced region and the relatively less-enhanced region of the tumor were measured in each phase.Statistical comparison was carried out by Chi-square test or Mann-Whitney test.Results In CMP,the CT value of the relatively high enhanced region in RO [ 163.0 HU ( 141.0—178.0 HU) ] was significantly lower than that in ccRCC [ 194.0 HU ( 166.5—235.0 HU) ; Z = -2.847,P =0.004].Compared CMP with the excretory phase,the attenuation of the relatively highly enhanced region in RO [70.0 HU (41.0—86.0 HU)] were significantly lower than that in ccRCC [87.0 HU (65.0—126.5 HU) ] (Z= -2.032,P =0.042).In the excretory phase,9 of 11 ROs had a further enhancement with its relatively less-enhanced region which was significantly higher than that in ccRCC (21/45 ; x2 = 4.391,P = 0.036).Conclusions In CMP,the CT value of the relatively high enhanced region in RO was significantly lower than that in ccRCC.Compared with ccRCC,in the excretory phase,the RO had less attenuation of the relatively highly enhanced region with homogeneous density. Key words: Kidney neoplasm; Tomography; X-ray computed; Comparative study