Multiphasic Enhancement Patterns of Small Renal Masses (≤4 cm) on Preoperative Computed Tomography: Utility for Distinguishing Subtypes of Renal Cell Carcinoma, Angiomyolipoma, and Oncocytoma

• DOI: 10.1016/j.urology.2012.12.049
• Publication Date: 2013-04-18T05:45:37Z
• Authors: Phillip M. Pieror...; Elias S. Hyams; Salina Tsai; Zhaoyong Feng; Bruce J. Trock; Jeffrey K. Mullins; Pamela T. Johnson; Elliot K. Fishman; Mohamad E. Allaf
• Keywords: Adult; Male; Adolescent; Angiomyolipoma; Contrast Media; Middle Aged; Kidney Neoplasms; 3. Good health; Diagnosis, Differential; Young Adult; 03 medical and health sciences; Logistic Models; 0302 clinical medicine; Multidetector Computed Tomography; Adenoma, Oxyphilic; Humans; Female; Carcinoma, Renal Cell; Aged

To analyze the enhancement patterns of small renal masses (SRMs) during 4-phase computed tomography (CT) imaging to predict histology.One-hundred consecutive patients with SRMs and 4-phase preoperative CT imaging, who underwent extirpative surgery with a pathologic diagnosis of renal cell carcinoma (RCC), angiomyolipoma (AML), or oncocytoma, were identified from a single institution. An expert radiologist, blinded to histologic results, retrospectively recorded tumor size, RENAL (radius, exophytic/endophytic properties of the tumor, nearness of tumor deepest portion to the collecting system or sinus, anterior/posterior descriptor, and the location relative to polar lines) nephrometry score, tumor attenuation, and the renal cortex on all 4 acquisitions (precontrast, corticomedullary, nephrogenic, and delayed density).Pathologic diagnoses included 48 clear-cell RCCs (ccRCCs), 22 papillary RCCs, 10 chromophobe RCCs, 13 oncocytomas, and 7 AMLs. There was no significant difference in median tumor size (P = .8), nephrometry score (P = .98), or anatomic location (P >.2) among histologies. Significant differences were noted in peak enhancement (P <.001) and phase-specific enhancement (P <.007) by histology. Papillary RCCs demonstrated a distinct enhancement pattern, with a peak Hounsfield unit (HU) of 56, and greatest enhancement during the NG and delayed phases. The highest peak HU were demonstrated by ccRCC (117 HU) and oncocytoma (125 HU); ccRCC more often peaked in the corticomedullary phase, whereas oncocytoma peaked in the nephrogenic phase.In a series of patients with SRMs undergoing 4-phase CT, tumor histologies demonstrated distinct enhancement patterns. Thus, preoperative 4-phase CT imaging may provide useful information regarding pathologic diagnosis in patients undergoing extirpative surgery.