Using helical CT to evaluate renal cell carcinoma in patients undergoing hemodialysis: value of early enhanced images.

Abstract

The purpose of this study was to evaluate early and delayed enhanced helical CT for revealing renal cell carcinoma in patients undergoing hemodialysis. Over the course of 3 years, 630 chronic hemodialysis patients underwent early and delayed contrast-enhanced and unenhanced helical CT to detect renal cell carcinoma. Retrospective review showed that 23 of these patients later underwent either unilateral or bilateral nephrectomy. Two radiologists, unaware of the pathology results, independently reviewed these 23 examinations. The sensitivity and specificity of each early and delayed scan for revealing neoplasms were determined using pathology as the gold standard. The mean attenuation values of the neoplasms and parenchymas of end-stage kidneys on both early and delayed enhanced images were also compared. Helical CT revealed 225 lesions, 24 of which were found to be renal cell carcinomas at pathology. Delayed enhanced helical CT failed to detect one papillary carcinoma in an end-stage kidney with acquired cysts. Three nonpapillary carcinomas were not detected on delayed scans, and one was missed on an early scan of a patient without acquired cysts. The sensitivity and specificity of early enhanced CT for revealing renal cell carcinoma were 96% and 95%, respectively. In contrast, delayed enhanced CT achieved a sensitivity of 83% and a specificity of 94%. A significant difference in mean attenuation values between carcinomas and renal parenchymas was observed on the images with early enhancement but not on those with delayed enhancement (p < .0001). Early enhanced helical CT is superior to delayed enhanced helical CT for revealing renal cell carcinoma in end-stage kidneys.