Renal masses: characterization with Doppler US.

The vascularity of indeterminate renal masses in 70 patients was investigated prospectively with duplex ultrasound. The peak-systolic Doppler shift frequency obtained from the renal mass was utilized to attempt distinction between benign and malignant lesions. With use of the criterion of a peak-systolic Doppler shift frequency of 2.5 kHz or greater as evidence of neovascularity, 26 of 37 malignant lesions demonstrated tumor signals (70% sensitivity). Thirty-one of 33 benign lesions lacked tumor signals (94% specificity). Both of the false-positive lesions were infections with inflammatory masses, with peak frequencies of 3.0 and 3.7 kHz. Tumor vascularity in most malignant renal mass lesions gives rise to abnormal, high-frequency, Doppler-shifted signals that can aid the differential diagnosis of renal masses.