Characterisation of renal masses with colour flow Doppler ultrasonography.

Colour flow Doppler ultrasonography (US) was used in 24 renal masses (12 benign, 12 malignant) to investigate the vascularity of the lesion and thus to characterise the mass. A colour flow Doppler US device (Toshiba 270 A) with a convex probe of 3.75 MHz was used. Colour flow and the peak-systolic Doppler shift frequency obtained from the renal mass were used to distinguish between benign and malignant lesions. Ten of 12 malignant lesions demonstrated colour flow together with Doppler signals greater than 2.5 kHz (mean 3.5 kHz). None of the 12 benign renal masses demonstrated colour flow or tumour signals. The majority of malignant lesions give rise to neovascularisation and so high frequency Doppler-shifted signals. Thus colour flow Doppler sonography is the most reliable means of differentiating benign from malignant renal masses.