Diffusion-Weighted MR Imaging in the Evaluation of Renal Tumours

The aim of this study was to evaluate the capability and the reliability of diffusion-weighted MR imaging to differentiate benign from malignant renal lesions. Twenty healthy volunteers and 48 patients with known renal lesions underwent MR of the kidneys by using a 1.5 T superconductive magnet. Diffusion-weighted images (DWI) were obtained on the axial plane during breath-hold (17 s) with a SE EPI single shot sequence using a b value of 500 s/mm². One region of interest (ROI) (lesions<than 3 cm) or 3 ROI (lesions > than 3 cm) were placed within the lesion for the measurement of apparent diffusion coefficient (ADC). ADC map was obtained at each slice position. Mean ADC value in normal renal parenchyma was 2.2± 0.20 × 10^-3 mm²/s, while ADC values in simple cysts (n=20) were higher (mean ADC values 3.65±0.09 × 10^-3 mm²/S). Solid benign and malignant renal tumors (n=19) showed a mean ADC value of 1.7±0.48 × 10^-3 mm²/sec. The comparison between ADC values in normal parenchyma group and tumour group were found to be statistically significant (p