Diffusion-weighted MRI in the evaluation of renal lesions:preliminary results

摘要

The purpose of this study was to evaluate the capability and the reliability of diffusion-weighted MRIudin the evaluation of normal kidney and different renal lesions. 39 patients (10 normal volunteers and 29 patientsudwith known renal lesions) underwent MRI of the kidneys by using a 1.5 T superconducting magnet. Axial fatudsuppressed turbo spin echo (TSE) T2 and coronal fast field echo (FFE) T1 or TSE T1 weighted images wereudacquired for each patient. Diffusion-weighted (DW) images were obtained in the axial plane during breath-holdud(17 s) with a spin-echo echo planar imaging (SE EPI) single shot sequence (repetition time (TR)52883 ms, echoudtime (TE)561 ms, flip angle590°), with b value of 500 s mm22. 16 slices were produced with slice thickness ofud7 mm and interslice gap of 1 mm. An apparent diffusion coefficient (ADC) map was obtained at each sliceudposition. The ADC was measured in an approximately 1 cm region of interest (ROI) within the normal renaludparenchyma, the detected renal lesions and the collecting system if dilated. ADC values in normal renaludparenchyma ranged from 1.7261023 mm2 s21 to 2.6561023 mm2 s21, while ADC values in simple cystsud(n513) were higher (2.8761023 mm2 s21 to 4.0061023 mm2 s21). In hydronephrotic kidneys (n56) the ADCudvalues of renal pelvis ranged from 3.3961023 mm2 s21 to 4.0061023 mm2 s21. In cases of pyonephrosis (n53)udADC values of the renal pelvis were found to be lower than those of renal pelvis of hydronephrotic kidneysud(0.7761023 mm2 s21 to 1.0761023 mm2 s21). Solid benign and malignant renal tumours (n57) showed ADCudvalues ranging between 1.2861023 mm2 s21 and 1.8361023 mm2 s21. In conclusion diffusion-weighted MRudimaging of the kidney seems to be a reliable way to differentiate normal renal parenchyma and different renaluddiseases. Clinical experience with this method is still preliminary and further studies are required.