Role of diffusion-weighted magnetic resonance imaging in prostate cancer evaluation.

ABSTRACT

PURPOSE: The authors analysed the role of diffusion-weighted imaging (DWI) as an additional tool in magnetic resonance (MR) evaluation of prostate cancer. MATERIALS AND METHODS: Forty-one patients with suspected prostate cancer underwent MR imaging (1.5 Tesla). A DWI sequence was added to the standard morphological protocol, with a maximum b value of 1,000 s/mm(2). Diffusion maps were obtained, and the apparent diffusion coefficient (ADC) was calculated by drawing a region of interest (ROI) over healthy tissue and areas suspicious for malignancy. Histology was considered the gold standard. RESULTS: The areas correctly classified by MR imaging (42/51) had a low signal intensity on T2-weighted imaging and low ADC value (0.99 ± 0.15 mm(2)/s; p<0.01) compared with the healthy peripheral zone (PZ) (1.73 ± 0.27 mm(2)/s; p<0.01). Nine areas classified as suspicious for malignancy on T2-weighted sequences showed high ADC (1.44 ± 0.06 mm(2)/s; p<0.01) and were confirmed to be disease free by subsequent histological examination. The accuracy of morphofunctional MR imaging was 81.6% compared with 73.7% of the morphological analysis alone. CONCLUSIONS: The addition of DWI to the standard protocol increases the overall diagnostic performance of MR imaging in detecting prostatic cancer. Thus, DWI can help the clinician determine the most appropriate management strategy for the patient.