Prostate cancer detection with MRI: is dynamic contrast-enhanced imaging necessary in addition to diffusion-weighted imaging?

PURPOSE To assess the feasibility of using magnetic resonance imaging for prostate cancer detection without using a contrast material. MATERIALS AND METHODS T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCEI) were performed using a phased-array coil at 1.5 T. These examinations were performed in 178 patients with elevated serum prostate-specific antigen levels (>4.0 ng/mL) before systematic needle biopsy. Two radiologists independently evaluated images from DWI, DCEI, and a combination of the two techniques by referring to a T2WI image and by using a predefined confidence scale for cancer detection. The right and left halves of the peripheral zone and the central gland were separately rated. The diagnostic performance (A(z)) of each technique was assessed by analyzing their associated area under the receiver operating characteristic curves. The results of a biopsy served as a reference standard. RESULTS Prostate cancer was detected in 72 (40.4%) of the 178 patients. For the entire prostate, the diagnostic performances of DWI (A(z) = 0.848) (P < 0.001) and the combined technique (A(z) = 0.845) (P < 0.001) were significantly more accurate than that of DCEI (A(z) = 0.746). DWI (74.8%) (P < 0.001) and the combined technique (72.9%) (P < 0.001) were significantly more sensitive than DCEI (52.8%). The numbers of cancer lesions that were interpreted using only DWI or DCEI were 83 (26.1%) and 13(4.1%) of the 318 study lesions, respectively. CONCLUSION DWI and the combined technique are more accurate and sensitive than DCEI in the detection of prostate cancer; however, DWI and DCEI play complementary roles in the accurate detection of prostate cancer.