Prostate cancer detection: comparison of T2-weighted imaging, diffusion-weighted imaging, proton magnetic resonance spectroscopic imaging, and the three techniques combined.

BACKGROUND: Magnetic resonance (MR) imaging has been established as the best imaging modality for the detection, localization, and staging of prostate cancer on account of its high resolution of soft tissue and the possibilities of multiplanar and multiparameter scanning.

PURPOSE: To evaluate T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), MR spectroscopy (MRS), and the combination of these three MR techniques in the diagnosis of prostate cancer, as correlated to histopathologic findings.

MATERIAL AND METHODS: MR imaging, including T2WI, DWI, and MRS, was performed at 1.5T with a body coil combined with a spine coil in 42 cases. Diagnosis was confirmed by histopathology through systematic transrectal prostate biopsy. Apparent diffusion coefficient (ADC) maps were obtained with two b values (0 and 1000 s/mm(2)). The metabolic maps of 3D-MRS imaging were analyzed for the ratio of (Cho+Cre)/Cit in each sextant. All cases were evaluated by T2WI, DWI, and MRS, and then by the three methods combined. The statistical indicators and the receiver operating characteristic (ROC) curve analysis of each method were compared to the results of histopathology obtained by transrectal prostate biopsy.

RESULTS: 15 of 42 cases were confirmed to be cancerous, and 27 of 42 cases were noncancerous. All the 252 sextants were confirmed by biopsies, including 201 benign sextants and 51 malignant sextants. The sensitivity and the specificity for the detection of prostate cancer were 88.2% and 67.2% for T2WI, as the cutoff was 3; 82.4% and 81.6% for DWI, as the cutoff was 4; 84.3% and 98.0% for MRS, as the cutoff was 5; and 96.1% and 96.5% for the combined T2WI+DWI+MRS, as the cutoff was 4. In the ROC analysis, the correlative areas under the ROC curves (Az) were 0.848+/-0.030, 0.860+/-0.033, and 0.961+/-0.016 for T2WI, DWI, and MRS, respectively, and 0.978+/-0.009 for the combination of T2WI+DWI+MRS.

CONCLUSION: The accuracy of the detection of prostate cancer is increased through a combination of the three techniques. Moreover, MRS demonstrated higher accuracy compared with T2WI or DWI.