Diffusion-weighted MRI in the detection of prostate cancer: meta-analysis

The objective of our study was to estimate and compare the performance of diffusion-weighted imaging (DWI) with other MRI techniques including T2-weighted MRI for the detection of prostate cancer.

Searches of the PubMed and Scopus electronic databases for the terms "prostate," "cancer," "diffusion-weighted imaging," and "magnetic resonance imaging" using an end date of December 2010 were completed. All included studies had histopathologic correlation; 2×2 contingency data were constructed for each study. A Bayesian receiver operating characteristic (ROC) model was used across studies to determine sensitivity, specificity, and area under the full or partial ROC curve.

Nineteen articles consisting of a total of 5892 lesions were analyzed. Based on a 95% credible interval, DWI alone yielded a significantly better area under the ROC curve, sensitivity, and specificity (0.85, 0.69, 0.89, respectively) than T2-weighted imaging alone (0.75, 0.60, 0.76). Combined DWI and T2-weighted imaging (0.73, 0.70, 0.83) showed a similar area under the ROC curve but significantly better sensitivity and specificity than T2-weighted imaging alone. DWI and combined DWI and T2-weighted imaging yielded similar overall sensitivity, but DWI alone showed better overall specificity than combined DWI and T2-weighted imaging. At specificities of greater than 80%, combined DWI and T2-weighted imaging yielded a partial area under the ROC curve (0.138) similar to that of DWI alone (0.129) and was significantly better than the partial area under the ROC curve of T2-weighted imaging alone (0.070). DWI alone and combined DWI and T2-weighted imaging appear to be superior to dynamic contrast-enhanced imaging alone (area under the ROC curve, 0.79; sensitivity, 0.58; specificity, 0.82).

DWI appears to improve diagnostic performance and can be a useful adjunct to conventional anatomic imaging for identifying tumor foci in prostate cancer.