Comparison of T2* Mapping with Diffusion-Weighted Imaging in the Characterization of Low- vs Intermediate- and High-Grade Prostate Cancer.

Objective: To evaluate the diagnostic value of T-2* mapping compared with apparent diffusion coefficient (ADC) mapping in the characterization of low-grade (Gleason score, <= 6) vs intermediate-grade and high-grade (Gleason score >= 7) prostate cancer (PCa). Methods: 62 patients who underwent MRI before prostatectomy were evaluated. Two readers independently scored the probabilities of tumours in 12 regions of the prostate on T-2* and ADC images. The data were divided into two groups, i.e. low-vs intermediate-and high-grade PCa, and correlated with the histopathological results. The diagnostic performance parameters, areas under the receiver-operating characteristic curves and interreader agreements were calculated. Results: For Reader 2, ADC mapping exhibited a greater accuracy for intermediate-grade PCas than for high-grade PCas (0.77 vs 0.83, p < 0.05). For both readers, T-2* mapping exhibited a greater accuracy for intermediate-grade PCas than for high-grade PCas (Reader 1, 0.86 vs 0.81; Reader 2, 0.83 vs 0.78; p < 0.05). The areas under the curve of T-2* mappings were greater than those of the ADC mappings for the intermediate-and high-grade PCas (Reader 1, 0.83 vs 0.78; Reader 2, 0.80 vs 0.75; p < 0.05) but not for the low-grade PCas (Reader 1, 0.86 vs 0.84; Reader 2, 0.83 vs 0.82; p > 0.05). The weighted k value of T-2* mapping was 0.59. Conclusion: T-2* mapping improves the accuracy of the characterization of intermediate-and high-grade PCas but not low-grade PCas compared with ADC mapping. Advances in knowledge: T-2* mapping exhibited greater diagnostic accuracy than ADC mapping in the characterization of intermediate-and high-grade PCas. T-2* mapping exhibited limited value in the characterization of low-grade PCa.