Diagnosis and Grading of Prostate Cancer by Relaxation Maps From Synthetic MRI

BACKGROUND: The interpretation system for prostate MRI is largely based on qualitative image contrast of different tissue types. Therefore, a fast, standardized, and robust quantitative technique is necessary. Synthetic MRI is capable of quantifying multiple relaxation parameters, which might have potential applications in prostate cancer (PCa). PURPOSE: To investigate the use of quantitative relaxation maps derived from synthetic MRI for the diagnosis and grading of PCa. STUDY TYPE: Prospective. SUBJECTS: In all, 94 men with pathologically confirmed PCa or benign pathological changes. FIELD STRENGTH/SEQUENCE: T1 -weighted imaging, T2 -weighted imaging, diffusion-weighted imaging, and synthetic MRI at 3.0T. ASSESSMENT: Four kinds of tissue types were identified on pathology, including PCa, stromal hyperplasia (SH), glandular hyperplasia (GH), and noncancerous peripheral zone (PZ). PCa foci were grouped as low-grade (LG, Gleason score /=7). Regions of interest were manually drawn by two radiologists in consensus on parametric maps according to the pathological results. STATISTICAL TESTS: Independent sample t-test, Mann-Whitney U-test, and receiver operating characteristic curve analysis. RESULTS: T1 and T2 values of PCa were significantly lower than SH (P = 0.015 and 0.002). The differences of T1 and T2 values between PCa and noncancerous PZ were also significant (P /= 0.535). DATA CONCLUSION: Relaxation maps derived from synthetic MRI were helpful for discriminating PCa from other benign pathologies. But the overall diagnostic performance was inferior to the ADC values. T2 , PD, and ADC values performed similarly in discriminating LG from HG PCa lesions. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2.