ADC mapping with 12 b values: an improved technique for image quality in diffusion prostate MRI

PurposeTo compare diffusion images and coefficients obtained with 4 b-value versus 12 b-value apparent diffusion coefficient (ADC) mapping for characterization of prostate lesions and how these coefficients relate and compare to the PI-RADS™ classification and Gleason grading system.MethodsPatients with indications for prostate cancer testing (n=158) underwent multiparametric 3T magnetic resonance imaging (MRI). Two diffusion sequences were acquired, one with 4 b values and one with 12 b values. ADC maps were calculated for each (ADC4 and ADC12) and the respective coefficients were tested for correlation with PI-RADS™ classification and Gleason score.ResultsThe ADC12 sequence produced images of superior quality and sharpness than ADC4. Normal-area means (ADC4, 1793.3×10−6mm2/s; ADC12, 1100×10−6mm2/s) were significantly lower than those of lesion areas (ADC4, 1105.9×10−6mm2/s; ADC12, 689.4×10−6mm2/s) (p<0.001). Both techniques behaved similarly and correlated well with PI-RADS™ classification, distinguishing scores 3, 4, and 5 and with means tending to decline with increasing Gleason grade. ADC12 mapping yielded higher specificity than ADC4 (82.6% vs. 72.3%).ConclusionsDiffusion with 12 values is a viable technique for examination of the prostate. It produced higher-quality images than current techniques and correlates well with PI-RADS™ classification and Gleason score.