Comparison of Apparent Diffusion Coefficient Calculation Between Two-Point and Multipoint b Value Analyses in Prostate Cancer and Benign Prostate Tissue at 3 T: Preliminary Experience

OBJECTIVE. The purpose of this study was to prospectively evaluate the reliability and variability of apparent diffusion coefficient (ADC) calculations between two-point and multipoint b value analyses in prostate cancer and benign prostate tissue. SUBJECTS AND METHODS. Forty-eight consecutive patients with suspected prostate cancer underwent diffusion-weighted MRI (DWI) at 3 T followed by surgery. DWI was examined under different b values. ADC maps were generated by two different methods: two-point b values (0 and 1000 s/mm(2)) and multipoint b values (0, 100, 300, 700, and 1000 s/mm(2)). Two independent readers measured ADC in the cancers, benign peripheral zone and transition zone, and obturator internus muscle. Statistical analyses were performed using the intraclass correlation coefficient (ICC), correlation of variation (CV), Bland-Altman test, and paired Student t test. RESULTS. The intermethod ADC calculation revealed excellent reliability for all tissues in both readers: cancer (ICC = 0.979-0.981), transition zone (0.989-0.993), peripheral zone (0.990-0.994), and obturator internus muscle (0.967-0.975). In both readers, the variability of the intermethod ADC calculation was 2.90-3.09% CV in cancer, 1.16-1.48% CV in the transition zone, 1.03-1.29% CV in the peripheral zone, and 2.44-2.62% CV in the obturator internus muscle. For interreader variability, the CVs of ADC calculation for two-point versus multipoint b value analyses in all tissues were 7.21-9.65% versus 7.18-9.01%. CONCLUSION. For estimating ADC values on 3-T DWI of the prostate, two-point b value analysis seems to present excellent correlation with multipoint b value analysis, with little error in accuracy.