Diagnostic evaluation of magnetization transfer and diffusion kurtosis imaging for prostate cancer detection in a re-biopsy population.

Abstract

Objective: To evaluate diffusion kurtosis imaging (DKI) and magnetization transfer imaging (MTI) compared to standard MRI for prostate cancer assessment in a re-biopsy population.

Methods: Thirty-patients underwent 3T-MRI including DKI (Kapp and Dapp) was acquired with b-values of 150/450/800/1150/1500 s/mm2 and MTI performed with and without MT saturation. Patients underwent transperineal biopsy on prospectively-defined MRI-targets. Receiver operating characteristic (ROC) analyses assessed the parameters and Wilcoxon-signed ranked test assessed relationships between metrics.

Results: 20 patients had ≥1 core positive for cancer in a total of 26 MRI-targets (Gleason 3+3 in 8, 3+4 in 12, ≥4+3 in 6); 13 peripheral (PZ) and 13 transition zone (TZ). Apparent diffusion-coefficient (ADC) and Dapp were significantly lower, and Kapp and MT ratio (MTR) significantly higher in tumour versus benign PZ/TZ (all p≤0.005); ROC values 0.767-1.000. Normal TZ had lower ADC and Dapp and higher Kapp and MTR compared to normal PZ. MTR showed moderate correlation to Kapp (r=0.570) and Dapp (r=-0.537) in normal tissue but a poor correlation in tumours. None of the measured parameters separated low-grade (Gleason 3+3) from higher-grade (≥3+4) disease for either PZ (p= 0.414-0.825) or TZ (p= 0.148-0.825).

Conclusion: ADC, Dapp, Kapp and MTR all distinguished benign tissue from tumour, but none reliably differentiated low from high-grade disease.