Value of T₂ Mapping MRI for Prostate Cancer Detection and Classification

Currently, multi-parametric prostate MRI (mpMRI) consists of a qualitative T₂ , diffusion weighted, and dynamic contrast enhanced imaging. Quantification of T₂ imaging might further standardize PCa detection and support artificial intelligence solutions.

To evaluate the value of T₂ mapping to detect prostate cancer (PCa) and to differentiate PCa aggressiveness.

Retrospective single center cohort study.

Forty-four consecutive patients (mean age 67 years; median PSA 7.9 ng/mL) with mpMRI and verified PCa by subsequent targeted plus systematic MR/ultrasound (US)-fusion biopsy from February 2019 to December 2019.

Standardized mpMRI at 3 T with an additionally acquired T₂ mapping sequence.

Primary endpoint was the analysis of quantitative T₂ values and contrast differences/ratios (CD/CR) between PCa and benign tissue. Secondary objectives were the correlation between T₂ values, ISUP grade, apparent diffusion coefficient (ADC) value, and PI-RADS, and the evaluation of thresholds for differentiating PCa and clinically significant PCa (csPCa).

Mann-Whitney test, Spearman's rank (r_s ) correlation, receiver operating curves, Youden's index (J), and AUC were performed. Statistical significance was defined as P < 0.05.

Median quantitative T₂ values were significantly lower for PCa in PZ (85 msec) and PCa in TZ (75 msec) compared to benign PZ (141 msec) or TZ (97 msec) (P < 0.001). CD/CR between PCa and benign PZ (51.2/1.77), respectively TZ (19.8/1.29), differed significantly (P < 0.001). The best T₂ -mapping threshold for PCa/csPCa detection was for TZ 81/86 msec (J = 0.929/1.0), and for PZ 110 msec (J = 0.834/0.905). Quantitative T₂ values of PCa did not correlate significantly with the ISUP grade (r_s  = 0.186; P = 0.226), ADC value (r_s  = 0.138; P = 0.372), or PI-RADS (r_s  = 0.132; P = 0.392).

Quantitative T₂ values could differentiate PCa in TZ and PZ and might support standardization of mpMRI of the prostate. Different thresholds seem to apply for PZ and TZ lesions. However, in the present study quantitative T₂ values were not able to indicate PCa aggressiveness.

2 TECHNICAL EFFICACY: Stage 2.