Fast and High-Resolution luminal water imaging for prostate cancer diagnosis

This study aims to address the limitation of long acquisition times in luminal water imaging (LWI), a promising noninvasive MRI technique for prostate cancer detection and grading, by implementing an accelerated multi-echo spin-echo method termed T2 mapping using echo merging plus k-t undersampling with reduced flip angles (TEMPURA).

TEMPURA enables faster acquisition through echo merging, k-t undersampling, and reduced refocusing flip angles. A prospective study was conducted on 24 patients (age 59-75 years) with biopsy-proven prostate cancer. Imaging was performed on a 3 T MRI system, comparing two TEMPURA-based LWI sequences-Fast (standard resolution) and High-Resolution (HR, doubled spatial resolution)-against a standard LWI sequence (Standard). Luminal water fraction and five additional parameters were compared across the methods. Statistical analyses included Spearman rank correlation, Wilcoxon rank sum test, receiver operating characteristic analysis, Bland-Altman plots, and Delong tests.

Compared to Standard, Fast reduced the acquisition time from 8.3 to 2.8 min, whereas HR reduced it to 5.4 min and doubled spatial resolution. Both Fast and HR showed high correlation with Standard for luminal water fraction (r = 0.97/0.90 in peripheral zone, r = 0.91/0.93 in transition zone), with low bias (0.014/0.018 in peripheral zone, 0.024/0.024 in transition zone) and no significant differences (p = 0.05-0.84/0.08-0.51). No significant difference was observed in area under the curve values between Fast/HR and Standard among all parameters (p = 0.05-0.87).

The acceleration method greatly reduced the acquisition time and increased the spatial resolution of LWI. Compared with the Standard acquisition, both the Fast and HR methods showed a high correlation for LWI measurements and consistent diagnostic performance in detecting malignant lesions.