MR measurement of luminal water in prostate gland: Quantitative correlation between MRI and histology

To determine the relationship between parameters measured from luminal water imaging (LWI), a new magnetic resonance imaging (MRI) T₂ mapping technique, and the corresponding tissue composition in prostate.

In all, 17 patients with prostate cancer were examined with a 3D multiecho spin echo sequence at 3T prior to undergoing radical prostatectomy. Maps of seven MR parameters, called N, T_2-short , T_2-long , A_short , A_long , geometric mean T₂ time (gmT₂ ), and luminal water fraction (LWF), were generated using nonnegative least squares (NNLS) analysis of the T₂ decay curves. MR parametric maps were correlated to digitized whole-mount histology sections. Percentage area of tissue components, including luminal space, nuclei, and cytoplasm plus stroma, was measured on the histology sections by using color-based image segmentation. Spearman's rank correlation test was used to evaluate the correlation between MR parameters and the corresponding tissue components, with particular attention paid to the correlation between LWF and percentage area of luminal space.

N, T_2-short , A_long , gmT₂ , and LWF showed significant correlation (P < 0.05) with percentage area of luminal space and stroma plus cytoplasm. T_2-short and gmT₂ also showed significant correlation (P < 0.05) with percentage area of nuclei. Overall, the strongest correlation was observed between LWF and luminal space (Spearman's coefficient of rank correlation = 0.75, P < 0.001).

Results of this study show that LWF measured with MRI is strongly correlated with the fractional amount of luminal space in prostatic tissue. This result suggests that LWI can potentially be applied for evaluation of prostatic diseases in which the extent of luminal space differs between normal and abnormal tissues.

1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:861-869.