Characterization of clinical human prostate cancer lesions using 3.0-T sodium MRI registered to Gleason-graded whole-mount histopathology

Abstract

Background: Overtreatment of prostate cancer (PCa) is a healthcare issue. Development of noninvasive imaging tools for improved characterization of prostate lesions might reduce overtreatment.

Purpose: To measure the distribution of tissue sodium concentration (TSC), proton T₂ -weighted signal, and apparent diffusion coefficient (ADC) values in human PCa and to test the presence of a correlation between regional differences in imaging metrics and the Gleason grade of lesions determined from histopathology.

Study type: Cross-sectional.

Subjects: Ten men with biopsy-proven PCa.

Sequences/field strength: Sodium, proton T₂ -weighted, and diffusion-weighted MRI data were acquired using Broad-Band 3D-Fast-Gradient-Recalled, 3D Cube (Isotropic 3D-Fast-Turbo-Spin-Echo acquisition) and 2D Spin-Echo sequences, respectively, with a 3.0T MR scanner.

Assessment: All imaging data were coregistered to Gleason-graded postprostatectomy histology, as the standard for prostate cancer lesion characterization. Regional TSC and T₂ data were assessed using percent changes from healthy tissue of the same patient (denoted ΔTSC, ΔT₂ ).

Statistics: Differences in ΔTSC, ADC, and ΔT₂ as a function of Gleason score were analyzed for each imaging contrast using a one-way analysis of variance or a nonparametric t-test. Correlations between imaging data measures and Gleason score were assessed using a Spearman's ranked correlation.

Results: Evaluation of the correlation of ΔTSC, ADC, and ΔT₂ datasets with Gleason scoring revealed that only the correlation between ΔTSC and Gleason score was statistically significant (r_s = 0.791, p < 0.01), whereas the correlations of ADC and ΔT₂ with Gleason score were not (r_s = -0.306, p = 0.079 and r _s = -0.069, p = 0.699, respectively). In addition, all individual patients showed monotonically increasing ΔTSC with Gleason score.

Data conclusion: The results of this preliminary study suggest that changes in TSC, assessed by sodium MRI, has utility as a noninvasive imaging assay to accurately characterize PCa lesions. Sodium MRI may provide useful complementary information on mpMRI, which may assist the decision-making of men choosing either active surveillance or treatment.

Level of evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1409-1419.

Keywords: lesion characterization; multiparametric MRI; prostate cancer; sodium MRI; tissue sodium concentration; whole-mount histopathology.