Decreased Tissue Sodium Concentration in Suspected Prostate Cancer Detected by Internal-Reference 23Na MRI: A Prospective Exploratory Study

Objectives: To evaluate Sodium Magnetic Resonance (23Na MR) images of prostate cancer (PCa) and quantify tissue sodium concentration (TSC) based on internal references. Methods: Forty-six patients with clinically suspected prostate cancer were included into a prospective study. The patients underwent multiparametric MRI and an additional 23Na MRI examination of the prostate, performed at 3T (Magnetom Skyra, Siemens Healthineers, Erlangen, Germany) using a dual-tuned 1H/23Na body-coil (Rapid Biomedical, Rimpar, Germany) to acquire a 3D radial density-adapted 23Na sequence. Three-dimensional regions of interest (ROI) were defined within the femoral blood vessels, which were used as an internal reference for TSC quantification. Prostate zones and tumor ROIs were defined and TSC was evaluated for each ROI. Results: TSC quantification based on femoral blood vessels demonstrated good stability since mean absolute TSC difference between right and left regions of interest in the blood vessels was 3.3 ± 2.2 mM. TSC in the peripheral zone (40.7 ± 6.0 mM) was significantly higher than in the transition zone (37.5 ± 5.7 mM). Nine suspicious lesions (PI-RADS 4 and 5) were identified in eight men, all with biopsy-proven PCa with Gleason scores of ≥3 + 3. TSC in prostate cancer was significantly lower than in contralateral healthy regions, 32.2 ± 5.5 mM and 36.1 ± 3.9 mM, respectively (p = 0.018). Conclusions: TSC quantification of prostate tissue based on internal references is feasible and reliable. TSC was significantly decreased within prostate cancer, which represents a quantitative imaging biomarker that could potentially improve PCa characterization and risk stratification.