Improving Multiparametric MR-Transrectal ultrasound Guided Fusion Prostate biopsies with Hyperpolarized 13C Pyruvate Metabolic imaging: A technical development study

Purpose To develop techniques and establish a workflow using hyperpolarized carbon-13 (C-13) MRI and the pyruvate-to-lactate conversion rate (k(PL)) biomarker to guide MR-transrectal ultrasound fusion prostate biopsies. Methods The integrated multiparametric MRI (mpMRI) exam consisted of a 1-min hyperpolarized C-13-pyruvate EPI acquisition added to a conventional prostate mpMRI exam. Maps of k(PL) values were calculated, uploaded to a picture archiving and communication system and targeting platform, and displayed as color overlays on T-2-weighted anatomic images. Abdominal radiologists identified C-13 research biopsy targets based on the general recommendation of focal lesions with k(PL) >0.02(s(-1)), and created a targeting report for each study. Urologists conducted transrectal ultrasound-guided MR fusion biopsies, including the standard H-1-mpMRI targets as well as 12-14 core systematic biopsies informed by the research C-13-k(PL) targets. All biopsy results were included in the final pathology report and calculated toward clinical risk. Results This study demonstrated the safety and technical feasibility of integrating hyperpolarized C-13 metabolic targeting into routine H-1-mpMRI and transrectal ultrasound fusion biopsy workflows, evaluated via 5 men (median age 71 years, prostate-specific antigen 8.4 ng/mL, Cancer of the Prostate Risk Assessment score 2) on active surveillance undergoing integrated scan and subsequent biopsies. No adverse event was reported. Median turnaround time was less than 3 days from scan to C-13-k(PL) targeting, and scan-to-biopsy time was 2 weeks. Median number of C-13 targets was 1 (range: 1-2) per patient, measuring 1.0 cm (range: 0.6-1.9) in diameter, with a median k(PL) of 0.0319 s(-1) (range: 0.0198-0.0410). Conclusions This proof-of-concept work demonstrated the safety and feasibility of integrating hyperpolarized C-13 MR biomarkers to the standard mpMRI workflow to guide MR-transrectal ultrasound fusion biopsies.