Abstract / Summary
Purpose: To demonstrate the feasibility of prostate MRI at low-field and provide an optimised low-field prostate MRI protocol. Methods: In 15 healthy male volunteers (mean age 62 years, 95% CI 57-68) and 22 patients with suspected prostate cancer (mean age 68 years, 95% CI 64-71), we acquired bi-parametric prostate MRI at 0.55T including tri-planar T2-weighted imaging (WI) and axial diffusion weighted imaging (DWI). Parameters adhered to PI-RADS guidelines and deep learning reconstruction (DLR) was used to enhance image quality. In healthy volunteers, we optimised the protocol based on evaluation of SNR, CNR and qualitative image scores. In patients, we evaluated qualitative image scores and lesion detection performance using 3T as the reference. Results: The acquisition time (minutes:seconds) was 4:02 for axial T2-WI and 6:32 for DWI. In healthy controls, DLR substantially improved T2-WI quality (p<0.05). The optimised DWI protocol had b-values of 50 and 800 s mm-2, with a calculated b-value image at 1500 s mm-2. Twenty-one patients (95%), and all controls, had at least acceptable diagnostic quality (PI-QUAL score[≥]2/3) at low-field MRI. With respect to the 3T reference, two readers detected lesions at low-field with sensitivity of 79% and 75% at the lesion level. At the patient level, the sensitivity was 91% for both readers. Low-field patient-level lesion detection did not significantly differ from 3T (p=0.5). Conclusion: Prostate MRI is feasible at low-field, providing clinically acceptable acquisition times for diagnostic quality images with comparable patient-level lesion detection performance to 3T.