Feasibility of PI-RADS Compliant Prostate MRI at 0.55T

PurposeTo demonstrate the feasibility of prostate MRI at low-field and provide an optimised low-field prostate MRI protocol. MethodsWe acquired bi-parametric prostate MRI in 15 healthy male volunteers (mean age 62 years, 95% CI 57-67.5), including tri-planar T2-weighted imaging (WI) and axial diffusion weighted imaging (DWI), with parameters adhering to PI-RADS guidelines. Deep learning reconstruction (DLR) was used to enhance image quality. SNR and CNR were measured in the prostate peripheral zone (PZ) and transitional zone (TZ). SNR was compared between T2-WI with and without DLR, between DWI data acquired with different b-values, and between different calculated b-value images. Radiologists assigned PI-QUAL qualitative image scores. ResultsThe acquisition time (minutes:seconds) was 4:02 for axial T2-WI and 6:32 for DWI. Axial T2-WI had a median (IQR) SNR of 8.72 (7.27-9.67) in the TZ and 12.84 (12.00-15.87) in the PZ. CNR between the PZ and TZ was 5.84 (4.06-6.82). 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. Median apparent diffusion coefficient (ADC) values were 1.70 and 1.44x10-3 mm2 s-1 in the PZ and TZ, respectively. All participants had at least acceptable diagnostic quality (PI-QUAL score[&ge;]2/3), of which ten (67%) had optimal diagnostic quality (PI-QUAL score=3/3). ConclusionProstate MRI is feasible at low-field, providing clinically acceptable acquisition times and diagnostic quality images.