Novel 3D DWI for Detection and Characterization of Prostate Cancer in Men with Pelvic Metal Implants

Project Summary Prostate cancer is the most common malignancy and the second leading cause of cancer-related mortality in men in the United States. The American Urological Association recommends the use of multiparametric magnetic resonance imaging (mpMRI) for diagnosis and disease management in all men at high risk for prostate cancer. mpMRI is also beneficial in men: 1) with an increasing prostate-specific antigen (PSA) following an initial negative prostate biopsy; 2) during longitudinal follow-up in active surveillance for biopsy- proven low-risk prostate cancer; and 3) for guidance of locally targeted therapies including cryotherapy, high intensity focused ultrasound (HIFU), MR-guided transurethral ultrasound ablation (TULSA), and emerging radioligand targeted treatments for intermediate to high-risk cancers. These recommendations are only realizable through accurate localization and characterization of individual prostate lesions on MRI, which is significantly challenging in men with pelvic metal implants. This is important since the incidence of prostate cancer increases substantially over 50 years of age and in parallel, the prevalence of hip replacement surgery also increases in that age group (estimated to reach ~4 million by 2030 in the US). Most of the metal implants in current clinical use are MR compatible, however, they distort the local magnetic field (B0) causing significant signal loss and image distortion. This is particularly problematic with echo-planar based diffusion-weighted imaging (EP-DWI), rendering these images non-diagnostic. This is a major limitation since DWI, according to the prostate imaging reporting and data system (PI-RADS) classification, is the pivotal sequence for lesion detection and characterization in the peripheral zone, where 70-75% of prostate cancers arise. To address this unmet clinical need, we propose to establish a 3D turbo spin echo (TSE) based DWI that is robust and can be widely implemented across all MR scanners. This is built upon our recently introduced novel acquisition and reconstruction strategy utilizing variable density Cartesian acquisition with spiral profile reordering (VD- CASPR). The volumetric acquisition of 3D VD-CASPR-DWI provides higher signal to noise ratio and the TSE readout improves the robustness to B0 inhomogeneities. This provides superior image quality and enables the visualization of the entire prostate gland without image distortions facilitating accurate detection and characterization of prostate lesions in men with pelvic metal implants. We will optimize the novel 3D VD- CASPR-DWI in phantoms and in-vivo prostate imaging of healthy volunteers. We will then validate this technique in 20 patients without and 20 patients with pelvic metal implants, evaluated for known or suspected prostate cancer. The successful outcome of this project will be an optimized mpMRI with our novel 3D VD- CASPR-DWI that provides pertinent clinical information for better management of prostate cancer patients and subsequently improve their quality of life and overall survival.