Multimodal magnetic resonance imaging and spectroscopy for prostate cancer screening and staging

Introduction Multi-modal magnetic resonance imaging (MRI) combining T2-weighted imaging with advanced techniques such as diffusion-weighted imaging (DWI), dynamic contrast and proton spectroscopy is a promising tool for prostate cancer screening, staging and treatment planning. Purpose Evaluation and optimization of multi-modal MRI techniques for prostate cancer screening, staging and treatment planning. Materials and methods Participants at high risk of prostate cancer underwent MRI scans including T2-weighted imaging, DWI using echo planar readout, 3D chemical shift imaging (CSI) and dynamic contrast enhanced imaging on a 3T Siemens scanner with data acquisition using spine and surface coils only. The results were analyzed using vendor-supplied and in-house software and scored according to the “Prostate imaging reporting and data system (PI-RADS)” scoring system. Results Despite the promise of spectroscopic biomarkers as a diagnostic tool, the CSI spectra acquired using standard sequences proved generally of insufficient quality for reliable biomarker estimation. Scanner produced metabolite maps proved highly variable and prone to misidentification of metabolites due to poorly resolved peaks. Apparent diffusion coefficient (ADC) maps appeared diagnostically more useful although low signal and noise floor issues at higher b-values also affected the estimation of ADCs and apparent kurtosis observed at low b-values, casting some doubt on the reliability of high kurtosis values reported in the literature for prostate diffusion kurtosis imaging (DKI). Conclusion Reliable quantification of spectroscopic biomarkers for prostate cancer requires improved protocols for CSI and spectroscopy. Apparent kurtosis observed for diffusion weighted images acquired at low maximum b-values are require further validation.