Feasibility of MR-Guided PET Reconstruction in Detection of Focal Cortical Dysplasia.

Focal cortical dysplasia (FCD) is one of the most prevalent and difficult to detect structural etiologies of epilepsy. Recent advancements in MRI technology have enhanced detectability of FCD, yet many remain undiagnosed by MRI. FDG-PET may increase detection rates when utilized alongside MRI, yet PET continues to be underutilized beyond temporal lobe epilepsy, likely due to challenges in identifying subtle cortical lesions. Hybrid PET/MR systems present an opportunity to improve image quality and lesion detection, but benefits of hybrid PET/MR in epilepsy beyond workflow advantages are not well established. This feasibility study assesses the potential of a prototype MR-guided PET reconstruction that integrates event-by-event motion correction, enhanced point spread function modeling, regularization techniques, and MR-guided reconstruction algorithm. We demonstrate enhancements in cortical definition and increased conspicuity of FCD in FDG-PET. The combined reconstruction approach provides a distinct advantage for PET/MR, thereby helping to realize the full potential of hybrid PET/MR systems.ABBREVIATIONS: FCD = focal cortical dysplasia; FWHM = full width at half maximum; OSEM = ordered subset expectation maximization; BSREM = block sequential regularized expectation maximization.