Abstracts

Rationale: Magnetic resonance fingerprinting (MRF) is an advanced quantitative MR technique that can acquire multiparametric tissue maps simultaneously based on a dictionary-matching algorithm (Ma et al., Nature 2013). The quantitative nature of the MRF framework makes it well suited for assessing whole-brain tissue property changes in epileptic patients. Here we aim to use a high-resolution 3D MRF protocol to examine T1 and T2 changes from pharmacoresistant focal epilepsy patients with negative MRI, through a voxel-wise group-analysis method.

Methods: We included 30 pharmacoresistant focal epilepsy patients with negative MRI by official radiology report on standard epilepsy protocol, as well as 40 health controls (HCs). MRI scans were performed using a Siemens 3.0 T Prisma scanner with a 3D whole-brain MRF sequence (1 mm³ isotropic voxels, Ma et al., JMRI 2019). Dictionary-based reconstruction of the MRF T1 and T2 maps was performed. A T1w image data set was synthesized from the MRF maps, which was perfectly aligned with the T1 and T2 maps for the next steps of processing. Following skull stripping, the synthesized T1w image was aligned to the MNI standard space via SyN in Advanced Normalization Tools (ANTs); the transformation matrices were then applied to the T1 and T2 maps. T1 and T2 maps for patients with right-sided epilepsy were flipped to the left side, so that for all the analyses, left indicated ipsilateral and right indicated contralateral. The FSL Threshold-Free Cluster Enhancement (TFCE) method was used to assess the significant differences in T1 and T2 maps between patients and HCs. Comparisons were performed with gray matter (GM) and white matter (WM) masks separately. Family-wise error (FWE) rate was used for multiple comparison correction with significant level defined as P < 0.05. Spearman’s correction test was used to examine the relationship between clinical characteristics and significant MRF findings.