Sub‐millimeter isotropic MRI for segmentation of subcortical brain regions and brain visualization

Abstract

Purpose: To evaluate a rapid sub-millimeter isotropic spoiled gradient-echo (nonselective SPGR) to facilitate the brain subcortical segmentation and the visualization of brain volume compared with the commonly accepted inversion recovery-prepared SPGR (SPGR-IR) technique. Materials and Methods:The feasibility of the nonselective SPGR was evaluated for two segmentation algorithms. FAST was used to segment the brain into constituent tissue classes (white matter, gray matter, cerebrospinal fluid) and FreeSurfer was used to segment specific subcortical structures (hippocampus, caudate, putamen, and thalamus). Localized apparent signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) values for nonselective SPGR and the SPGR-IR were compared for the studied subcortical regions. The three-dimensional volume rendering was generated to evaluate the nonselective SPGR and the SPGR-IR for brain visualization.Results: In basal ganglia regions, nonselective SPGR allows for consistent segmentation results for both FAST and FreeSurfer. This sequence also better differentiated gray/white matter compared with SPGR-IR. An approximate two-fold improvement of image quality in apparent SNR and CNR was indicated for subcortical brain anatomical structures with nonselective SPGR versus SPGR-IR. The nonselective SPGR improved clarity and yielded a more realistic depiction of the brain surface for visualization compared with SPGR-IR. Conclusion:Compared with SPGR-IR, nonselective SPGR allows for consistent segmentation results for basal ganglia regions and improved clarity for visualization of the brain.

In vivo magnetic resonance imaging at 11.7 Tesla visualized the effects of neonatal transection of infraorbital nerve upon primary and secondary trigeminal pathways in rats

“…In recent years, a remarkable progress of MRI techniques has made possible to visualize fine morphology of nervous system at the sub-millimeter scale (Jahnke et al, 2007;Wu et al, 2010). Those studies revealed that the trigeminal nerve consists of three components in rats (Does and Gore, 2002), nerve tracts of the sciatic nerve were visualized with a contrast agent in rats (Chen et al, 2011) and the volume of dorsal root ganglia decreased after peripheral nerve injury (West et al, 2007).…”

3 versus 7 Tesla Magnetic Resonance Imaging for parcellations of subcortical brain structures

“…MRI scans through the use of isotropic voxels and QSM do indeed allow for more accurate visualization of the surgical target, a result that is within reach for clinical application without the need for the investment in new hardware [68,69]. We would like to note that despite improved anatomical orientation, individual variation in the internal structure of the STN may continue to require awake testing of patients during surgery to obtain the desired clinical effect.…”