Magnetic resonance imaging
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7.0 Tesla (T) high-resolution diffusion tensor imaging (DTI) can supply information on changing microstructures in cranial nerves. We investigated DTI parameters and the feasibility of DTI criteria for diagnosing trigeminal neuralgia (TN). In this study, 14 patients (28 hemispheres) of mean age 49.0 years (range, 31-64) with TN underwent DTI using 7.0 TMRI. ⋯ Nuclei were not significantly different among patients with TN. Barrow Neurological Institute (BNI) pain scores did not correlate with affected sides. 7.0 T DTI was useful for detecting neurovascular compression in patients with TN. The increased signal-to-noise ratio provided by 7 T MRI should be advantageous for increasing spatial resolution to detect microstructure changes to trigeminal nerves in patients with TN.
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Quantitative MRI (qMRI) provides surrogate brain maps of myelin and iron content. After spatial normalization to a common standard brain space, these may be used to detect altered myelination and iron accumulation in clinical populations. Here, volumetric and combined volumetric and surface-based (CVS) normalization were compared to identify which procedure would afford the greatest sensitivity to inter-regional differences (contrast), and the lowest inter-subject variability (under normal conditions), of myelin- and iron-related qMRI parameters, in whole-brain group-level studies. ⋯ Across cortical voxels, the inter-individual variability of myelin and iron qMRI maps were comparable between CVS (with no smoothing) and DARTEL-VBQ (with smoothing). CVS normalization of qMRI maps preserves higher myelin and iron contrast than DARTEL-VBQ over the entire brain, while exhibiting comparable variability in the cerebral cortex without extra smoothing. Thus, CVS may prove useful for detecting small microstructural differences in whole-brain group-level qMRI studies.