Test-retest reliability of perfusion of the precentral cortex and precentral subcortical white matter on three-dimensional pseudo-continuous arterial spin labeling

Hypoperfusion of hypothalamic subunits in medication-overuse headache using a 3D PCASL MRI

Hypothalamus is a crucial deep brain area that is responsible for the integration and coordination of various brain functions. The altered perfusion of hypothalamus during headache caused by medication-overuse headache (MOH) was previously unknown. In the current study, the altered perfusion of hypothalamic subregions in MOH patients was investigated using state-of-the-art 3D pseudo-continuous arterial spin labeling (PCASL) MR imaging. In this study, 29 normal controls subjects (NCs) and 29 MOH patients underwent 3D PCASL and brain structural MR imaging. The hypothalamus was automatically segmented into 10 subunits and the volume of each subunit was automatically determined using Freesurfer software (v7.4.1). All segmented hypothalamic subunits were converted to individual hypothalamic subunit masks. The cerebral blood flow (CBF) images were coregistered with the raw brain structural images and resliced. The CBF value of each hypothalamic subunit was extracted from the warped CBF images. The volume and CBF value of each hypothalamic subunit were analyzed using the independent sample T test and Mann-Whitney U test, receiver operating characteristic (ROC) curve analysis, and Pearson and Spearman correlation analysis. Hypothalamic subunits with significantly decreased perfusion were located in the left posterior, left tubular superior, right anterior-inferior, right tubular inferior, right tubular superior, right posterior subunit and the entire right hypothalamus [CBF value for MOH vs NC (mL/100 g·min): 48.41 ± 6.75 vs 54.08 ± 11.47, 44.44 ± 4.79 vs 48.11 ± 7.73, 41.49 (32.90, 61.46) vs 49.38 ± 10.47, 46.62 ± 7.04 vs 53.90 ± 11.75, 42.12 ± 5.74 vs 47.02 ± 9.99, 42.79 ± 5.15 vs 47.93 ± 10.48 and 43.58 ± 5.06 vs 48.65 ± 9.33, respectively] in MOH compared to NC (P < 0.05). ROC analysis for these positive subunits revealed that area under the curve was 0.658-0.693, and ROC curve for left posterior subunit had the highest specificity of 93.10% while the entire right hypothalamus had the highest sensitivity of 72.41%. Further correlation analysis showed that the CBF value of the left posterior, right anterior-inferior, right tubular superior, whole right hypothalamus presented significantly negative correlation with Hamilton Depression Scale (HAMD) score (P < 0.05). Hypoperfusion of hypothalamic subunits may contribute to the understanding of MOH pathogenesis, and the 3D PCASL could be considered as a potential diagnostic and assessment tool for MOH.

White-Matter Lesions and Cortical Cerebral Blood Flow Evaluation by 3D Arterial Spin-Labeled Perfusion MRI in Asymptomatic Divers: Correlation with Patent Foramen Ovale Ocurrence

Cerebral white-matter lesions (cWML) can be caused by dilation of Virchow-Robin spaces or may correspond to true lacunar ischemic lesions. The aim of our study was to evaluate in asymptomatic divers the relationship between the presence of patent foramen ovale (PFO) and cWML, as well as their possible effects on cortical cerebral blood flow (CBF) by magnetic resonance (MRI) through the arterial spin labeling (ASL) sequence. Transthoracic echocardiography was performed for the identification of PFO, and cerebral magnetic resonance including the 3D-ASL sequence for CBF quantification. Thirty-eight divers, with a mean age 45.8 ± 8.6 years, were included. Nineteen healthy volunteers, mean age 41 ± 15.2 years, served as the control group. A total of 28.9% of divers had completed more than 1000 dives. It was found that 26.3% of divers presented with PFO in the echocardiographic study. cWML was evidenced in 10.5% of diver MRI studies. There was no statistically significant relationship between the presence of PFO and cWML (p = 0.95). We observed a lower blood flow in all brain areas assessed by the 3D-ASL sequence in the group of divers, compared with the control group. We did not find statistical differences in CBF as a function of the presence or absence of PFO, number of dives, or cWML evidence.

Cerebral Blood Flow Predicts Recovery in Children with Persistent Post-Concussion Symptoms after Mild Traumatic Brain Injury

Persistent post-concussion symptoms (PPCS) following pediatric mild traumatic brain injury (mTBI) are associated with differential changes in cerebral blood flow (CBF). Given its potential as a therapeutic target, we examined CBF changes during recovery in children with PPCS. We hypothesized that CBF would decrease and that such decreases would mirror clinical recovery. In a prospective cohort study, 61 children and adolescents (mean age 14 [standard deviation = 2.6] years; 41% male) with PPCS were imaged with three-dimensional (3D) pseudo-continuous arterial spin-labelled (pCASL) magnetic resonance imaging (MRI) at 4-6 and 8-10 weeks post-injury. Exclusion criteria included any significant past medical history and/or previous concussion within the past 3 months. Twenty-three participants had clinically recovered at the time of the second scan. We found that relative and mean absolute CBF were higher in participants with poor recovery, 44.0 (95% confidence interval [CI]: 43.32, 44.67) than in those with good recovery, 42.19 (95% CI: 41.77, 42.60) mL/min/100 g gray tissue and decreased over time (β = -1.75; p < 0.001). The decrease was greater in those with good recovery (β = 2.29; p < 0.001) and predicted outcome in 77% of children with PPCS (odds ratio [OR] 0.54, 95% CI: 0.36, 0.80; p = 0.002). Future studies are warranted to validate the utility of CBF as a useful predictive biomarker of outcome in PPCS.