Arterial Spin Labeling Magnetic Resonance Evaluates Changes of Cerebral Blood Flow in Patients with Mild Traumatic Brain Injury.

OBJECTIVES:The patients with mild traumatic brain injury (mTBI) accounts for more than 80% of the patients with brain injury. Most patients with mTBI have no abnormalities in CT examination. Therefore, most patients choose to self-care and recover rather than seeking medical treatment. In fact, mTBI may result in persistent cognitive decline and neurobehavioral dysfunction. In addition, changes occurred in neurochemistry, metabolism, and cells after injury may cause changes in cerebral blood flow (CBF), which is one of the causes of secondary injury and slow brain repair. This study aims to evaluate the changes of CBF with the progression of the disease in patients with mTBI based on arterial spin labeling (ASL) magnetic resonance imaging technology. METHODS:In the outpatient or emergency department of the Second Affiliated Hospital of Wenzhou Medical University, 43 mTBI patients were collected as an mTBI group, and 43 normal subjects with age, gender, and education level matching served as a control group. They all received clinical neuropsychology and cognitive function evaluation and magnetic resonance imaging. In the mTBI group, 22 subjects were followed up at acute phase, 1 month, 3 months, and 12 months. Based on the control group, the abnormal regions of CBF in the whole brain of mTBI patients were analyzed. The abnormal regions were taken as the regions of interest (ROI). The correlation of the values of the CBF in ROIs with clinical indications, cognitive function, and the changes of CBF in ROI at each time point during the follow-up were analyzed. RESULTS:Compared with the control group, the CBF in the bilateral dorsolateral superior frontal gyrus and auxiliary motor areas in the cortical region, as well as the right putamen, caudate nucleus, globus pallidus, and parahippocampus in the subcutaneous regions in the acute phase of the mTBI group were significantly increased (all P<0.01, TFCE-FWE correction). The analysis results of correlation of CBF with neuropsychology and cognitive domain showed that in the mTBI group, whole brain (r=0.528, P<0.001), right caudate nucleus (r=0.512, P<0.001), putamen (r=0.486, P<0.001), and globus pallidus (r=0.426, P=0.006) values of the were positively correlated with Backward Digit Span Test (BDST) score (reflectting working memory ability), and the right globus pallidus CBF was negatively correlated with the Post-Traumatic Stress Disorder Cheeklist-CivilianVersion (PCL-C) score (r=-0.402, P=0.010). Moreover, the follow-up study showed that abnormal CBF in these areas had not been restored. The correlation of CBF was negatively correlated with PCL-C and BDST at 1 months, 3 months, and 12 months (all P>0.05). CONCLUSIONS:The elevated CBF value is one of the stress characteristics of brain injury in the mTBI patients at the acute phase. There is abnormal elevation of CBF values in multiple cortex or subcortical areas. Multi-time point studies show that there is no obvious change of CBF in abnormal areas, suggesting that potential clinical treatment is urgently needed for the mTBI patients.