Objective: To assess cerebral blood flow (CBF) changes in patients with mild traumatic brain injury (MTBI) using an arterial spin labelling (ASL) perfusion MRI and to investigate the severity of neuropsychological functional impairment with respect to haemodynamic changes.

Materials and methods: Twenty-one patients with MTBI and 20 healthy controls were studied at 3T MR. The median time since the onset of brain injury in patients was 24.6 months. Both patients and controls underwent a traditional consensus battery of neurocognitive tests. ASL was performed using true fast imaging with steady state precession and a flow-sensitive alternating inversion recovery preparation. Regional CBF were measured in both deep and cortical gray matter as well as white matter at the level of basal ganglia.

Results: The mean regional CBF was significantly lower in patients with MTBI (45.9 ± 9.8 ml/100 g min^-1) as compared to normal controls (57.1 ± 8.1 ml/100 g min^-1; p = 0.002) in both sides of thalamus. The decrease of thalamic CBF was significantly correlated with several neurocognitive measures including processing and response speed, memory/learning, verbal fluency and executive function in patients.

Conclusions: Haemodynamic impairment can occur and persist in patients with MTBI, the extent of which is more severe in thalamic regions and correlate with neurocognitive dysfunction during the extended course of disease.