Assessment of cerebral blood flow using FAIR-arterial spin labelling on fetal brain: clinical feasibility and preliminary results

The arterial spin labelling is a non-contrast MRI technique allowing blood flow quantification in any kind of tissue. There are no studies exploring the fetal brain by ASL technique. The objectives of this study were: (1) to evaluate the feasibility of cerebral blood flow (CBF) measures with FAIR-Arterial Spin Labelling (FAIR-ASL) on the fetal brain in normal pregnancies, (2) to describe the CBF values depending on the region of interest and the gestational age. We conducted a prospective study between January 2023 and March 2023 with the LUMIERE Platform in Necker Hospital (Paris, France). We included patients between 28 and 35+6 weeks of gestation who had normal prenatal ultrasound scans. All patients underwent MRI scans on a 1.5 Tesla MRI scanner (General Electric) without sedation. The FAIR-ASL parameters were as follow: TR/TE 7000/27.2ms; FOV 24x24cm2; number of slice 1; pixel size 2.8x2.8 mm2; matrix 128x128; slice thickness 10 mm; inversion thickness 40mm; QUIPSS thickness 70mm; post-labelling delay (PLD) 1500ms, acquisition time: 3.37minutes. CBF values were extracted from regions of interest (ROI) centred on the grey matter, white matter, basal ganglia and cerebellum. Two additional ROI were drawn manually including the total brain region and the cerebellar region. Cases affected by motion artefacts were excluded. Sixteen patients were included at a median gestational age (GA) of 34.4 [33.1; 35.2] weeks of gestation. One patient was excluded because of fetal movements. Acquisition of ASL parameters were feasible in 100% of the remaining cases (15/15). The median CBF value in total brain was 83.0 ml/min/100g [77.5; 94.0]. We observed a significantly lower CBF in the white matter (p = 0.023). Increasing GA was correlated with increasing CBF values in the grey matter (r = 0.49, p = 0.028) and basal ganglia (r = 0.46, p = 0.041). This study shows for the first time that measurement of CBF by FAIR-ASL is feasible on normal fetuses. This may prove extremely useful in managing IUGR fetuses and high-risk pregnancy.