Abstract 110

Purpose: To evaluate the feasibility of performing measurements of cerebral blood flow (CBF) in human infants with MRI flow measurement of the neck vessels.

Material and Methods: Eighteen infants, GA 26-41 (mean 32.3) weeks, chronological age 2-72 (median 9) days. Eleven infants were healthy. Flow was measured in the carotid and vertebral arteries and jugular veins(identified on an MR angiogramme) with a cardiac gated phase mapping technique on a 1.5 T MRI system. One flow measurement lasted 3-4 minutes, in some infants, two or more measurements were performed and averaged. Vessel flow was calculated from the mean phase shift of a region of interest through a cardiac cycle, cerebral blood flow was calculated from arterial vessel flow and cerebral volume, derived semi-automatically from T2-weighted images.

Results: Data from two infants had to be discarded because of motion artifacts. In some individuals, not all vessels could be sectioned transverse, and identification was difficult. Calculated flow ranged from 13.1ml/100ml tissue/min in a preterm infant who subsequently died to 52.1ml/100ml tissue/min in a term infant with a cerebral hemorrhage. In the healthy infants, variability was high, flow in 6 infants of 31-33 weeks post-menstrual age, CBF ranged from 13.2 to 37.8 (mean 22.4) ml/100ml tissue/min.

Conclusion: CBF in infants can be measured with MRI phase mapping, adding global CBF values to the spectrum of information which can be derived from a single examination. Potential sources of error are non-perpendicular positioning of the imaging slice and partial volume effects of the relatively small vessels. Future studies could include comparisons with other CBF measurement modalities.