Evidence of cranial artery ectasia in sickle cell disease patients with ectasia of the basilar artery.

GOAL: To determine if children with sickle cell disease (SCD) and basilar artery ectasia show evidence of general arterial ectasia.
METHODS: A novel method was used to analyze the base images normally used to reconstruct a magnetic resonance angiogram (MRA). A signal intensity threshold was set empirically to exclude pixels from subcutaneous fat, then base images for each patient were evaluated for the number and relative size of vessel profiles. Data from three SCD patients, imaged before and after transfusion, were analyzed to determine sensitivity of the method to blood flow. We then compared 11 SCD patients with basilar ectasia to 11 age-matched SCD patients with a normal basilar, after excluding patients with clinical stroke.
FINDINGS: Before transfusion, patients have an apparent blood volume 48% higher than after (P<.001). Transfusion reduces apparent blood volume because flow rate is reduced by transfusion and MRA is flow-sensitive. But apparent blood volume was not significantly lower in any individual vessel size class, suggesting that fast flow simply increases vessel conspicuity. Patients with basilar ectasia have an apparent blood volume 62% higher than normal (P<.001). Although this could be due to faster blood flow, apparent blood volume was higher specifically in vessels > or =2 mm in diameter (P<.001), suggesting that small arteries can become generally ectatic in patients with basilar ectasia.
CONCLUSIONS: Basilar ectasia is associated with an increased blood flow rate, generalized arterial ectasia, or both phenomena. This suggests that basilar volume measurements may supplement blood flow velocity measurements as an indicator of stroke risk.