MRA of the intracranial circulation in asymptomatic patients with sickle cell disease

MR angiography (MRA) provides a mechanism for non-invasively studying blood flow, thus providing a new opportunity to study the intracranial circulation in asymptomatic sickle cell disease (SCD) patients. Although conventional angiography is the gold standard for the depiction of vascular anatomy, this is too invasive for an asymptomatic population.

To establish the range of appearances in asymptomatic SCD patients and to correlate brain MRI results (either sub-clinical abnormalities or normal brain parenchyma) with the MRA findings.

Brain MRI and MRA of the intracranial circulation was performed on 22 patients (13 male and 9 female, median age 7.5 years, range 1.3-20 years). Fourteen were homozygous SS and eight were SC. The median haematocrit at the time of MRI was 25.9 (range 13.8-33.3).

On MR imaging, four patients had infarcts in eight vascular territories (six anterior and two posterior). In 3/4 of anterior vascular territories with infarction, long ( >/= 6 mm) segments of abnormal signal were seen at the internal carotid artery bifurcation with associated reduced distal flow. Short focal areas of abnormal signal were commonly seen where vessels branched, bifurcated or curved and were not associated with infarcts. These areas probably represent turbulence-related dephasing secondary to high velocity flow found in SCD.

Long segments ( >/= 6 mm) of abnormal signal with reduced distal flow correlated with sub-clinical infarction.