The role of MRA in pediatric sickle cell disease with normal transcranial Doppler imaging velocities

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PurposeThe purpose of this study was to determine the additional information provided by Magnetic Resonance Angiography (MRA) in pediatric sickle cell disease (SCD) patients with normal Transcranial Doppler imaging (TCDI) examinations. MethodsThis cohort study included all pediatric SCD patients over an 18-year period who had no history of stroke and had normal TCDI examinations and subsequently underwent MRA. Routine TCDI inclusive of time-averaged mean of maximum velocities (TAMMV) were assesses and compared with tortuosity on MRA and silent infarct on MRI. Results86 children (52.3% female; mean age 8.7 ± 3.5years) were included. There were 77 patients (89.5%) with Hb-SS disease and 9(10.4%) with HB-S beta-thalassemia. All patients had normal TAMMV (<170 cm/s) on TCDI. 76/86 (88.3%) patients also had one or more velocity readings <70 cm/s, albeit none in the middle cerebral arteries. Posterior cerebral arteries had the lowest velocities, <70 cm/s in 51.7% (right) and 60.9% (left). Silent MRI infarcts were seen in 27/86 (31.4%) patients. No new lesions were identified on follow-up MRI. Although mild vascular tortuosity was appreciated in 31/86 (36.0%) of the patients, there were no steno-occlusive lesions in the circle of Willis. ConclusionsTCDI and MRA are routinely performed for non-invasively evaluating intracranial vascular abnormalities in children with SCD. In SCD children with no history of TIA or stroke, MRA following a normal TCDI examination is unlikely to show vascular abnormality. However, almost a third of these patients show silent infarcts on MRI, unassociated with MRA changes.