Cerebral vasculopathy in sickle cell anemia: Diagnostic contribution of positron emission tomography

Children with sickle cell anemia (SS) have an increased risk for cerebral v asculopathy with stroke (CVA) and cognitive impairment. The present study e xamines the extent to which adding positron emission tomography (PET) to ma gnetic resonance imaging (MRI) can improve the detection of cerebral vascul opathy. Whereas MRI has been the prime modality for showing anatomical lesi ons, PET excels at assessing the functional metabolic state through glucose utilization 2-deoxy-2 [F-18] fluoro-D-glucose (FDG) and microvascular bloo d flow ([O-15]H2O). Forty-nine SS children were studied. Among them, 19 had clinically overt CVA, 20 had life-threatening hypoxic episodes or soft neu rologic signs, and 10 were normal based on neurological history and examina tion. For the entire sample of 49 subjects, 30 (61%) had abnormal MRI findi ngs, 36 (73%) had abnormal PET findings, and 44 (90%) showed abnormalities on either the MRI or the PET or both. Of the 19 subjects with overt CVA, 17 had abnormal MRI (89%), 17 had abnormal PET (89%), and 19 (100%) had eithe r abnormal MRI or PET or both. Among the 20 subjects with soft neurologic s igns, 10 (50%) had abnormal MRI, 13 (65%) had abnormal PET, and 17 (85%) ha d abnormal MRI and/or PET. Six (60%) of the 10 neurologically normal subjec ts had abnormal PET. Among the 30 subjects with no overt CVA, 25 (83%) demo nstrated imaging abnormalities based on either MRI or PEI or both, thus, si lent ischemia. Lower than average full-scale intelligence quotient (FSIQ) w as associated with either overt CVA or silent ischemic lesions. Four subjec ts who received chronic red blood cell transfusion showed improved metaboli c and perfusion status on repeat PET scans. In conclusion, (1) the addition of PET to MRI identified a much greater proportion of SS children with neu roimaging abnormalities, particularly in those who had no history of overt neurologic events. (2) PET lesions are more extensive, often bihemispheric, as compared with MRI abnormalities. (3) PET may be useful in management as a tool to evaluate metabolic improvement after therapeutic interventions, and (4) the correlation of PET abnormalities to subsequent stroke or progre ssive neurologic dysfunction requires further study. (C) 1999 by The Americ an Society of Hematology.