W. Reed et al., Role of positron emission tomography in determining the extent of CNS ischemia in patients with sickle cell disease, AM J HEMAT, 60(4), 1999, pp. 268-272
Nearly 25% of patients with sickle cell disease (SCD) experience central ne
rvous system morbidity involving both large and small vessel disease. Optim
al imaging methods for determining the extent of ischemia are not known. Po
sitron emission tomography (PET) has the unique ability to show tissue func
tion as well as structure. Reports concerning patients with non-SCD neurode
generative disorders suggest PET may be useful in determining prognosis. We
compared magnetic resonance imaging, magnetic resonance angiography, and n
europsychological testing with PET prospectively. Six patients with SCD and
a history of stroke, aged 10 to 28, were enrolled. PET studies were perfor
med on an ECAT HR 47 scanner (Siemens/CTI, Knoxville, TN) using 18-F-fluoro
deoxyglucose as a tracer. PET interpretations were conducted in blinded fas
hion. MRI studies found two patients with only small vessel disease and fou
r with both large and small vessel disease. In two of four subjects with la
rge vessel disease, PET showed a corresponding metabolic abnormality and al
so identified an area of hypometabolism extending beyond the anatomical les
ion as shown by MRI. PET did not demonstrate an abnormality corresponding w
ith small vessel disease. Detailed neuropsychological testing demonstrated
cognitive dysfunction in all cases. For some patients, PET may add sensitiv
ity in detecting impaired metabolism in the area surrounding a major vessel
infarct. However, the technique does not appear to be generally useful in
characterizing smalt watershed or deep white matter infarcts. Larger studie
s, to include control subjects and carefully selected un-transfused SCD pat
ients, are needed. A combination of conventional imaging and neuropsycholog
ical testing remains the preferred evaluation for most SCD patients with ne
urologic symptoms. Am. J. Hematol. 60:268-272, 1999. 1999 Wiley-Liss,Inc.