H. Stevens et al., CO-57 AND TECHNETIUM-99M-HMPAO-LABELED LEUKOCYTES FOR VISUALIZATION OF ISCHEMIC INFARCTS, The Journal of nuclear medicine, 39(3), 1998, pp. 495-498
Previous studies have shown the usefulness of divalent cobalt isotopes
to visualize cerebral damage after stroke, The site of accumulation o
f cobalt ion is unknown but may be explained by neuronal influx, analo
gous to that of calcium ion. Additionally, uptake may be due to infilt
rating leukocytes or protein-bound cobalt. The aims of this study were
to compare Co-57-SPECT with leukocyte SPECT and to compare the SPECT
findings with clinical outcome as scored by the Orgogozo scale. Materi
als: Ten patients with a CT scan positive for middle cerebral artery i
nfarcts were included in the study (7 men, 3 women; mean age 70 yr), T
echnetium-99m leukocyte and cobalt-SPECT (interval 2-4 days) were made
with a double-headed gamma camera, after the injection of 10-15 mCi T
c-99m-HMPAO-labeled leukocytes and 0.4 mCi Co-57, respectively, Scans
were performed within 5-30 days after onset of the first symptoms. Reg
ions of interest (ROI) containing the area of infarction in the slices
displaying enhanced radioactivity or the middle cerebral artery (MCA)
region in four successive slices were defined for calculating enhance
ment ratios. The (TC)-T-99m leukocyte enhancement ratio (LER) and coba
lt enhancement ratio (CER) were defined as the quotient of radioactivi
ty in the ROI and an identical contralateral ROI. The MCA stroke-scale
according to Orgogozo was used to assess neurological deficits at the
time of scanning and discharge. Results: Cobalt-57 and Tc-99m-HMPAO s
howed uptake in the infarcted brain area in five patients; the quantit
ative uptake in the infarcted brain area of the two tracers correlated
significantly (p < 0.05). Both the LER and the CER correlated signifi
cantly (p < 0.05) with the Orgogozo score at the time of scanning. Onl
y the LER correlated significantly (p < 0.05) with the Orgogozo score
at discharge. Conclusion: Uptake of cobalt and leukocytes in the peri-
infarct tissue suggests that Co-57 may visualize a component of the in
flammatory response. Divalent Co-57 may be convenient to predict clini
cal prognosis after stroke.