Comparison of 99mTc-annexin A5 with 18F-FDG for the detection of atherosclerosis in ApoE-/- mice.
OBJECTIVE
(99m)Tc-annexin A5, a marker of ongoing apoptosis, and (18)F-FDG, a marker of the increased metabolism of inflammatory cells, are supposed to be useful in the detection of metabolically active atheroma. This study reports a comparison of the intralesional distribution of these tracers in relation to lesion development in ApoE-/- mice.


METHODS
Male ApoE-/- mice (n = 12-14/group) were maintained on a Western-type diet after the age of 5 weeks. At 25 weeks, (99m)Tc-annexin A5 or (18)F-FDG was injected and the aortas were harvested for autoradiography (ARG) and Oil Red O staining. Regional radioactivity accumulation was compared in relation to the Oil Red O staining score (ranging from 0 to 3, a semiquantitative parameter for evaluating lesion development).


RESULTS
Both (99m)Tc-annexin A5 and (18)F-FDG showed preferential uptake into atherosclerotic lesions, with higher uptake levels for (18)F-FDG (mean, 56.07 %IDxkg/m(2)) than for (99m)Tc-annexin A5 (mean, 10.38 %IDxkg/m(2)). The regional uptake levels of each tracer correlated with the Oil Red O staining score (r = 0.65, p < 0.05 for (99m)Tc-annexin A5; r = 0.56, p < 0.05 for (18)F-FDG). The uptake ratios of advanced lesions (score >0.5) to early lesions (score <0.5) were significantly higher for (99m)Tc-annexin A5 than for (18)F-FDG (f = 4.73, p = 0.03).


CONCLUSIONS
Both (99m)Tc-annexin A5 and (18)F-FDG accumulate in atherosclerotic lesions and correlate with the severity of each lesion. The higher absolute uptake levels of (18)F-FDG may be advantageous for lesion detection, whereas the preferential uptake of (99m)Tc-annexin A5 in advanced lesions may be a useful indicator of late-stage lesions or vulnerable plaque transformation.
Zhao
Yan
Y
Department of Nuclear Medicine, Graduate School of Medicine, Hokkaido University, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan.
Kuge
Yuji
Y
Zhao
Songji
S
Morita
Koichi
K
Inubushi
Masayuki
M
Strauss
H William
HW
Blankenberg
Francis G
FG
Tamaki
Nagara
N
D000818:Animals; D017304:Annexin A5; D001057:Apolipoproteins E / Q000172:deficiency*; D050197:Atherosclerosis / Q000000981:diagnostic imaging*; D004195:Disease Models, Animal; D019788:Fluorodeoxyglucose F18; D051379:Mice; D018345:Mice, Knockout; D015609:Organotechnetium Compounds; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D017304:Annexin A5; D001057:Apolipoproteins E; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C117287:technetium Tc 99m HYNIC annexin V; D019788:Fluorodeoxyglucose F18