αVβ3 integrin-targeted microSPECT/CT imaging of inflamed atherosclerotic plaques in mice.BACKGROUND
 After 90 min, the animals were imaged via single-photon emission computed tomography (SPECT).  Tracer uptake was significantly higher in ApoE(-/-) mice than in both groups of control mice (1.56 ± 0.33 vs. 0.82 ± 0.24 vs. 0.98 ± 0.11, respectively; P = 0.006).  Furthermore, higher tracer activity was detected via gamma counting in the aorta of hypercholesterolemic mice than in both groups of control mice (1.52 ± 0.43 vs. 0.78 ± 0.19 vs. 0.47 ± 0.31 (99m)Tc-maraciclatide %ID/g, respectively; P = 0.018). 
SPECT
αVβ3 integrin-targeted microSPECT/CT imaging of inflamed atherosclerotic plaques in mice.BACKGROUND
 αVβ3-integrin is expressed by activated endothelial cells and macrophages in atherosclerotic plaques and may represent a valuable marker of high-risk plaques.  We evaluated (99m)Tc-maraciclatide, an integrin-specific tracer, for imaging vascular inflammation in atherosclerotic lesions in mice.


 Apolipoprotein E-negative (ApoE(-/-)) mice on a Western diet (n = 10) and normally fed adult C57BL/6 control mice (n = 4) were injected with (99m)Tc-maraciclatide (51.8 ± 3.7 MBq).  After 90 min, the animals were imaged via single-photon emission computed tomography (SPECT).  While maintained in the same position, the mice were transferred to computed tomography (CT) to obtain contrast-enhanced images of the aortic arch.  Images from both modalities were fused, and signal was quantified in the aortic arch and in the vena cava for subtraction of blood-pool activity.  The aorta was carefully dissected after imaging for gamma counting, autoradiography, and histology.


 Tracer uptake was significantly higher in ApoE(-/-) mice than in both groups of control mice (1.56 ± 0.33 vs. 0.82 ± 0.24 vs. 0.98 ± 0.11, respectively; P = 0.006).  Furthermore, higher tracer activity was detected via gamma counting in the aorta of hypercholesterolemic mice than in both groups of control mice (1.52 ± 0.43 vs. 0.78 ± 0.19 vs. 0.47 ± 0.31 (99m)Tc-maraciclatide %ID/g, respectively; P = 0.018).  (99m)Tc-maraciclatide allows in vivo detection of inflamed atherosclerotic plaques in mice and may represent a non-invasive approach for identifying high-risk plaques in patients.
CT
The aorta was carefully dissected after imaging for gamma counting, autoradiography, and histology.


 Furthermore, higher tracer activity was detected via gamma counting in the aorta of hypercholesterolemic mice than in both groups of control mice (1.52 ± 0.43 vs. 0.78 ± 0.19 vs. 0.47 ± 0.31 (99m)Tc-maraciclatide %ID/g, respectively; P = 0.018). 
gamma counting
The aorta was carefully dissected after imaging for gamma counting, autoradiography, and histology.


 Autoradiography showed significantly higher tracer uptake in the atherosclerotic aorta than in the control aorta (P = 0.026). 
autoradiography