Figure 21.

Noninvasive targeted imaging of matrix metalloproteinase activation in a murine model of postinfarction remodeling: hybrid micro-SPECT/CT reconstructed short-axis images were acquired without x-ray contrast (A) in a control sham-operated mouse (left) and selected mice at 1 week (middle) and 3 weeks (right) after surgical myocardial infarction (MI), after injection of ²⁰¹Tl (top row, green) and ^99mTc-RP805, (middle row, red). A black-and-white and multicolor fusion image is shown on bottom. Control heart demonstrates normal myocardial perfusion and no focal ^99mTc-RP805 uptake within the heart, although some uptake is seen in chest wall at the thoracotomy site (dashed arrows). All post-MI mice have a large anterolateral ²⁰¹Tl perfusion defect (yellow arrows) and focal uptake of ^99mTc-RP805 in defect area. A dashed circle is drawn around the heart to demonstrate localization of ^99mTc-RP805, within the infarcted area of the heart. Some activity is also seen in the peri-infarct border zone. Additional micro-SPECT/CT images were acquired by use of a higher-resolution SPECT detector after the administration of x-ray contrast, at 1 week (B) and 3 weeks (C) after MI. The contrast agent permitted better definition of the LV myocardium, which is highlighted by white dotted line. Representative short-axis (SA), horizontal long-axis (HLA), and vertical long-axis (VLA) images are shown for two additional mice by use of the same format and color scheme. Focal uptake of ^99mTc-RP805 is seen within the central infarct and peri-infarct regions, which again corresponds to ²⁰¹Tl perfusion defect. Modified, with permission, from Su H, Circulation. 2005 (364).