Abstract
Inflammation that occurs following acute myocardial infarction plays a pivotal role in "healing" by facilitating the creation of a supportive scar. 18F-FDG, which is taken up avidly by macrophages, has been proposed as a marker of cell-based inflammation. However, its reliability as an accurate indicator of inflammation has not been established, particularly in the early post infarction period when regional myocardial perfusion is often severely compromised. Methods: Nine adult dogs underwent left anterior descending coronary occlusion with or without reperfusion. Animals were imaged between 7 to 21 days post infarction with Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) following: a) bolus injection of Gd-DTPA, b) bolus injection of 18F-FDG, c) bolus injection of 99Tc-DTPA to simulate the distribution of Gd-DTPA (which represents its partition coefficient in well perfused tissue) and d) the injection of 111Indium-labeled white blood cells 24 hours earlier. Following sacrifice, myocardial tissue concentrations of 18F, 111In and 99Tc were determined in a well counter. Linear regression analysis evaluated the relationships between a) the concentrations of 111In vs 18F and b) the dependence of the ratio of 111In/18F to the apparent distribution volume of 99mTc-DTPA. Results: In seven of the nine animals 111In increased as 18F increased with the other two animals showing weak negative slopes. With respect to the dependence of 111In/18F with partition coefficient four animals showed no dependence and four showed a week positive slope with one animal showing a negative slope. Further, in regions of extensive microvascular obstruction, 18F significantly underestimated the extent of the presence of 111In. Conclusion: In the early post myocardial infarction period, PET 18F-FDG imaging following a single bolus administration may underestimate the extent and degree of inflammation within regions of microvascular obstruction.
- Cardiology (basic/technical)
- Molecular Imaging
- PET/MRI
- 18FDG
- Left ventricular remodelling
- Myocardial infarction
- Myocardial inflammation
- PET/MRI
- Copyright © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.