Quantitative imaging of myocardial infarct in rats with high resolution pinhole SPECT

Abstract

Small animal imaging of cardiovascular disease using single photon emission tomography (SPECT) can be used to provide quantitative measurements of myocardial infarct. The purpose of this study was to demonstrate the accuracy of pinhole SPECT imaging with [ 99m Tc]sestamibi for estimation of infarct size in a rat model of coronary artery disease. Nine rats had their left anterior descending artery ligated to induce a region of myocardial infarct. These animals were injected with 37 MBq [ 99m Tc]sestamibi, and, 1 h later, scanned on a pinhole SPECT system for 30 min. The defect size measured with SPECT, which was dependent on a threshold applied to the short axis circumferential profiles, was compared against the gold standard triphenyltetrazolium chloride (TTC) staining. The size of the perfusion deficit measured using [ 99m Tc]sestamibi SPECT compared very favorably with the TTC staining result, for threshold values in the range 50-70%. The optimum threshold was approximately 70%, giving an excellent correlation (R 2 =0.89, p<0.001). Estimation of infarct size by [ 99m Tc] sestamibi SPECT yielded an excellent agreement with TTC staining. In conclusion, measurement of myocardial infarct with SPECT can be used to study the rat heart in vivo, and provides a quantitative measure of myocardial viability.

Myocardial Perfusion Imaging is Feasible for Infarct Size Quantification in Mice Using a Clinical Single-photon Emission Computed Tomography System Equipped with Pinhole Collimators

“…The optimal intensity threshold for differentiating infarcted and non-infarcted left ventricular myocardium was found by performing linear regression analyses, as described previously [5]. Briefly, linear regression lines plots of calculated infarct size as a function of measured infarct size were calculated for a range of possible threshold values.…”

“…With such a SPECT system, Acton et al recently demonstrated accurate quantification of infarct sizes in rats, as compared to the gold standard histological staining with triphenyltetrazolium chloride [5]. Compared to rat models, murine models present a number of advantages, including low cost, and the availability of an enormous number of knockout models.…”

Comparison of Reconstruction Methods in a Small Animal Cardiac Positron Emission Tomography Study Using a 18F-Labeled Myocardial Agent, [18F] FPTP

“…Normal rats were imaged using dedicated microPET (Inveon following the described method (13). In brief, activated 18 F fluoride was added to 4.0 mg of pentane-1, 5-diyl bis (4-methylbenzenesulfonate) dissolved in acetonitrile. The reaction mixture was heated for 5 minutes at 90°C.…”

Evaluation of a Mitochondrial Voltage Sensor, (18F-Fluoropentyl)Triphenylphosphonium Cation, in a Rat Myocardial Infarction Model

“…We compared the defect size on small-animal PET images with the gold standard 2,3,5-triphenyltetrazolium chloride (TTC)-stained images (32,33). In the presence of dehydrogenase enzyme that exists in viable myocardium, TTC is reduced and forms a formazan precipitate that makes viable tissue turn brick-red, whereas nonviable infarcted tissue without dehydrogenase activity remains pale.…”