Myocardial Infarction Area Quantification using High-Resolution SPECT Images in Rats

Abstract

BackgroundImaging techniques enable in vivo sequential assessment of the morphology and function of animal organs in experimental models. We developed a device for high-resolution single photon emission computed tomography (SPECT) imaging based on an adapted pinhole collimator. ObjectiveTo determine the accuracy of this system for quantification of myocardial infarct area in rats. MethodsThirteen male Wistar rats (250 g) underwent experimental myocardial infarction by occlusion of the left coronary artery. After 4 weeks, SPECT images were acquired 1.5 hours after intravenous injection of 555 MBq of 99mTc-Sestamibi. The tomographic reconstruction was performed by using specially developed software based on the Maximum Likelihood algorithm. The analysis of the data included the correlation between the area of perfusion defects detected by scintigraphy and extent of myocardial fibrosis assessed by histology. ResultsThe images showed a high target organ/background ratio with adequate visualization of the left ventricular walls and cavity. All animals presenting infarction areas were correctly identified by the perfusion images. There was no difference of the infarct area as measured by SPECT (21.1 ± 21.2%) and by histology (21.7 ± 22.0%; p=0.45). There was a strong correlation between individual values of the area of infarction measured by these two methods. ConclusionThe developed system presented adequate spatial resolution and high accuracy for the detection and quantification of myocardial infarction areas, consisting in a low cost and versatile option for high-resolution SPECT imaging of small rodents.

Early postnatal rat ventricle resection leads to long-term preserved cardiac function despite tissue hypoperfusion

“…; de Oliveira et al. ). Since fibrosis replaces viable muscle tissue, SPECT imaging with [ 99m Tc]Sestamibi is used clinically to estimate the infarct size, because the collagen area lacks tracer uptake (Gibbons ).…”

Cardiac Radionuclide Imaging in Rodents: A Review of Methods, Results, and Factors at Play

“…Correlation coefficients between histology-proved and SPECT-derived infarct sizes were excellent ( R 2 ranging from 0.89 to 0.98), whereas defect sizes, thresholds to define a significant uptake defect on SPECT images (range: 24–70% of the normally perfused segments), and injected activities (range: 37–555 MBq) were different between studies (22–24). …”

“…The feasibility of measuring the ischemic heart size with 99m Tc-sestamibi was tested in male Sprague-Dawley and Wistar rats by using clinical SPECT cameras, either stationary or rotating, equipped with pinhole collimators (22–24). Correlation coefficients between histology-proved and SPECT-derived infarct sizes were excellent ( R 2 ranging from 0.89 to 0.98), whereas defect sizes, thresholds to define a significant uptake defect on SPECT images (range: 24–70% of the normally perfused segments), and injected activities (range: 37–555 MBq) were different between studies (22–24).…”

Mesenchymal Stem Cells Improve Heart Rate Variability and Baroreflex Sensitivity in Rats with Chronic Heart Failure

“…Myocardial perfusion scintigraphy with 99mTc-sestamibi -SPECT Two to three days after MI, the extent of the infarcted area was determined using SPECT according to Oliveira et al [20]. Briefly, under inhaled isoflurane (Isothane; Baxter Healthcare Corporation, Guayama, Puerto Rico: 5% for induction and 1.5-2% for maintenance), the animals received a dose of 99m Tc-sestamibi (555 MBq; Piro-Tec; IPEN; Cardiolite R , Lantheus Medical Imaging) into the penile vein; after 90 min, the animals were placed in a motorized cylindrical apparatus coupled to a ''pinhole'' collimator adapted to a clinical gamma-camera (DST; SMV America).…”