Assessment of small-animal cardiac data acquired using SPECT requires an accurate understanding of the reproducibility and the uncertainties associated with the technique. Furthermore, it is also useful to have a baseline of reference data against which to compare the outcome of a particular study.
Methods: We scanned both healthy and post-myocardial infarction rats injected with (99m)Tc-tetrofosmin in a multidetector, multipinhole small-animal SPECT scanner. In this paper, we report on the creation of a reference database of the relative myocardial blood perfusion of rats. We also evaluated the reproducibility of perfusion measurements and measurements of left ventricle volume and ejection fraction, defined as the SD of a particular measurement repeated on the same animal or over multiple animals.
Results: For the healthy rats, interscan reproducibility of volume measurements was 4%-7% of the total volume, and intersubject reproducibility was 9%-12% of the volume being measured. Interscan reproducibility remained unaffected after infarction (6%-8%), but intersubject reproducibility was much poorer (15%-26%). Ejection fraction in healthy animals was highly reproducible between scans and between rats: 3.1% and 3.3%, respectively. Interscan reproducibility of the postinfarction ejection fraction was 3.6%; intersubject reproducibility after infarction was 8.1%.
Conclusion: We have created a reference database for small-animal SPECT perfusion measurements in healthy male Sprague-Dawley rats and quantified the reproducibility of perfusion and functional measurement made with small-animal SPECT in healthy and postinfarction rats.