Clinical validation of automatic quantitative defect size in rest technetium-99m-sestamibi myocardial perfusion SPECT.

Abstract

We examined the relationships of automatic quantitative perfusion defect size and defect severity to rest left ventricular ejection fraction and semiquantitative visual sestamibi defect size in rest 99mTc-sestamibi SPECT in 40 consecutive patients with a history of myocardial infarction more than 30 days prior to testing. The purpose of this investigation was to validate the use of automatic quantitative rest sestamibi SPECT as a clinical measure of assessing relative infarction size. All patients received 20-30 mCi of 99mTc-sestamibi followed by SPECT imaging. Quantitative defect analysis used previously developed resting normal limits and an automatic version of a commercially available quantitative program (CEqual). Semiquantitative visual defect interpretation used a 20 segment/scan and five-point scoring analysis. First-pass (FP) radionuclide ventriculography (RVG) and gated sestamibi perfusion SPECT were each performed in 31 patients. LVEF assessed by FP RVG was 37% +/- 15% (range 14%-62%) and 37% +/- 16% (range 12%-63%) by gated perfusion SPECT with high linear correlation (r = 0.96, n = 22) between the two methods. Myocardial perfusion defect size was 24% +/- 15% of LV (range 0%-50%) and defect severity was 1103 +/- 864 (range 0 to 2825) by automatic quantitative rest sestamibi. Perfusion defect size and defect severity both had close correlations with LVEF by FP RVG (r = -0.78, r = -0.86) and by gated perfusion SPECT (r = -0.75, r = -0.79). High linear correlations were observed between quantitative defect size and summed visual score of segments with score > or = 2 (r = 0.82) and the number of visually abnormal segments (r = 0.77), as well as between defect severity and visual summed rest score (r = 0.86) and the number of visually abnormal segments (r = 0.76). Quantitation of rest sestamibi SPECT defect extent and severity using automatic CEqual correlates well with rest LVEF and with semiquantitative expert visual analysis. Results of this study define a strong relationship between measurements of 99mTc-sestamibi perfusion defect as measured by an automatic software program and global left ventricular function. The automatic quantitative program appears to be a useful measure of assessing infarct size in patients with remote myocardial infarction.