Quantitation of regional ejection fractions using gated tomographic imaging with 99mTc-sestamibi

Gated single photon emission CT (SPECT) sestamibi imaging allows the simultaneous assessment of myocardial perfusion and left ventricular function.

The purpose of this study was to evaluate a technique for quantitative regional wall motion assessment using gated SPECT (99m)Tc-sestamibi imaging.

Fourteen subjects without cardiac pathology and 25 patients who had experienced myocardial infarction (MI) were studied. After tomographic reconstruction of gated short-axis slices, the identification of endocardial borders was made using a standard edge-detection program in systole and diastole in each of five selected slices. Regional ejection fraction (EF) and myocardial perfusion were determined for five regions within each slice. Ten patients underwent echocardiographic regional wall-motion analysis, the results of which were compared to corresponding regional EF results.

High interobserver reproducibility in the assessment of regional EFs was found, with r values ranging from 0.94 to 0.98. In patients with anterior and inferior MIs, the regional EFs were abnormal in the anterior and septal regions, and the inferior and lateral regions, respectively. The regional EFs correlated significantly with regional perfusion in the anterior walls (r = 0.71; p = 0.0001), the lateral walls (r = 0.66; p = 0.0001), and inferior walls (r = 0.54; p = 0.0004). There was a significant association between the regional EFs and the echocardiographic regional wall motion assessment at the base (p < 0.0001), mid-ventricle (p = 0.0004), and apex (p = 0.0003).

Gated SPECT images obtained (99m)Tc-sestamibi can provide reproducible quantitative, segmental regional EFs for multiple left ventricular slices that are significantly associated with subjective regional wall motion assessment by echocardiography.