Evaluation of the wall motion abnormality using ECG-gated cardiac pool emission CT in patients of myocardial infarction

The purpose of this study is to evaluate the usefulness of ECG-gated cardiac pool emission CT (pool-ECT) compared with the conventional first pass (FP) and equilibrium (EQ) methods in evaluating wall motion abnormality (WMA). Five normal volunteers and 14 patients with myocardial infarction were studied. Following the administration of vivo-labeled sup(99m)Tc-RBC 40 mCi, the pool-ECT method was performed by rotating the gamma camera 1800 around the patient at a rate of 50/30 sec, then sagittal, coronal and 4-chamber view tomographic images were reconstructed. Moreover the amplitude and phase images were derived from first harmonic Fourier analysis and the pool-ECT data was compared with the FP and EQ data in respect to wall motion, amplitude and phase delay. The sensitivity regarding WMA was improved in 12 (55 %) of all 22 WMA by pool-ECT. Conventional and pool-ECT methods could detect the diminished amplitude activity in 16 (73 %) and in 19 (86 %) of all 22 infarct site respectively, and could detect the phase delay in 16 (73 %) and in 20 (91 %) of all 22 infarct site respectively. The pool-ECT method was more sensitive to detect WMA, especially inferior WMA which was inaccurately estimated by FP method. The advantages of this method was that the overlapping of each cardiac chamber could be ignored, that the wall motion could be evaluated by three dimensional tomographic images and that it could demonstrate small WMA which could not be detected by conventional methods. (author)