A new method for Fourier analysis in ECG-gated cardiac blood pool emission computed tomography (ECT)

An integrated technique for Fourier analysis in multigated blood pool ECT study has been developed. Following the administration of 15-20 mCi of Tc-99m RBC, ECG-gated cardiac blood pool data were acquired using an ECT system with dual opposed gamma cameras. Fundamental studies for data acquisition showed that acquisition time of 10 sec. for each projection, 14 divisions of one cardiac cycle and angular interval of 6/sup 0/ (60 projections over 360/sup 0/) were reasonable for clinical purpose. Total acquisition time was about 5 minutes under these conditions. Data were processed as follows: 1) Transaxial (TA) tomographic images in every phase of cardiac cycle were reconstructed by convolution algorithm; 2) TA images were rotated to construct sagittal (SAG) and short axial (S-A) oblique-angle tomography which are respectively parallel and perpendicular to the long axis of either of the ventricles; 3) Images covering the portion other than the purposed ventricle were eliminated from the series of SAG images in every phase of the cycle; 4) Images in the same phase were summed to construct a series of SAG and S-A planar images; and 5) Fourier analysis was made to construct phase and amplitude images. The advantages of this method are that themore » phase and amplitude images from arbitrary directions can be obtained, that the region of interest can be selected on a three dimensional basis, eliminating the overlapping activity of the other ventricle or neighbouring tissues, that the diseased areas can be easily and accurately localized even in small inferior wall myocardial infarction and that patient study can be finished within 5 minutes.« less