A novel technique for reduction of motion artifacts and statistical analysis between stress and rest images in ECG-gated cardiac SPECT/CT

481 Objectives SPECT/CT can correct photon attenuation favorably in cardiac perfusion SPECT, but apparent perfusion defect in apex is commonly observed as an artifact. Our phantom study revealed that this artifact resulted from greater motion in apex than other areas. To overcome this drawback of cardiac SPECT/CT and to develop a novel technique for statistical analysis, ECG-gated cardiac SPECT/CT images were spatially normalized. Methods ECG-gated SPECT/CT images of 15 patients with coronary artery diseases using 99mTc-MIBI were divided into 8 phases and reconstructed. These 8 images are spatially normalized using statistical parametric mapping with a template of a mean image. These normalized images are summed to represent each SPECT/CT image at stress and rest. Bull’s eyes of these pairs are visually inspected. Moreover, Student t-tests were applied to spatially normalized 8 paired SPECT/CT images at stress and rest. Obtained t maps were overlaid on mean images and visually interpreted. Results Spatial normalization of cardiac perfusion images diminished cardiac artifacts in apex and elevated accuracy of the interpretation of Bull’s eyes in 20% of cases. With a fixed threshold, 80% of t maps showed correct findings. Conclusions This novel technique of spatial normalization of an image at each frame of ECG-gated SPECT/CT enables us to neglect a factor of cardiac motion and to diagnose stress and rest images automatically with statistical significance.