Abstract
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Objectives Cardiac PET image quality is affected by both cardiac and respiratory motion. Dual gating acquisition allows motion tracking but leads to excessive noise. We have modified the “Motion Frozen” (MF) processing technique (JNM 2004:45:1128-1134) to eliminate the influence of respiratory (in addition to cardiac) motion in static images and to provide fully motion-free cardiac PET imaging.
Methods Dual gated images for a patient referred for 18F-FDG myocardial viability scan were obtained using a prototype dual gating code on a Siemens Biograph-64. Static, cardiac gated (8 gates) and dual gated (8 cardiac gates, 4 amplitude-based respiratory gates) images were reconstructed using HD•PET. MF was applied to the cardiac (CMF) and dual gated (DMF) datasets. The results were end-diastolic (ED) cardiac motion-free images for CMF and end-diastolic/end-inspiration (ED/EI) fully motion-free images for DMF with no counting statistics loss. Myocardium/blood contrast and wall thickness at 3 different levels (base, mid, apex) were compared.
Results The measured myocardium/blood contrast was 4.5 in static images, 5.1 for CMF and 7.2 for DMF. The measured wall thickness averaged over 3 levels was 15.8±1.2 mm for static images, 12.7±1.2 mm for CMF and 11.7±1.0 mm for DMF. The same measurement on CTA images was 9.7±1.7 mm. DMF facilitated registration between PET and CTA since both datasets were in ED/EI phase.
Conclusions DMF cardiac PET provides fully motion-free images and leads to high quality images suitable for image registration with higher-resolution anatomical modalities.
- © 2009 by Society of Nuclear Medicine