Abstract
1644
Objectives: Proper CT-based attenuation correction in cardiac PET/CT is limited due to respiratory motion of the heart, leading to image artifacts. These artifacts can be corrected using respiratory gating. The aim of this study was to evaluate a respiratory gating-based cardiac PET/CT protocol compared to the gold standard PET.
Methods: 16 patients underwent the following study: An ECG-triggered CT scan of the heart was performed in shallow inspiration (120 kVp, 550 mAs) on a Biograph Sensation 16 PET/CT scanner, followed by a PET list mode scan (1 h p. i. of 4 MBq/kg F-18-FDG). Gating was realized using a video camera installed at the end of the patient bed, monitoring a marker on the patient's abdomen. Gated and non-gated list mode PET data were reconstructed using end-diastolic CT data for attenuation correction. Finally, a PET scan was performed on an ECAT EXACT scanner. PET images were analyzed both visually and quantitatively (polar map analysis, 17 segment model).
Results: In three out of 16 scans, the respiration phase during the CT scan differed gravely from the average non-gated PET respiration phase resulting in artifacts in the antero-lateral left ventricular wall. Gating minimized these artifacts. Regression analysis when comparing non-gated PET/CT and PET resulted in a mean correlation coefficient of r=0.91, comparing gated PET/CT and PET resulted in r=0.92 (no significant difference). However, both mean slope and axis intercept of the regression line y=m*x+c were significantly closer to identity for gated images (m=0.94, c=0.02) than for non-gated images (m=0.88, c=0.10).
Conclusions: Non-gated cardiac PET/CT may lead to regional quantitation artifacts. Usage of PET respiratory gating results in artifact-free imaging and good accordance with stand-alone PET.
Research Support: This study was supported by the DFG (SFB 656).
- Society of Nuclear Medicine, Inc.