In cardiac PET, CT, and MRI respiration is major reason for impaired image quality of small targets such as coronary arteries. Strong correlations between heart motion and respiratory signals have been detected but quantitative relation between signals and motion of cardiac structures in MRI or PET is not reported .

Relation between spirometric lung volume or pressure belt signal and motion of coronary vessels in MRI was studied on nine healthy volunteers. Spirometry was further applied to ¹⁸F-FDG cardiac PET study to determine quantitative relation between volume change and motion of center of myocardium activity (CMA) on nine CAD patients.

Correlation coefficients (CC) between vessel motions and volume or pressure changes were 0.90-0.92 or 0.86-0.84, respectively. The linear equations based on volume or pressure changes derived 2.0-2.6 or 2.9-3.3 mm mean estimation error for vessel motions. In PET CC value of 0.93 was determined between volume changes and CMA motions. The linear equation based on volume change derived maximum estimation error of 2.5 mm for CMA motion.

The spirometric volume change linearly estimates motion of myocardium in PET with good accuracy and have potential to guide selection of optimal number of respiratory gates in cardiac PET.