Dual cardiac–respiratory gated PET: implementation and results from a feasibility study
- 426 Downloads
Spatial resolution in myocardial imaging is impaired by both cardiac and respiratory motion owing to motional blurring. We investigated the feasibility of a dual cardiac–respiratory gated positron emission tomography (PET) acquisition using a clinical PET/computer tomography (CT) scanner. We describe its implementation and present results on the respiratory motion observed.
The correlation between diaphragmatic excursion measured by real-time magnetic resonance imaging (MRI) and the expansion of the chest measured with an elastic belt was studied in six subjects. PET list mode acquisitions were then performed in 12 patients, six of them injected with 13N-ammonia and six with 18F-FDG. In parallel, the ECG and respiratory signals of the patients were recorded and the list mode file correspondingly sorted using a dual gated approach. Respiratory motion of the heart was quantified by measuring the displacement between the inspiratory and expiratory images in the diastolic phase by means of intensity-based non-rigid image registration.
The correlation between diaphragmatic excursion and expansion of the chest was excellent (R 2 = 0.91), validating the ability of the elastic belt to provide an adequate respiratory trigger. Respiratory signals corresponding to the chest expansion showed a large inter-patient variability, requiring adapted algorithms in order to define suitable respiratory gates. Dual gated PET series were successfully acquired for both groups of patients, showing better resolved myocardial walls. The average respiratory motion of the heart measured by PET was 4.8 mm, with its largest component in the craniocaudal direction. Moreover, a deformation of the heart with respiration was observed, with the inferior wall moving significantly more than the anterior.
Dual gated cardiac PET studies were performed successfully and showed better resolved myocardial walls as compared with ungated acquisitions. The respiratory motion of the heart presented a significant elastic component and was of the same magnitude as the spatial resolution of current PET cameras.
KeywordsPET Cardiology Respiratory gating Registration
This project was supported in part by a research grant from Siemens Medical Solutions, Chicago (IL).
- 5.Brambilla M, Secco C, Dominietto M, Matheoud R, Sacchetti G, Inglese E. Performance characteristics obtained for a new 3-dimensional lutetium oxyorthosilicate-based whole-body PET/CT scanner with the National Electrical Manufacturers Association NU 2-2001 Standard. J Nucl Med 2005;46:2083–91.PubMedGoogle Scholar
- 13.Danias PG, Stuber M, Botnar RM, Kissinger KV, Edelman RR, Manning WJ. Relationship between motion of coronary arteries and diaphragm during free breathing: lessons from real-time MR imaging. Am J Roentgenol 1999;172:1061–5.Google Scholar
- 18.Martinez-Möller A, Souvatzoglou M, Navab N, Schwaiger M, Nekolla SG. Artifacts from misaligned CT in cardiac perfusion PET/CT studies: frequency, effects and potential solutions. J Nucl Med 2007;2:188–93.Google Scholar
- 19.Modersitzki J. Numerical methods for image registration. Oxford; Oxford University Press; 2004.Google Scholar
- 20.Briggs WL, Henson VE, MacCormick SF. A multigrid tutorial. Philadelphia, PA; Society for Industrial and Applied Mathematics; 2000.Google Scholar
- 25.Manke D, Nehrke K, Rosch P, Bornert P, Dossel O. Study of respiratory motion in coronary MRA. Proc. 9th Annu. Meeting ISMRM, Glasgow, UK, 2001, no. 1852.Google Scholar