title: Respiratory motion detection and correction in ECG-gated SPECT: a new approach.
abstract: OBJECTIVE
  Gated myocardial perfusion single-photon emission computed tomography (GSPECT) has been established as an accurate and reproducible diagnostic and prognostic technique for the assessment of myocardial perfusion and function. Respiratory motion is among the major factors that may affect the quality of myocardial perfusion imaging (MPI) and consequently the accuracy of the examination. In this study, we have proposed a new approach for the tracking of respiratory motion and the correction of unwanted respiratory motion by the use of respiratory-cardiac gated-SPECT (RC-GSPECT). In addition, we have evaluated the use of RC-GSPECT for quantitative and visual assessment of myocardial perfusion and function.
  
  
  METHODS
  Twenty-six patients with known or suspected coronary artery disease (CAD)-underwent two-day stress and rest (99m)Tc-Tetrofosmin myocardial scintigraphy using both conventional GSPECT and RC-GSPECT methods. The respiratory signals were induced by use of a CT real-time position management (RPM) respiratory gating interface. A PIO-D144 card, which is transistor-transistor logic (TTL) compatible, was used as the input interface for simultaneous detection of both ECG and respiration signals.
  
  
  RESULTS
  A total of 26 patients with known or suspected CAD were examined in this study. Stress and rest myocardial respiratory motion in the vertical direction was 8.8-16.6 mm (mean, 12.4 +/- 2.9 mm) and 7.8-11.8 mm (mean, 9.5 +/- 1.6 mm), respectively. The percentages of tracer intensity in the inferior, inferoseptal and septal walls as well as the inferior to lateral (I/L) uptake ratio was significantly higher with the use of RC-GSPECT as compared to the use of GSPECT (p < 0.01). In a left ventricular ejection fraction (LVEF) correlation analysis between the use of rest GSPECT and RC-GSPECT with echocardiography, better correlation was noted between RC-GSPECT and echocardiography as compared with the use of GSPECT (y = 0.9654x + 1.6514; r = 0.93, p < 0.001 versus y = 0.8046x + 5.1704; r = 0.89, p < 0.001). Nineteen (19/26) patients (73.1%) showed abnormal myocardial perfusion scans with reversible regional myocardial defects; of the 19 patients, 14 (14/26) patients underwent coronary angiography.
  
  
  CONCLUSIONS
  Respiratory induced motion can be successfully corrected simultaneously with the use of ECG-gated SPECT in MPI studies using this proposed technique. Moreover, the use of ECG-gated SPECT improved image quality, especially in the inferior and septal regions that are mostly affected by diaphragmatic attenuation. However, the effect of respiratory correction depends mainly on the patient respiratory pattern and may be clinically relevant in certain cases.
authors.affiliation: Department of Medical Physics, School of Medical Sciences Tarbiat Modares University, Tehran, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Bitarafan
authors.forename: Hossein
authors.initials: H
authors.lastname: Rajabi
authors.forename: Bernhard
authors.initials: B
authors.lastname: Gruy
authors.forename: Feridoon
authors.initials: F
authors.lastname: Rustgou
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Sharafi
authors.forename: Hasan
authors.initials: H
authors.lastname: Firoozabady
authors.forename: Nahid
authors.initials: N
authors.lastname: Yaghoobi
authors.forename: Hadi
authors.initials: H
authors.lastname: Malek
authors.forename: Christian
authors.initials: C
authors.lastname: Pirich
authors.forename: Werner
authors.initials: W
authors.lastname: Langesteger
authors.forename: Mohsen
authors.initials: M
authors.lastname: Beheshti
mesh_terms: D000368:Aged; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D003326:Coronary Circulation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D012119:Respiration
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin