title: Effect of patient positioning on the evaluation of myocardial perfusion SPECT.
abstract: ECG-gated SPECT myocardial perfusion imaging is usually acquired in supine position. However, some patients are not comfortable in this position for a variety of personal or medical reasons. Our aim was to investigate the effect of patient positioning on quantitative SPECT imaging results using normal supine database.
  
  
  
  55 patients (mean age 58.5 ± 8.3 years) were enrolled in this prospective study. Each patient had a pair of ECG-gated stress SPECT myocardial perfusion images acquired on two gamma cameras: one in supine position and the other in upright sitting position. Left ventricular (LV) ejection fraction (EF), end-diastolic (ED), and end-systolic (ES) left ventricular volumes (V), LV mass, summed stress perfusion defect score (SSS), and total severity score (TSS) were calculated automatically relative to a supine normal reference database.
  
  
  
  There were no significant differences in LVEF using the two cameras (0.65 ± 0.08 vs. 0.66 ± 0.10; P > 0.1). However, EDV, ESV, and LV mass were significantly smaller in sitting position than in supine position (89 vs. 80 ml; 33 vs. 29 ml and 115 vs. 109 ml, respectively, all P < 0.0001). On the other hand, SSS and TSS were significantly higher in sitting position than in supine position (5.16 vs. 8.73 and 166.82 vs. 288.27, both P < 0.0001). Overall, more studies in sitting position were interpreted as abnormal than in supine position (P < 0.05).
  
  
  
  Patient positioning has a significant impact on quantitative gated SPECT imaging results. Using a supine normal reference database, SSS and TSS were larger in sitting position than in supine position. Thus, for imaging in sitting position, separate normal limits are required.
authors.affiliation: Institute of Cardiology, University of Debrecen, Móricz Zs. krt. 22., Debrecen, 4032, Hungary. kracsko.bertalan@med.unideb.hu.
authors.forename: Bertalan
authors.initials: B
authors.lastname: Kracskó
authors.affiliation: ScanoMed Ltd., Debrecen, Hungary.
authors.forename: Sándor
authors.initials: S
authors.lastname: Barna
authors.affiliation: ScanoMed Ltd., Debrecen, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Sántha
authors.affiliation: ScanoMed Ltd., Debrecen, Hungary.
authors.forename: Anett
authors.initials: A
authors.lastname: Kiss
authors.affiliation: Department of Nuclear Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Varga
authors.affiliation: ScanoMed Ltd., Debrecen, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Forgács
authors.affiliation: ScanoMed Ltd., Debrecen, Hungary.
authors.forename: Ildikó
authors.initials: I
authors.lastname: Garai
mesh_terms: D000368:Aged; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography / Q000379:methods*; D003326:Coronary Circulation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D056888:Patient Positioning; D011446:Prospective Studies; D016277:Ventricular Function, Left
keywords: ECG-gated SPECT; Myocardial perfusion imaging; patient positioning; sitting vs. supine position