title: CT attenuation correction for myocardial perfusion quantification using a PET/CT hybrid scanner.
abstract: In routine PET, a 10- to 20-min transmission scan with a rotating (68)Ge source is commonly obtained for attenuation correction (AC). AC is time-consuming using this procedure and could considerably be shortened by instead using a rapid CT scan. Our aim was to evaluate the feasibility of CT AC in quantitative myocardial perfusion PET using a hybrid PET/CT scanner.
  
  
  METHODS
  (13)N-labeled NH(3) and PET were used to measure myocardial blood flow (MBF) (mL/min/g) at rest and during standard adenosine stress. In group 1 (n = 7), CT scans (0.5 s) of the heart area with different tube currents (10, 40, 80, and 120 mA) were compared with a standard (68)Ge transmission (20 min) and with no AC. In group 2 (n = 3), the repeatability of 8 consecutive CT scans at a tube current of 10 mA was assessed. In group 3 (n = 4), emission was preceded and followed by 3 CT scans (10 mA) and 1 (68)Ge scan for each patient. For reconstruction, filtered backprojection (FBP) was compared with iterative reconstruction (IT).
  
  
  RESULTS
  For group 1, no significant difference in mean MBF for resting and hyperemic scans was found when emission reconstructed with (68)Ge AC was compared with emission reconstructed with CT AC at any of the different tube currents. Only emission without any correction differed significantly from (68)Ge AC. For group 2, repeated measurements revealed a coefficient of variance ranging from 2% to 5% and from 2% to 6% at rest and at stress, respectively. For group 3, similar reproducibility coefficients (RC) for MBF were obtained when (68)Ge AC(FBP) was compared with (68)Ge AC(IT) (RC = 0.218) and when CT AC(FBP) was compared with CT AC(IT) (RC = 0.227). Even better reproducibility (lower RC) was found when (68)Ge AC(FBP) was compared with CT AC(FBP) (RC = 0.130) and when (68)Ge AC(IT) was compared with CT AC(IT) (RC = 0.146).
  
  
  CONCLUSIONS
  Our study shows that for the assessment of qualitative and quantitative MBF with a hybrid PET/CT scanner, the use of CT AC (with a tube current of 10 mA) instead of (68)Ge AC provides accurate results.
authors.affiliation: Nuclear Cardiology, Cardiovascular Center, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Koepfli
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Hany
authors.forename: Christophe A
authors.initials: CA
authors.lastname: Wyss
authors.forename: Mehdi
authors.initials: M
authors.lastname: Namdar
authors.forename: Cyrill
authors.initials: C
authors.lastname: Burger
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Konstantinidis
authors.forename: Thomas
authors.initials: T
authors.lastname: Berthold
authors.forename: Gustav K
authors.initials: GK
authors.lastname: Von Schulthess
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Kaufmann
mesh_terms: D000465:Algorithms; D016477:Artifacts; D002138:Calibration; D017023:Coronary Angiography / Q000379:methods; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014055:Tomography, Emission-Computed / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*