title: Absolute quantification of myocardial blood flow with 13N-ammonia and 3-dimensional PET.
abstract: The aim of this study was to compare 2-dimensional (2D) and 3-dimensional (3D) dynamic PET for the absolute quantification of myocardial blood flow (MBF) with (13)N-ammonia ((13)N-NH(3)).
  
  
  METHODS
  2D and 3D MBF measurements were collected from 21 patients undergoing cardiac evaluation at rest (n = 14) and during standard adenosine stress (n = 7). A lutetium yttrium oxyorthosilicate-based PET/CT system with retractable septa, enabling the sequential acquisition of 2D and 3D images within the same patient and study, was used. All 2D studies were performed by injecting 700-900 MBq of (13)N-NH(3). For 14 patients, 3D studies were performed with the same injected (13)N-NH(3) dose as that used in 2D studies. For the remaining 7 patients, 3D images were acquired with a lower dose of (13)N-NH(3), that is, 500 MBq. 2D images reconstructed by use of filtered backprojection (FBP) provided the reference standard for MBF measurements. 3D images were reconstructed by use of Fourier rebinning (FORE) with FBP (FORE-FBP), FORE with ordered-subsets expectation maximization (FORE-OSEM), and a reprojection algorithm (RP).
  
  
  RESULTS
  Global MBF measurements derived from 3D PET with FORE-FBP (r = 0.97), FORE-OSEM (r = 0.97), and RP (r = 0.97) were well correlated with those derived from 2D FBP (all Ps < 0.0001). The mean +/- SD differences in global MBF measurements between 3D FORE-FBP and 2D FBP and between 3D FORE-OSEM and 2D FBP were 0.01 +/- 0.14 and 0.01 +/- 0.15 mL/min/g, respectively. The mean +/- SD difference in global MBF measurements between 3D RP and 2D FBP was 0.00 +/- 0.16 mL/min/g. The best correlation between 2D PET and 3D PET performed with the lower injected activity was found for the 3D FORE-FBP reconstruction algorithm (r = 0.95, P < 0.001).
  
  
  CONCLUSIONS
  For this scanner type, quantitative measurements of MBF with 3D PET and (13)N-NH(3) were in excellent agreement with those obtained with the 2D technique, even when a lower activity was injected.
authors.affiliation: Clinic of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Tiziano
authors.initials: T
authors.lastname: Schepis
authors.forename: Oliver
authors.initials: O
authors.lastname: Gaemperli
authors.forename: Valerie
authors.initials: V
authors.lastname: Treyer
authors.forename: Ines
authors.initials: I
authors.lastname: Valenta
authors.forename: Cyrill
authors.initials: C
authors.lastname: Burger
authors.forename: Pascal
authors.initials: P
authors.lastname: Koepfli
authors.forename: Mehdi
authors.initials: M
authors.lastname: Namdar
authors.forename: Itaru
authors.initials: I
authors.lastname: Adachi
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Kaufmann
mesh_terms: D000368:Aged; D000641:Ammonia; D003326:Coronary Circulation; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009590:Nitrogen Radioisotopes; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals
chemical_list: D009590:Nitrogen Radioisotopes; D019275:Radiopharmaceuticals; D000641:Ammonia