title: Accuracy of dynamic computed tomography adenosine stress myocardial perfusion imaging in estimating myocardial blood flow at various degrees of coronary artery stenosis using a porcine animal model.
abstract: OBJECTIVE
  To determine the accuracy of computed tomography (CT) dynamic stress myocardial perfusion imaging to estimate myocardial blood flow (MBF) in a porcine animal model with variable degrees of induced coronary artery stenosis in comparison with microsphere-derived MBF.
  
  
  METHODS
  Seven domestic pigs (36 ± 4 kg) received stents (confirmed 3.0 mm diameter) in the left anterior descending coronary artery distal to first diagonal branch. A balloon catheter was placed within the stent and inflated to various degrees to obtain a defined luminal narrowing (50% and 75% diameter stenosis) as confirmed by intra-arterial flow wire measurement. All models underwent adenosine-mediated (140 μg/kg/min) dynamic stress and rest myocardial perfusion CT imaging using a dual-source CT scanner (shuttle-mode with 100 kV/300 mAs, 20 mL iopromide) with prospective acquisitions every second heartbeat for 30 seconds. CT-estimated MBF (MBFCT) was calculated using a model-based parametric deconvolution method and correlated to that of fluorescent microspheres (MBFmic) injected at each perfusion state.
  
  
  RESULTS
  All study procedures were performed without complications, and all animals completed the study protocol. Among 448 myocardial segments, 31 (7%) were considered nonevaluable because of motion artifacts. With stress, MBFCT increased significantly (1.10 ± 0.25 vs. 0.80 ± 0.28 mL/g/min, P < 0.001; at stress and rest, respectively) in all myocardial segments and correlated with MBFmic (r = 0.67, P < 0.001). MBFCT overestimated MBFmic, independently of adenosine-stress and degree of coronary stenosis (β = 2.3, 95% confidence interval: 1.81-2.79 mL/g/min, P < 0.001). Although there were no differences in MBFCT between 50% and 75% coronary stenosis at rest (0.01 ± 0.08 mL/g/min, P = 0.86), MBFCT was significantly lower at 75% than at 50% under stress conditions (0.53 ± 0.19 vs. 0.71 ± 0.24 mL/g/min, P = 0.002).
  
  
  CONCLUSIONS
  CT-derived MBF measurements at rest and stress with varying degrees of coronary stenosis show a valid difference but an underestimated correlation with microsphere-derived MBF in a porcine animal model.
authors.affiliation: Department of Clinical Radiology, Ludwig-Maximilians University, Munich, Germany. fbamberg@med.lmu.de
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.forename: Rabea
authors.initials: R
authors.lastname: Hinkel
authors.forename: Florian
authors.initials: F
authors.lastname: Schwarz
authors.forename: Torleif A
authors.initials: TA
authors.lastname: Sandner
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Baloch
authors.forename: Roy
authors.initials: R
authors.lastname: Marcus
authors.forename: Alexander
authors.initials: A
authors.lastname: Becker
authors.forename: Christian
authors.initials: C
authors.lastname: Kupatt
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Wintersperger
authors.forename: Thorsten R
authors.initials: TR
authors.lastname: Johnson
authors.forename: Daniel
authors.initials: D
authors.lastname: Theisen
authors.forename: Ernst
authors.initials: E
authors.lastname: Klotz
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
mesh_terms: D000241:Adenosine; D000818:Animals; D001783:Blood Flow Velocity; D017023:Coronary Angiography / Q000379:methods*; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005080:Exercise Test; D006801:Humans; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine