title: CT myocardial perfusion and coronary CT angiography: Influence of coronary calcium on a stress-rest protocol.
abstract: BACKGROUND
  High amounts of coronary artery calcium limit image quality and diagnostic accuracy of multidetector computed tomography (MDCT) angiography (CTA) regarding the assessment of obstructive coronary artery disease (CAD). CT myocardial perfusion imaging may represent an opportunity to overcome this limitation.
  
  
  OBJECTIVE
  To explore the additive value of CT myocardial perfusion to CTA depending on the patient's calcium score and in comparison to the reference standard of invasive coronary angiography plus fractional flow reserve (FFR) measurement.
  
  
  METHODS
  Symptomatic patients with intermediate pretest probability of CAD were prospectively recruited and underwent both cardiac MDCT (64-slice scanner, retrospectively-gated stress-rest protocol) and invasive coronary angiography including FFR assessment. We defined hemodynamically significant CAD by the presence of occlusive or subocclusive (99%) stenosis, >50% stenosis in left main or FFR≤0.80. Stress CT myocardial perfusion imaging was performed in all patients in addition to CTA. The additive value of CT myocardial perfusion to rule in or rule out the presence of hemodynamically relevant stenosis on a per-patient basis was assessed and analyzed relative to the patient's calcium score.
  
  
  RESULTS
  95 patients were included in the analysis (62 ± 8.2 years, 68%males). Hemodynamically significant CAD was present in 42 patients. Sixty-four patients had a fully evaluable CTA examination. Per-patient, CTA alone had a sensitivity, specificity and AUC of 100%, 59% and 0.79 respectively (77% patients correctly classified). Adding CT myocardial perfusion to evaluate uninterpretable vessel territories in CTA in 66 patients with a calcium score>100 yielded a sensitivity of 88%, a specificity of 74% and an AUC of 0.81 (81% patients correctly classified), and in 52 patients with a calcium score>400 sensitivity was 91%, specificity 70%, and AUC 0.80 (82% patients correctly classified, p = 0.733 versus using perfusion imaging in all patients).
  
  
  CONCLUSIONS
  From a pragmatic standpoint, limiting the use of CT perfusion to individuals with a calcium score above 400 might be a feasible strategy to optimize the diagnostic accuracy of CT imaging for diagnosis of obstructive CAD.
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal; Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal. Electronic address: ricardoladeiraslopes@gmail.com.
authors: Ricardo
authors: R
authors: Ladeiras-Lopes
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal; Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal.
authors: Nuno
authors: N
authors: Bettencourt
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal; Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal.
authors: Nuno
authors: N
authors: Ferreira
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal; Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal.
authors: Francisco
authors: F
authors: Sampaio
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal.
authors: Gustavo
authors: G
authors: Pires-Morais
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal.
authors: Lino
authors: L
authors: Santos
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal.
authors: Bruno
authors: B
authors: Melica
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal.
authors: Alberto
authors: A
authors: Rodrigues
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal.
authors: Pedro
authors: P
authors: Braga
authors: Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal.
authors: Adelino
authors: A
authors: Leite-Moreira
authors: Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal.
authors: José
authors: J
authors: Silva-Cardoso
authors: Department of Cardiology, Gaia Hospital Centre, Vila Nova de Gaia, Portugal; Cardiovascular Research and Development Centre, Faculty of Medicine of the University of Porto, Porto, Portugal.
authors: Vasco
authors: V
authors: Gama
mesh_terms: D000368:Aged; D019540:Area Under Curve; D000072226:Computed Tomography Angiography / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D061205:Vascular Calcification / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents
keywords: Coronary artery disease; Fractional flow reserve; Multidetector computed tomography; Myocardial perfusion