title: Noninvasive diagnosis of ischemia-causing coronary stenosis using CT angiography: diagnostic value of transluminal attenuation gradient and fractional flow reserve computed from coronary CT angiography compared to invasively measured fractional flow reserve.
abstract: OBJECTIVE
  The aim of this study was to compare the diagnostic performance of coronary computed tomography angiography (CCTA)-derived computed fractional flow reserve (FFR(CT)) and transluminal attenuation gradient (TAG) for the diagnosis of lesion-specific ischemia.
  
  
  BACKGROUND
  Although CCTA is commonly used to detect coronary artery disease (CAD), it cannot reliably assess the functional significance of CAD. Novel technologies based on CCTA were developed to integrate anatomical and functional assessment of CAD; however, the diagnostic performance of these methods has never been compared.
  
  
  METHODS
  Fifty-three consecutive patients who underwent CCTA and coronary angiography with FFR measurement were included. Independent core laboratories determined CAD severity by CCTA, TAG, and FFR(CT). The TAG was defined as the linear regression coefficient between intraluminal radiological attenuation and length from the ostium; FFR(CT) was computed from CCTA data using computational fluid dynamics technology.
  
  
  RESULTS
  Among 82 vessels, 32 lesions (39%) had ischemia by invasive FFR (FFR ≤0.80). Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratio of TAG (≤ -0.654 HU/mm) for detection of ischemia were 38%, 88%, 67%, 69%, 3.13, and 0.71, respectively; and those of FFR(CT) were 81%, 94%, 90%, 89%, 13.54, and 0.20, respectively. Receiver-operating characteristic curve analysis showed a significantly larger area under the curve (AUC) for FFR(CT) (0.94) compared to that for TAG (0.63, p < 0.001) and CCTA stenosis (0.73, p < 0.001). In vessels with noncalcified plaque or partially calcified plaque, FFR(CT) showed a larger AUC (0.94) compared to that of TAG (0.63, p < 0.001) or CCTA stenosis (0.70, p < 0.001). In vessels with calcified plaque, AUC of FFR(CT) (0.92) was not statistically larger than that of TAG (0.75, p = 0.168) or CCTA stenosis (0.80, p = 0.195).
  
  
  CONCLUSIONS
  Noninvasive FFR computed from CCTA provides better diagnostic performance for the diagnosis of lesion-specific ischemia compared to CCTA stenosis and TAG.
authors.affiliation: Department of Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Yeonyee E
authors.initials: YE
authors.lastname: Yoon
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Choi
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Kyung-Woo
authors.initials: KW
authors.lastname: Park
authors.forename: Joon-Hyung
authors.initials: JH
authors.lastname: Doh
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
authors.forename: James K
authors.initials: JK
authors.lastname: Min
authors.forename: Andrejs
authors.initials: A
authors.lastname: Erglis
authors.forename: Hyeon-Cheol
authors.initials: HC
authors.lastname: Gwon
authors.forename: Yeon Hyeon
authors.initials: YH
authors.lastname: Choe
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Choi
authors.forename: Hyo-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Byung-Hee
authors.initials: BH
authors.lastname: Oh
authors.forename: Young-Bae
authors.initials: YB
authors.lastname: Park
mesh_terms: D000368:Aged; D019540:Area Under Curve; D006328:Cardiac Catheterization; D017023:Coronary Angiography / Q000379:methods*; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D061330:Multidetector Computed Tomography; D058226:Plaque, Atherosclerotic; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012042:Registries; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D061205:Vascular Calcification / Q000000981:diagnostic imaging / Q000503:physiopathology