title: Coronary In-Stent Restenosis: Assessment with Corrected Coronary Opacification Difference across Coronary Stents Measured with CT Angiography.
abstract: OBJECTIVE
  To determine whether changes in coronary opacification normalized to the aorta (corrected coronary opacification [CCO]) across stents can help identify in-stent restenosis (ISR) severity with use of invasive coronary angiography as the standard of reference.
  
  
  METHODS
  This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The authors retrospectively analyzed 106 patients (88 men, 18 women; mean age, 59.6 years ± 10.4; age range, 36-84 years) who had previously undergone stent implantation within 3 months of coronary computed tomographic (CT) angiography. Attenuation values in the coronary lumen were measured proximal and distal to the stents and normalized to the descending aorta. The CCO difference across the stent was compared with the severity of ISR. One-way analysis of variance least significant difference was used for comparison.
  
  
  RESULTS
  A total of 141 stents were assessed. Seventy-six stents were normally patent, 18 had ISR of less than 50%, 28 had ISR of 50%-99%, and 19 were fully occluded. The median CCO differences in the four groups were 0.078, 0.163, 0.346, and 0.606, respectively. There was no significant difference between stents with an ISR of at least 50% and those with total occlusion (P = .056), although the other groups had significant differences at pairwise comparison (P < .01 for all). For stents smaller than 3 mm in diameter, the median CCO differences in the four groups were 0.086, 0.136, 0.390, and 0.471, respectively. The CCO differences across normal stents and stents with ISR of less than 50% were significantly less than those across stents with an ISR of at least 50% and those with total occlusion (P < .01 for all). There were no significant differences between stents with no ISR and those with an ISR of less than 50% (P = .821) and between stents with an ISR of at least 50% and those with an ISR of 100% (P = .836).
  
  
  CONCLUSIONS
  The CCO difference across coronary stents is related to ISR severity in obstructive ISR in stents smaller than 3 mm in diameter.
authors.affiliation: From the Departments of Radiology (Y.G., B.L., Z.H.H., F.F.Y., W.H.Y., Z.Q.W.) and Cardiology (Y.J.W., C.W.M.), State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167 Bei-Li-Shi St, Beijing 100037, China; and Department of Radiology and Radiological Science (F.G.M., A.D.M., U.J.S.) and Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC.
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Bin
authors.initials: B
authors.lastname: Lu
authors.forename: Zhi Hui
authors.initials: ZH
authors.lastname: Hou
authors.forename: Fang Fang
authors.initials: FF
authors.lastname: Yu
authors.forename: Wei Hua
authors.initials: WH
authors.lastname: Yin
authors.forename: Zhi Qiang
authors.initials: ZQ
authors.lastname: Wang
authors.forename: Yong Jian
authors.initials: YJ
authors.lastname: Wu
authors.forename: Chao Wei
authors.initials: CW
authors.lastname: Mu
authors.forename: Felix G
authors.initials: FG
authors.lastname: Meinel
authors.forename: Andrew D
authors.initials: AD
authors.lastname: McQuiston
authors.forename: U Joseph
authors.initials: UJ
authors.lastname: Schoepf
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017023:Coronary Angiography / Q000379:methods*; D023903:Coronary Restenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015607:Stents; D014057:Tomography, X-Ray Computed