title: Noninvasive evaluation of coronary distensibility in older adults: a feasibility study with MR angiography.
abstract: OBJECTIVE
  To assess the feasibility of using magnetic resonance (MR) angiography to noninvasively measure the coronary distensibility index (CDI) in older adults.
  
  
  METHODS
  This study was approved by the institutional review board and was compliant with HIPAA. Informed consent was obtained from all participants. Three-dimensional MR angiography was performed in 23 patients with type 2 diabetes mellitus (DM) (mean age, 72.9 years ± 5.8 [standard deviation]; age range, 65-84 years; 12 men, 11 women) and 50 healthy aging control subjects (mean age, 73.1 years ± 5.6; age range, 64-84 years; 28 men, 22 women). Imaging data were acquired in the rest periods of cardiac motion identified during end systole and middiastole. For imaging data with different acquisition windows, cross-sectional coronary planes were reconstructed and matched for the same anatomy according to coronary landmarks. The CDI, defined as [(lumen area at systole--lumen area at diastole)/(lumen area at diastole × pulse pressure)] × 1000, was compared between patients with DM and control subjects by using the Student t test. With the same protocol, CDIs were calculated in 10 randomly selected subjects by two independent readers. In addition, MR angiography (in systole and diastole) was repeated in those 10 subjects after repositioning.
  
  
  RESULTS
  CDIs were measured in 43 coronary segments of patients with DM and in 124 coronary segments of control subjects. The mean CDI in patients with DM was significantly lower than that in control subjects (2.79 mm Hg(-1) ± 2.12 vs 9.14 mm Hg(-1) ± 5.87, respectively; P < .001). CDI measurements showed good intraobserver (r = 0.914), interobserver (r = 0.820), and imaging-repeat imaging agreements (r = 0.811).
  
  
  CONCLUSIONS
  Coronary MR angiography is a reproducible and repeatable noninvasive method for detecting significant differences in coronary distensibility between patients with DM and healthy aging control subjects.
authors.affiliation: Department of Radiology, Northwestern University, 737 N Michigan Ave, Suite 1600, Chicago, IL 60611, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Lin
authors.forename: Donald M
authors.initials: DM
authors.lastname: Lloyd-Jones
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Bi
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
authors.forename: James C
authors.initials: JC
authors.lastname: Carr
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003331:Coronary Vessels / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric