title: Aortic Volumetry at Contrast-Enhanced Magnetic Resonance Angiography: Feasibility as a Sensitive Method for Monitoring Bicuspid Aortic Valve Aortopathy.
abstract: Bicuspid aortic valve patients can develop thoracic aortic aneurysms and therefore require serial imaging to monitor aortic growth. This study investigates the reliability of contrast-enhanced magnetic resonance angiography (CEMRA) volumetry compared with 2-dimensional diameter measurements to identify thoracic aortic aneurysm growth.
  
  
  
  A retrospective, institutional review board-approved, and Health Insurance Portability and Accountability Act-compliant study was conducted on 20 bicuspid aortic valve patients (45 ± 8.9 years, 20% women) who underwent serial CEMRA with a minimum imaging follow-up of 11 months. Magnetic resonance imaging was performed at 1.5 T with electrocardiogram-gated, time-resolved CEMRA. Independent observers measured the diameter at the sinuses of Valsalva (SOVs) and mid ascending aorta (MAA) as well as ascending aorta volume between the aortic valve annulus and innominate branch. Intraobserver/interobserver coefficient of variation (COV) and intraclass correlation coefficient (ICC) were computed to assess reliability. Growth rates were calculated and assessed by Student t test (P < 0.05, significant). The diameter of maximal growth (DMG), defined as the diameter at SOV or MAA with the faster growth rate, was recorded.
  
  
  
  The mean time of follow-up was 2.6 ± 0.82 years. The intraobserver COV was 0.01 for SOV, 0.02 for MAA, and 0.02 for volume (interobserver COV: 0.02, 0.03, 0.04, respectively). The ICC was 0.83 for SOV, 0.86 for MAA, 0.90 for DMG, and 0.95 for volume. Average aortic measurements at baseline and (follow-up) were 42 ± 3 mm (42 ± 3 mm, P = 0.11) at SOV, 46 ± 4 mm (47 ± 4 mm, P < 0.05) at MAA, and 130 ± 23 mL (144 ± 24 mL, P < 0.05). Average size changes were 0.2 ± 0.6 mm/y (1% ± 2%) at SOV, 0.5 ± 0.8 mm/y (1% ± 2%) at MAA, 0.7 ± 0.7 mm/y (2% ± 2%) at DMG, and 6 ± 3 mL/y (4% ± 3%) with volumetry.
  
  
  
  Three-dimensional CEMRA volumetry exhibited a larger effect when examining percentage growth, a better ICC, and a marginally lower COV. Volumetry may be more sensitive to growth and possibly less affected by error than diameter measurements.
authors.affiliation: From the *Feinberg School of Medicine, Northwestern University, Chicago, IL; †Department of Radiology, UCLA Medical Center, Los Angeles, CA; and ‡Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Brian
authors.initials: B
authors.lastname: Trinh
authors.forename: Iram
authors.initials: I
authors.lastname: Dubin
authors.forename: Ozair
authors.initials: O
authors.lastname: Rahman
authors.forename: Marcos P
authors.initials: MP
authors.lastname: Ferreira Botelho
authors.forename: Nicholas
authors.initials: N
authors.lastname: Naro
authors.forename: James C
authors.initials: JC
authors.lastname: Carr
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Collins
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Barker
mesh_terms: D017545:Aortic Aneurysm, Thoracic / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D001021:Aortic Valve / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology; D000082882:Bicuspid Aortic Valve Disease; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000150:complications* / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media