title: Assessment of thoracic aortic dimensions in an experimental setting: comparison of different unenhanced magnetic resonance angiography techniques with electrocardiogram-gated computed tomography angiography for possible application in the pediatric population.
abstract: OBJECTIVE
  To compare different unenhanced magnetic resonance angiography (MRA) techniques for quantitative evaluation of vessel lumen in an experimental setting in young pigs whose dimensions allow for a comparison with a pediatric population.
  
  
  METHODS
  Magnetic resonance imaging was performed in 5 healthy ventilated pigs at 1.5 T. Three different electrocardiogram (ECG)-triggered sequences were applied for MRA: [TSE-Db] T2-weighted dark-blood TurboSpinEcho (2.0 x 1.1 x 4 mm3); [trueFISP] 2D-steady-state-free-precession (2.2 x 1.8 x 2 mm3); [NAV] respiratory-gated, T2-prepared 3D-trueFISP (1.3 x 1.3 x 1.3 mm3). ECG-gated-CT angiography (CTA) (16-row CT, 1 mm collimation) served as the standard of reference. The vessel lumen was measured at 7 positions perpendicularly angulated to the vessel wall on multiplanar reformations: ascending aorta (P1), the aortic arch before (P2) and after (P3) the origin of the first supraaortic branch, the aortic arch after the origin of the second supraaortic branch (P4), the descending aorta at the level of the diaphragm (P5), and the first and second supraaortic branches (P6, P7).
  
  
  RESULTS
  Percentage differences in the vessel area determined by MRA reformation compared with CTA-reformation were 10% +/- 20% and 35% +/- 27% (TSE-Db), -4% +/- 13% and 20% +/- 24% (trueFISP), and -3% +/- 13% and -10% +/- 19% (NAV), for positions P1 to P5 and P6 to P7, respectively. A significant difference from CTA was found for TSE-Db at all positions, and for trueFISP only at positions P6 and P7.
  
  
  CONCLUSIONS
  Unenhanced MRA techniques allow for a reliable assessment of the dimensions of the thoracic aorta compared with CTA as the standard of reference. Using ECG-gating and navigator techniques, the free-breathing approach showed the best agreement with CTA. This technique may therefore be the most useful in the pediatric age group allowing for true 3D data acquisition with its inherent postprocessing possibilities.
authors.affiliation: Department of Radiology (E010), German Cancer Research Center, Heidelberg, Germany. juliazapo@web.de
authors.forename: Julia
authors.initials: J
authors.lastname: Ley-Zaporozhan
authors.forename: Karl-Friedrich
authors.initials: KF
authors.lastname: Kreitner
authors.forename: Roland
authors.initials: R
authors.lastname: Unterhinninghofen
authors.forename: Emma
authors.initials: E
authors.lastname: Helm
authors.forename: Michael
authors.initials: M
authors.lastname: Puderbach
authors.forename: Jens-Peter
authors.initials: JP
authors.lastname: Schenk
authors.forename: Vibhas
authors.initials: V
authors.lastname: Deshpande
authors.forename: Frank
authors.initials: F
authors.lastname: Krummenauer
authors.forename: Gabor
authors.initials: G
authors.lastname: Szabo
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ley
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D002648:Child; D003287:Contrast Media; D004562:Electrocardiography / Q000379:methods; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media