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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

Ley-Zaporozhan, Julia MD*†; Kreitner, Karl-Friedrich MD; Unterhinninghofen, Roland M.eng§¶; Helm, Emma MD; Puderbach, Michael MD*; Schenk, Jens-Peter MD; Deshpande, Vibhas PhD**; Krummenauer, Frank PhD; Szabo, Gabor MD§; Kauczor, Hans-Ulrich MD*; Ley, Sebastian MD*†

doi: 10.1097/RLI.0b013e31815f8870
Original Article

Purpose: 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.

Material and 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 × 1.1 × 4 mm3); [trueFISP] 2D-steady-state-free-precession (2.2 × 1.8 × 2 mm3); [NAV] respiratory-gated, T2-prepared 3D-trueFISP (1.3 × 1.3 × 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.

From the *Department of Radiology (E010), German Cancer Research Center, Heidelberg, Germany; †Department of Pediatric Radiology, Ruprecht-Karls University, Heidelberg, Germany; ‡Department of Diagnostic and Interventional Radiology, Johannes Gutenberg University, Mainz, Germany; §Department of Cardiac Surgery, Ruprecht-Karls University, Heidelberg, Germany; ¶Department of Computer Science, University of Karlsruhe, Germany; ∥Department of Radiology, Bristol Royal Infirmary, Bristol, UK; **Cardiovascular Center, Siemens Medical Solutions, Los Angeles, CA; and ††Clinical Epidemiology and Health Economy Unit, Carl Gustav Carus University Hospital, Dresden, Germany.

Received May 9, 2007, and accepted for publication, after revision, October 1, 2007.

Reprints: Julia Ley-Zaporozhan, MD, Department of Pediatric Radiology, Ruprecht-Karls University, Heidelberg, Germany. E-mail:

© 2008 Lippincott Williams & Wilkins, Inc.