title: Unenhanced MR angiography of the thoracic aorta: initial clinical evaluation.
abstract: OBJECTIVE
  In patients with difficult i.v. access or renal insufficiency, or in those who are pregnant, we hypothesized than an unenhanced 3D segmented steady-state free precession (SSFP) MR angiography (MRA) technique would be an alternative to contrast-enhanced MR angiography (CE-MRA) for the evaluation of vasculature.
  
  
  METHODS
  MRA examinations of the thoracic aorta were retrospectively reviewed in 23 patients in whom both CE-MRA and 3D SSFP were performed. CE-MRA was performed using an ECG-gated gradient-echo FLASH sequence. Three-dimensional SSFP MRA was performed during free breathing using a motion-adaptive navigator technique. Quantitative assessment of the 3D SSFP and CE-MRA image sets was performed by comparing the aortic lumen diameter. The quality of the images of the aortic root (scale of 1-5) and the presence of cardiovascular and noncardiovascular pathology were independently determined for both techniques by two reviewers. Bland-Altman and Wilcoxon's signed-rank analyses were performed.
  
  
  RESULTS
  The difference in orthogonal measurements of the aortic diameter between those made on images from the 3D SSFP and those made from the CE-MRA sequences was -0.042 cm. The aortic root was better visualized with 3D SSFP: score of 3.78 (of 5) for CE-MRA versus score of 4.65 (of 5) for 3D SSFP (p < 0.05).
  
  
  CONCLUSIONS
  In patients in whom contrast material is contraindicated, unenhanced MRA using a 3D SSFP technique can be performed.
authors: Department of Radiology, Northwestern University, Chicago, IL, USA. cfrancois@uwhealth.org
authors: Christopher J
authors: CJ
authors: François
authors: David
authors: D
authors: Tuite
authors: Vibhas
authors: V
authors: Deshpande
authors: Renate
authors: R
authors: Jerecic
authors: Peter
authors: P
authors: Weale
authors: James C
authors: JC
authors: Carr
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic; D001018:Aortic Diseases / Q000175:diagnosis*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018709:Statistics, Nonparametric