title: Comparison of nonenhanced MR angiographic subtraction techniques for infragenual arteries at 1.5 T: a preliminary study.
abstract: OBJECTIVE
  To evaluate diagnostic performance of three nonenhanced methods: variable-refocusing-flip angle (FA) fast spin-echo (SE)-based magnetic resonance (MR) angiography (variable FA MR) and constant-refocusing-FA fast SE-based MR angiography (constant-FA MR) and flow-sensitive dephasing (FSD)-prepared steady-state free precession MR angiography (FSD MR) for calf arteries, with dual-injection three-station contrast material-enhanced MR angiography (gadolinium-enhanced MR) as reference.
  
  
  METHODS
  This prospective study was institutional review board approved and HIPAA compliant, with informed consent. Twenty-one patients (13 men, eight women; mean age, 62.6 years) underwent calf-station variable-FA MR, constant-FA MR, and FSD MR at 1.5 T, with gadolinium-enhanced MR as reference. Image quality and stenosis severity were assessed in 13 segments per leg by two radiologists blinded to clinical data. Combined constant-FA MR and FSD MR reading was also performed. Methods were compared (logistic regression for correlated data) for diagnostic accuracy.
  
  
  RESULTS
  Of 546 arterial segments, 148 (27.1%) had a hemodynamically significant (≥ 50%) stenosis. Image quality was satisfactory for all nonenhanced MR sequences. FSD MR was significantly superior to both other sequences (P < .0001), with 5-cm smaller field of view; 9.6% variable-FA MR, 9.6% constant-FA MR, and 0% FSD MR segmental evaluations had nondiagnostic image quality scores, mainly from high diastolic flow (variable-FA MR) and motion artifact (constant-FA MR). Stenosis sensitivity and specificity were highest for FSD MR (80.3% and 81.7%, respectively), compared with those for constant-FA MR (72.3%, P = .086; and 81.8%, P = .96) and variable-FA MR (75.9%, P = .54; and 75.6%, P = .22). Combined constant-FA MR and FSD MR had superior sensitivity (81.8%) and specificity (88.3%) compared with constant-FA MR (P = .0076), variable-FA MR (P = .0044), and FSD MR (P = .0013). All sequences had an excellent negative predictive value (NPV): 93.2%, constant-FA MR; 94.7%, variable-FA MR; 91.7%, FSD MR; and 92.9%, combined constant-FA MR and FSD MR.
  
  
  CONCLUSIONS
  At 1.5 T, all evaluated nonenhanced MR angiographic methods demonstrated satisfactory image quality and excellent NPV for hemodynamically significant stenosis.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120859/-/DC1.
authors.affiliation: Department of Radiology, New York University Medical Center, New York, NY, USA. ruth.lim@austin.org.au
authors.forename: Ruth P
authors.initials: RP
authors.lastname: Lim
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Fan
authors.forename: Manjil
authors.initials: M
authors.lastname: Chatterji
authors.forename: Amanjit
authors.initials: A
authors.lastname: Baadh
authors.forename: Iliyana P
authors.initials: IP
authors.lastname: Atanasova
authors.forename: Pippa
authors.initials: P
authors.lastname: Storey
authors.forename: Danny C
authors.initials: DC
authors.lastname: Kim
authors.forename: Sooah
authors.initials: S
authors.lastname: Kim
authors.forename: Philip A
authors.initials: PA
authors.lastname: Hodnett
authors.forename: Afhsan
authors.initials: A
authors.lastname: Ahmad
authors.forename: David R
authors.initials: DR
authors.lastname: Stoffel
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Mark A
authors.initials: MA
authors.lastname: Adelman
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007866:Leg / Q000098:blood supply*; D016015:Logistic Models; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA