title: Optimization of non-contrast-enhanced MR angiography of the renal artery with three-dimensional balanced steady-state free-precession and time-spatial labeling inversion pulse (time-SLIP) at 3T MRI, in relation to age and blood velocity.
abstract: OBJECTIVE
  To determine the optimal inversion time (TI) value of three-dimensional (3D) balanced steady-state free-precession time-spatial labeling inversion pulse (time-SLIP) technique for visualization of the renal artery at 3T MRI, and to assess whether the optimal TI is affected by the subject's age and blood velocity.
  
  
  METHODS
  Forty-two healthy volunteers (range 20-67 years) were enrolled in the study and subjected to non-contrast-enhanced renal MR angiography. Five different TI values (1200, 1400, 1600, 1800, and 2000 ms) were selected for evaluation. For quantitative evaluation, the relative signal intensity (SI) of the main renal artery was compared with that of the renal medulla (Vessel-to-Kidney ratio; VKR). Blood velocity of the abdominal aorta was measured using 2D phase contrast technique. For qualitative evaluation, two radiologists scored the depiction of the renal pelvis and the quality of visualization of the renal artery.
  
  
  RESULTS
  VKR is the highest at TI = 1600 ms. A strong negative correlation between age and blood velocity was demonstrated. Regarding the qualitative evaluation, the overall image scores of renal arteries were the highest at a TI = 1800 ms for both readers. The optimal TI values in subjects below 50 years of age were 1600 and 1800 ms, whereas in subjects above 50 years of age, the optimal TI value was 1800 ms.
  
  
  CONCLUSIONS
  The optimal TI value for the visualization of renal arteries using time-SLIP technique at 3T MRI was 1800 ms. Subjects' age affected optimal TI and this is likely due to differences in the blood velocity of the abdominal aorta.
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Kurata
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan. akikido@kuhp.kyoto-u.ac.jp.
authors.forename: Aki
authors.initials: A
authors.lastname: Kido
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimoto
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Kiguchi
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Takakura
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Moribata
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Fuki
authors.initials: F
authors.lastname: Shitano
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Himoto
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Fushimi
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Okada
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyoku, Kyoto, 606-8507, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001783:Blood Flow Velocity; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012077:Renal Artery / Q000033:anatomy & histology*; D059629:Signal-To-Noise Ratio
keywords: Blood velocity; Non-contrast-enhanced MR angiography; Renal artery; Time-spatial labeling inversion pulse (time-SLIP)