title: Non-contrast-enhanced hepatic MR angiography with true steady-state free-precession and time spatial labeling inversion pulse: optimization of the technique and preliminary results.
abstract: OBJECTIVE
  To selectively visualize the hepatic arteries using the respiratory-triggered three-dimensional (3D) true steady-state free-precession (SSFP) projection magnetic resonance angiographic sequence with time spatial labeling inversion pulse (T-SLIP), and describe the optimization of this protocol.
  
  
  METHODS
  Twenty healthy volunteers were examined in this study. A respiratory-triggered 3D true SSFP combined with T-SLIP was performed. Among several key factors that affect the image quality, the most important is the inversion time (TI). Therefore, according to the difference in TI, four image groups: group A (TI of 800 ms), group B (TI of 1000 ms), group C (TI of 1200 ms), and group D (TI of 1400 ms), were assigned and compared to detect the optimal TI for hepatic artery visualization. For quantitative assessment, the relative signal intensity, i.e., Cv-l (vessel-to-liver contrast) of the right hepatic artery was measured. For qualitative evaluation, the quality of vessel visualization and the order of identified hepatic artery branches were evaluated by two radiologists.
  
  
  RESULTS
  Selective and high-contrast visualization of the hepatic arteries was acquired in all cases. Regarding the quantitative assessment, Cv-l decreased in group D due to background signal recovery, but there was no significant difference between groups (p-value >0.05). Regarding the qualitative evaluation, there were significant differences between group A and the other groups (p-value <0.01) and between groups B and C (p-value <0.05). In group C, both the image quality score and mean value for the order of the hepatic artery branches were highest, and a TI of 1200 ms was thought to be optimal regarding the balance between vessel-to-liver contrast and peripheral hepatic artery visualization.
  
  
  CONCLUSIONS
  The MR angiographic technique using true SSFP with T-SLIP enabled the selective visualization of hepatic arteries without the need for an exogenous contrast agent or breath-hold.
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. kotaro@kuhp.kyoto-u.ac.j
authors.forename: Kotaro
authors.initials: K
authors.lastname: Shimada
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Isoda
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Okada
authors.forename: Yoji
authors.initials: Y
authors.lastname: Maetani
authors.forename: Shigeki
authors.initials: S
authors.lastname: Arizono
authors.forename: Yuusuke
authors.initials: Y
authors.lastname: Hirokawa
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kamae
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
mesh_terms: D000328:Adult; D000465:Algorithms; D003287:Contrast Media; D005260:Female; D006499:Hepatic Artery / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D055815:Young Adult
chemical_list: D003287:Contrast Media; D013113:Spin Labels