title: T1ρmapping improvement using stretched-type adiabatic locking pulses for assessment of human liver function at 3T.
abstract: The purpose of this study is to investigate the performance of stretched-type adiabatic spin lock pulses for homogeneous spin locking with a flexible spin lock time (TSL) setting.
  
  
  
  T1ρvalues were obtained from 61 patients and five normal volunteers who were categorized using the Child-Pugh classification and scanned using each spin lock pulse type. The pulses used were the block and two kinds of hyperbolic secant (HS); HS8_10, and HS8_5. Visual scoring was categorized using a four point scale (1:Severe, 2:Moderate, 3:Mild and 4:None) to evaluate the homogeneity of the T1ρmap and the source images obtained by each spin lock pulse. Mean T1ρvalues among the patient groups with different Child-Pugh classification were compared.
  
  
  
  The visual assessment scores were 1.98 ± 1.05 for block pulse locking, 3.87 ± 0.39 for HS8_10 pulse locking, and 3.83 ± 0.45 for HS8_5 pulse locking, respectively. The scores between block pulse and HS8_10 were significantly different (p < 0.001), as were those between block pulse and HS8_5 (p < 0.001). The median T1ρvalues of normal liver function, Child-Pugh A, and Child-Pugh B or C were 37.00 ms, 40.77 ms, and 42.20 ms for block pulse, 46.75 ms, 50.78 ms, and 55.60 ms for HS8_10, and 48.80 ms, 55.42 ms, and 57.80 ms for HS8_5, respectively.
  
  
  
  The spin locking sequence using stretched-type adiabatic pulses provides homogeneous liver T1ρmaps with reduced artifact and is necessary for a robust evaluation of liver function using T1ρ.
authors.affiliation: Philips Healthcare, Tokyo, Japan; Division of Health Science, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan. Electronic address: tomoyuki.okuaki@philips.com.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Okuaki
authors.affiliation: Department of Radiology Informatics and Network, Kyushu University, Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Takayama
authors.affiliation: Department of Clinical Radiology, Kyushu University, Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nishie
authors.affiliation: Philips Electronics Japan, Tokyo, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ogino
authors.affiliation: Philips Electronics Japan, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Obara
authors.affiliation: Department of Clinical Radiology, Kyushu University, Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
authors.affiliation: Division of Health Science, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan.
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
authors.affiliation: Philips Healthcare, Tokyo, Japan.
authors.forename: Marc
authors.initials: M
authors.lastname: Van Cauteren
mesh_terms: D064368:Healthy Volunteers; D006801:Humans; D008099:Liver / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods
keywords: T(1ρ); hyperbolic secant; liver; spin lock; stretch type adiabatic pulse