title: Image quality and focal lesion detection on T2-weighted MR imaging of the liver: comparison of two high-resolution free-breathing imaging techniques with two breath-hold imaging techniques.
abstract: OBJECTIVE
  To evaluate image quality and accuracy for the detection of focal hepatic lesions depicted on T2-weighted images obtained with two high-resolution free-breathing techniques (navigator-triggered turbo spin-echo [TSE] and respiratory-triggered TSE) and two standard-resolution breath-hold techniques (breath-hold TSE with restore pulse and half-Fourier acquisition single-shot TSE [HASTE]).
  
  
  METHODS
  Our institutional review board approved this study, and written informed consent was obtained from all patients. Two readers independently reviewed 200 T2-weighted imaging sets obtained with four sequences in 50 patients. Both readers identified all focal lesions in session 1 and only solid lesions in session 2. The readers' confidence was graded using a scale of 1-4 (1 <or= 50%; 4 >or= 95%). The diagnostic accuracies of the four MR sequences were evaluated using the free-response receiver operating characteristic (ROC) method. Region-of-interest (ROI) measurements were performed for the mean signal intensity (SI) in the liver, spleen, hepatic lesions, and background noise.
  
  
  RESULTS
  The accuracy of navigator-triggered TSE and respiratory-triggered TSE was superior to that of breath-hold TSE with restore pulse and HASTE for the detection of all focal or solid hepatic lesions. The mean lesion-to-liver contrast-to-noise ratio (CNR) of solid lesions in navigator-triggered (P < 0.001) and respiratory-triggered TSE (P < 0.005) was significantly higher than that in HASTE.
  
  
  CONCLUSIONS
  High-resolution, free-breathing, T2-weighted MRI techniques can significantly improve the detectability of focal hepatic lesions and provide higher lesion-to-liver contrast of solid lesions compared to breath-hold techniques.
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Lee
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Byun
authors.forename: Hye-Suk
authors.initials: HS
authors.lastname: Hong
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Park
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Won
authors.forename: Yong Moon
authors.initials: YM
authors.lastname: Shin
authors.forename: Moon-Gyu
authors.initials: MG
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000378:metabolism* / Q000473:pathology*; D008107:Liver Diseases / Q000175:diagnosis / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009068:Movement; D012372:ROC Curve; D012119:Respiration