title: Liver MR imaging: comparison of respiratory triggered fast spin echo with T2-weighted spin-echo and inversion recovery.
abstract: BACKGROUND
  The purpose of this study was to compare a fast spin-echo sequence combined with a respiratory triggering device (R. trig. FSE) with conventional T2-weighted spin-echo (CSE) and inversion recovery (STIR) sequences for the detection of focal hepatic lesions.
  
  
  METHODS
  We performed a prospective study of 33 consecutive patients with known or suspected hepatic tumors. All patients underwent R. trig. FSE, CSE, and STIR imaging at 1.5 T. Acquisition times were 10.7 min for the CSE sequence and ranged from 12 to 15 min for STIR and from 5 to 7 min for R. trig FSE. For each sequence, liver-spleen contrast-to-noise ratio (CNR) and liver-lesion CNR were determined quantitatively. Image artifact and sharpness were graded by using a four-point scale on each sequence by two independent readers. Both readers also independently identified hepatic lesions (up to a maximum of eight per patient). For patients with focal lesions, the total number of lesions detected (on each sequence) and the minimum size of detected lesions were also determined by each reader.
  
  
  RESULTS
  No significant difference was detected between R. trig. FSE and CSE or STIR in either liver-spleen CNR or liver-lesion CNR. R. trig. FSE images were equivalent to CSE and superior to STIR in sharpness (p < 0.01) and presence of artifact (p < 0.01). R. trig. FSE detected a higher number of lesions (reader 1: n = 92, reader 2: n = 86) than CSE (reader 1: n = 70, reader 2: n = 69) and a significantly higher number than STIR (reader 1: n = 71, reader 2: n = 76). Lesion structure was significantly better defined with R. trig. FSE than with STIR (p < 0.01) and CSE (p < 0.05).
  
  
  CONCLUSIONS
  Compared with CSE and STIR, R. trig. FSE produces hepatic images of comparable resolution and detects an increased number of focal hepatic lesions in a shorter period of time.
authors.affiliation: Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Keogan
authors.forename: C E
authors.initials: CE
authors.lastname: Spritzer
authors.forename: E K
authors.initials: EK
authors.lastname: Paulson
authors.forename: S S
authors.initials: SS
authors.lastname: Paine
authors.forename: L
authors.initials: L
authors.lastname: Harris
authors.forename: J L
authors.initials: JL
authors.lastname: Dahlke
authors.forename: J R
authors.initials: JR
authors.lastname: MacFall
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016477:Artifacts; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000556:secondary; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D012119:Respiration; D013154:Spleen / Q000473:pathology; D014057:Tomography, X-Ray Computed