title: 3D isotropic turbo spin-echo intermediate-weighted sequence with refocusing control in knee imaging: comparison study with 3D isotropic fast-field echo sequence.
abstract: BACKGROUND
  Three-dimensional (3D) turbo spin-echo (TSE) images have been used in imaging of the extremities and comparable diagnostic performance to two-dimensional (2D) TSE images has been reported in several studies. However, comparison of the 3D isotropic TSE intermediate-weighted sequence and 3D FFE sequence in terms of image quality has not been investigated.
  
  
  OBJECTIVE
  To compare the image quality of a 3D isotropic TSE intermediate-weighted sequence with refocusing control (volume isotropic turbo spin echo acquisition [VISTA]) and a 3D isotropic fast-field echo (FFE) sequence of the knee joint.
  
  
  METHODS
  3.0 T knee MRI with VISTA and 3D FFE sequences was performed in 10 healthy volunteers (3 men, 7 women; age range 26-30 years). Two radiologists with specialties in the musculoskeletal system assessed tissue contrast between the fluid-cruciate ligament (F-L), fluid-meniscus (F-M), and fluid-cartilage (F-C) based on a 4-point scale (1, poor; 2, fair; 3, good; and 4, excellent). Statistical analysis for inter-observer agreement and differences in grades in tissue contrast between VISTA and 3D FFE images (Wilcoxon signed-rank) were performed. For a quantitative analysis, the signal-to-noise ratio (SNR) was obtained by imaging phantom and noise-only image. Image contrast ratios (CRs) were calculated between F-L, F-M, and F-C in volunteer images of VISTA and 3D FFE and compared statistically with a paired t-test.
  
  
  RESULTS
  Based on qualitative analysis, VISTA had statistically superior grades of tissue contrast in F-L (P < 0.001) and F-M (P < 0.001). 3D FFE had superior but not statistically significant (P = 0.317) grades in F-C. Based on quantitative analysis, the SNR of the phantom imaging was higher in VISTA than that in 3D FFE (28.18 vs. 14.90). VISTA had superior CRs in F-L (P < 0.001) and F-M (P < 0.001). 3D FFE had superior CR in F-C (P = 0.038).
  
  
  CONCLUSIONS
  The VISTA sequence was superior in tissue contrast between F-M and F-L, and 3D FFE was superior in tissue contrast between F-C, subjectively and quantitatively.
authors.affiliation: Department of Radiology, School of Medicine, Sungkyunkwan University, Seoul, Korea.
authors.forename: Jung Min
authors.initials: JM
authors.lastname: Seo
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Yoon
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Kwon
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D019047:Phantoms, Imaging; D012016:Reference Values; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D018709:Statistics, Nonparametric