title: 3D-MRI of the ankle with optimized 3D-SPACE.
abstract: OBJECTIVE
  To assess the use of 3-dimensional (3D) MR imaging of the ankle with the 3D-turbo-spin-echo-sequence 3D-"Sampling Perfection with Application optimized Contrast using different flip angle Evolutions" (SPACE), as compared with 2-dimensional-turbo-spin-echo-sequence.
  
  
  METHODS
  After internal review board's approval and informed consent, 15 healthy volunteers and 45 consecutive patients were examined at 3 T with isotropic fat-saturated moderately T2-weighted 3D-SPACE (voxel size: 0.6(3) mm(3)/acquisition time: 6:43 minutes) featuring radial k-space reordering for optimized contrast. Signal- and contrast-to-noise ratios (SNR; CNR, respectively) were calculated with the subtraction method. Using free 3D reconstructions, 2 radiologists independently assessed depiction of cartilage, ligaments, and tendons, as well as detection and grading of abnormalities of these structures (5-point Likert scale) compared with conventional 2-dimensional-TSE-sequences (voxel size: 0.4 × 0.4 × 3 mm(3)/total acquisition time: 11 minutes). Statistical analysis was performed with Wilcoxon signed rank tests, 95% and 99% confidence intervals and weighted κ coefficients.
  
  
  RESULTS
  SNR and CNR of fluid/cartilage were significantly higher for 3D-SPACE (P < 0.05). The isotropic voxel size facilitated improved depiction of the medial and lateral ankle ligaments with significant differences for the calcaneofibular ligament and the anteromedial ligament complex (P < 0.05). In the patient cohort, cartilage and spring ligaments were also significantly better depicted (P < 0.05). However, there were no significant differences in the number or in the diagnostic confidence of detected cartilage, ligament, or tendon abnormalities. Interreader correlation was good (κ = 0.69-0.71) for both sequences. The correlation between the 2 sequences was excellent (κ = 0.84-0.85).
  
  
  CONCLUSIONS
  3D-SPACE allows 3D acquisition and assessment of the ankle and facilitates depiction of the complex ankle anatomy at sufficient SNR and CNR.
authors.affiliation: Department of Clinical Radiology, University Hospitals Munich, Munich, Germany. mike.notohamiprodjo@med.uni-muenchen.de
authors.forename: Mike
authors.initials: M
authors.lastname: Notohamiprodjo
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kuschel
authors.forename: Annie
authors.initials: A
authors.lastname: Horng
authors.forename: Dominik
authors.initials: D
authors.lastname: Paul
authors.forename: Peter
authors.initials: P
authors.lastname: Baer
authors.forename: Guobin
authors.initials: G
authors.lastname: Li
authors.forename: José Maria Raya
authors.initials: JM
authors.lastname: Garcia del Olmo
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.forename: Christian
authors.initials: C
authors.lastname: Glaser
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000843:Ankle Joint / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity