title: Fat suppression gradient-echo magnetic resonance imaging of experimental articular cartilage lesions: comparison between phase-contrast method at 0.23T and chemical shift selective method at 1.5T.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of a newly developed single-scan phase-contrast water-fat imaging technique for fat suppression at 0.23T open magnet, compared to the conventional chemical shift selective fat suppression method at 1.5T, in the detection of experimental articular cartilage lesions.
  
  
  METHODS
  Sixty regions of 20 knee joint specimens of pigs with artificially created articular cartilage lesions were examined with 0.23T and 1.5T MR scanners. Sagittal fat-suppressed three-dimensional gradient-echo (3D GRE) images, obtained with the phase-contrast method at 0.23T, and fat-suppressed three-dimensional spoiled gradient recalled echo (3D SPGR) images, obtained with a chemical shift selective method at 1.5T, were evaluated. Diagnostic performance was analyzed. The conspicuity of the lesions, the amount of artifacts, and the uniformity of fat suppression were evaluated. The contrast-to-noise (CNR) values of cartilage-to-bone marrow, and cartilage-to-infrapatellar fat were calculated.
  
  
  RESULTS
  At 0.23T, sensitivity and specificity were 80% and 95% for partial cartilage lesions (grade 2), and 91% and 100% for full-thickness lesions (grade 3). At 1.5T, sensitivity and specificity were 85% and 95% for grade 2 lesions, and 96% and 97% for grade 3 lesions. No significant difference was detected in the conspicuity of lesions. The uniformity of fat suppression was more constant with 3D SPGR images compared to 3D GRE images. More susceptibility artifacts, derived from the procedure of creating lesions, were detected at 1.5T. The cartilage-to-fat CNRs were significantly higher with high-field images.
  
  
  CONCLUSIONS
  Phase-contrast method for fat suppression at 0.23T is a useful technique in detecting articular cartilage lesions.
authors.affiliation: Department of Diagnostic Radiology, University Hospital of Oulu, Oulu, Finland. kari.palosaari@oulu.fi
authors.forename: Kari
authors.initials: K
authors.lastname: Palosaari
authors.forename: Risto
authors.initials: R
authors.lastname: Ojala
authors.forename: Roberto
authors.initials: R
authors.lastname: Blanco-Sequeiros
authors.forename: Osmo
authors.initials: O
authors.lastname: Tervonen
mesh_terms: D000818:Animals; D016477:Artifacts; D002358:Cartilage, Articular / Q000473:pathology*; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007718:Knee Injuries / Q000473:pathology; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D012680:Sensitivity and Specificity; D013552:Swine