title: Reversed laminar appearance of articular cartilage by T1-weighting in 3D fat-suppressed spoiled gradient recalled echo (SPGR) imaging.
abstract: OBJECTIVE
  To investigate the reversed intensity pattern in the laminar appearance of articular cartilage by 3D fat-suppressed spoiled gradient recalled echo (FS-SPGR) imaging in magnetic resonance imaging (MRI).
  
  
  METHODS
  The 3D SPGR experiments were carried out on canine articular cartilage with an echo time (TE) of 2.12 msec, a repetition time (TR) of 60 msec, and various flip angles (5 degrees to 80 degrees ). In addition, T1, T2, and T2* in cartilage were imaged and used to explain the laminar appearance in SPGR imaging.
  
  
  RESULTS
  The profiles of T2 and T2* in cartilage were similar in shape. However, the T2 values from the multigradient-echo imaging sequence were about 1/3 of those from single spin-echo sequences at a pixel resolution of 26 mum. While the laminar appearance of cartilage in spin-echo imaging is caused mostly by T2-weighting, the laminar appearance of cartilage in fast imaging (ie, short TR) at the magic angle can have a reversed intensity pattern, which is caused mostly by T1-weighting.
  
  
  CONCLUSIONS
  The laminar appearance of articular cartilage can have opposite intensity patterns in the deep part of the tissue, depending on whether the image is T1-weighted or T2-weighted. The underlying molecular structure and experimental protocols should both be considered when one examines cartilage images in MRI.
authors.affiliation: Department of Physics and Center for Biomedical Research, Oakland University, Rochester, Michigan 48309, USA. xia@oakland.edu
authors.forename: Yang
authors.initials: Y
authors.lastname: Xia
authors.forename: Shaokuan
authors.initials: S
authors.lastname: Zheng
mesh_terms: D000273:Adipose Tissue; D000818:Animals; D002358:Cartilage, Articular / Q000033:anatomy & histology*; D004285:Dogs; D017352:Echo-Planar Imaging / Q000379:methods; D058430:Humeral Head / Q000033:anatomy & histology*; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D023421:Models, Animal; D012016:Reference Values; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000033:anatomy & histology
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