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Whole knee joint T1 values measured in vivo at 3T by combined 3D ultrashort echo time cones actual flip angle and variable flip angle methods.

  • Author(s): Ma, Ya-Jun
  • Zhao, Wei
  • Wan, Lidi
  • Guo, Tan
  • Searleman, Adam
  • Jang, Hyungseok
  • Chang, Eric Y
  • Du, Jiang
  • et al.

Published Web Location

https://doi.org/10.1002/mrm.27510
Abstract

PURPOSE:To measure T1 relaxations for the major tissues in whole knee joints on a clinical 3T scanner. METHODS:The 3D UTE-Cones actual flip angle imaging (AFI) method was used to map the transmission radiofrequency field (B1 ) in both short and long T2 tissues, which was then used to correct the 3D UTE-Cones variable flip angle (VFA) fitting to generate accurate T1 maps. Numerical simulation was carried out to investigate the accuracy of T1 measurement for a range of T2 values, excitation pulse durations, and B1 errors. Then, the 3D UTE-Cones AFI-VFA method was applied to healthy volunteers (N = 16) to quantify the T1 of knee tissues including cartilage, meniscus, quadriceps tendon, patellar tendon, anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), marrow, and muscles at 3T. RESULTS:Numerical simulation showed that the 3D UTE-Cones AFI-VFA technique can provide accurate T1 measurements (error <1%) when the tissue T2 is longer than 1 ms and a 150 μs excitation RF pulse is used and therefore is suitable for most knee joint tissues. The proposed 3D UTE-Cones AFI-VFA method showed an average T1 of 1098 ± 67 ms for cartilage, 833 ± 47 ms for meniscus, 800 ± 66 ms for quadriceps tendon, 656 ± 43 ms for patellar tendon, 873 ± 38 ms for ACL, 832 ± 49 ms for PCL, 379 ± 18 ms for marrow, and 1393 ± 46 ms for muscles. CONCLUSION:The 3D UTE-Cones AFI-VFA method allows volumetric T1 measurement of the major tissues in whole knee joints on a clinical 3T scanner.

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