Knee Cartilage Injury Magnetic Resonance Double-echo Steady State Sequence Parameter Optimization And Applications

Object ive1. By changing FA of the MR3D-DESS sequence imaging parameters, explore the correlation value of the FA of3D-DESS sequence imaging parameters and contrast-to-noise ratio (CNR) of cartilage and synovial fluid on1.5T high-field MR machine conditions.2. To explore the diagnostic accuracy and clinical application value of3D-DESS sequence for knee cartilage damage with arthroscopy as the diagnostic criteria for the control MRI3D-DESS,3D-FLASH and2D-TSE-T2WI sequences of imaging diagnosis,Methods1.20healthy adult volunteers of between18-35years age are invited for cartilage imaging of the knees. The equipment is the Siemens1.5T Magnetom Avanto whole body superconductive magnetic resonance imager. Scanning sequence includes6group3D-DESS imaging sequences with different FA. The performance of articular cartilage and fluid in each group are observed, and signal-to-noise ratio (SNR) of cartilage, CNR of cartilage and synovial fluid among diffrent sequences are calculated and compared。2. MR3D-DESS,3D-FLASH and2D-TSE-T2WI sequences are performed for knee lesions of30patients who will undergo arthroscopy. Retch’s MRI grading standards and Outerbridge arthroscopy classification of knee cartilage are used. All patients are checked by knee arthroscopy in two weeks after the MRI examination.In addition to I classification standard for the swelling and softening of cartilage, the rest is the same to the MRI grading standards. With comparison of arthroscopic results(0grade is negative, Ⅰ-Ⅳ grade positive), the diagnostic sensitivity, specificity and Kappa value of three sequences were calculated.Results1.Healthy adult volunteers-SNR and CNR of knee cartilage and fluid following:Sequence1(ie, FA10°) SNR=88.4±15.4, CNR=7.1, Sequence2(ie, FA30°) SNR=134.6±11.2, CNR=11.2, sequence3(ie, FA45°) SNR=134.0±8.7, CNR=40.4, sequence4(ie, FA60°) SNR=113.6±7.2, CNR=69.1, sequence5(ie, FA75°) SNR=101.4±6.8, CNR=48.7, sequence6(ie, FA90°) SNR=86.8±6.0, CNR=32.2.2. Cases-compared with results of MRI examination and arthroscopic findings, the diagnostic sensitivity, specificity and Kappa values of three sequences were:3D-DESS sequence-93%,95%,0.752;3D-FLASH sequence-83%,92%,0.679;2D-TSE-T2WI sequence-74%,94%,0.617.Conclusion1.When the FA of the3D-DESS sequence is60-degree, the CNR of articular cartilage and fluid is the highest, and SNR of cartilage is higher, which is the most optimal form as a parameter. Application of3D-DESS sequence can detect early minor cartilage lesions.2.The diagnostic accuracy of3D-DESS sequence is the highest of3D-FLASH sequence and2D-TSE-T2WI sequence in the knee cartilage damage imaging.3D-DESS sequence has a good agreement with the diagnosic results of arthroscopy.The articular cartilage itself has the higher SNR in DESS sequence. And DESS sequence is able to enhance CNR of surround structures (especially the CNR of cartilage-synovial fluid). So DESS sequence has relatively more comprehensive, more practical and higher application value in the knee cartilage imaging.