Practical Interpretation  of   Knee MRI Routine MRI protocol Sagittal,Coronal,Axial Spin echo(SE) FSE,STIR T1, T2, PD TR 和TE 决定成像加权短TE 长TE 短TR  T1  无用途长TR  PD T2 Tissue characterization  T1  T2 Adipose tissue Fat white gray Yellow marrow Water  dark  white Cortical bone black black Cartilage  gray  gray Tendon / ligament/meniscus  black/gray black/gray Muscle  gray  gray Hematoma  white  white Chronic hemorrhage dark  dark  Anterior Cruciate Ligament extension ER 15°—20° direct sign of torn ACL Avulsion fx Indirect Bone bruise sign Deep sulcus sign Segond fx generalized increase in  signal intensity thickness  increase Anterior drawer sign Acute hemarthrosis Buckling of PCL pivot-shift pattern Associated soft tissue injuries Posterior horn of medial meniscus Bucket handle tear MCL Posterior Cruciate Ligament Primary sign of PCL Associated ligament injury ACL injury MCL injury PLC/LCL injury Collateral ligament Iliotibial band Biceps tendon Menisci Criterial to detect meniscal tear grade 3 signal abnormal meniscal morphology displaced or missing meniscal tissue meniscocapsular separation missing fragment Displaced fragment MRI signs absent bow ties sign(1 or fewer) double PCL sign large anterior horn sign too many bow ties(3 or more) notch sign Pitfalls in meniscus diagnosis Grade II signal Transverse meniscus lig. Popliteal hiatus Meniscofemoral lig. Bursa or fat plane of MCL 内侧半月板后角的上隐窝垂直光滑不连通Bone Marrow Edema(BME) pivot-shift injury dashboard injury hyperextension injury: ”kissing sign”clip injury patellar dislocation OCD popliteal cyst Meniscus cyst PVNS cruciate cyst ACL cyst Patellar dislocation Large & degeneration ant.horn 3 or more bow-ties Bucket handle tear double PCL sign discoid meniscus 3 or more bow-ties Popliteal hiatus Postoperative Meniscus  Grade 3 signal on T1-weighted images only is indeterminate for tear: it may represent postoperative change or retear of the meniscus Grade 3 signal on a T1-weighted image that is bright as  fluid on a T2-weighted image is diagnostic of retear.  A displaced meniscal fragment is diagnostic of retear.  Grade 3 signal in new a location is diagnostic of retear clip injury patellar dislocation Meniscus-Femoral ligament complete tear partial tear “peel off ”injury Complete tear Grade1 Grade3 Grade2 partial tear Secondary sign of PCL injury bone marrow edema(BME) avulsion fx Dashboard injury sign Bone Marrow Edema Tibial avulsion fx Normal Anatomy of MCL Grading MCL Injuries Grade 1 (sprain) Grade 2 (partial tear) Grade 3 (complete tear) Normal Anatomy of the LCL Complex/ Posterolateral Corner Complex LCL Popliteal m.complex Visible disruption of one of the posterolateral capsule structures Extensive surrounding soft tissue edema Avulsion fracture or marrow edema involving  the medial aspect of the fibular head Signs of Posterolateral Corner Injury bow ties < 2 triangular rectangular Grade III meniscus tear small PHMM www.book118.com 北京积水潭医院关节镜组JST Coronal: T2FFE  T2 STIR Saggital: T1 T2  T2FFE  T2 STIR T1 weighted image  (TR<1000msec,TE<40msec) “anatomy”T2 weighted image  (TR>1500msec,TE>60msec) “pathology”Fat suppression Chemical saturation Short tau inversion recovery (STIR) Normal MR appearance  discontinuity abnornal orientation (fallen ACL) nonvisualization Kissing sign Segond sign Deep sulcus sign > 2mm generalized increase in signal intensity thickness increase Buckling of PCL nonspecific Ant.drawer sign Normal MR appearance * * *