MUSCULOSKELETAL IMAGING FOR PHYSICAL THERAPISTS. COMBINED SECTIONS MEETING 2006 San Diego, CA February 1-5, 2006

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1 MUSCULOSKELETAL IMAGING FOR PHYSICAL THERAPISTS COMBINED SECTIONS MEETING 2006 San Diego, CA February 1-5, 2006 John Meyer, DPT, OCS University of Southern California Department of Athletic Medicine Los Angeles, California Handout Length 12 Pages 1

2 Musculoskeletal Imaging for Physical Therapists Presentation Objectives: Recognize common views on various imaging studies (X-ray, MRI) Identify relevant anatomy Learn a specific reading process to recognize common pathologies in the spine, shoulder and knee. Discuss how to utilize information from the images to guide clinical decisions Cervical Spine X-Ray Standard Views: A/P Open Mouth A/P Lateral Left A/P Oblique LAO: Left side near the film pt. rotated anterior and you will visualize the open left IVF. The side marker will be placed behind the spine, which tells you it is an anterior film. LPO: Left side near the film pt. rotated posterior and you will visualize the open right IVF. The side marker will be placed in front of the spine, which tells you it is a posterior film. Right A/P Oblique RAO: Right side near the film pt. rotated anterior and you will visualize the open right IVF. The side marker will be placed behind the spine, which tells you it is an anterior film. RPO: Right side near the film pt. rotated posterior and you will visualize the open left IVF. The side marker will be placed in front of the spine, which tells you it is a posterior film. Flexion Extension 2 views or films are required to be a legal document. AP Open Mouth X-ray View Reading Process 1. Dens or Odontoid Process 2. Lateral Mass of Atlas 3. Transverse Process of Atlas 4. Atlantoaxial Joint Space 5. Anterior Arch of Atlas 6. Posterior Arch of Atlas 7. Body of C-2 8. Spinous Process of C-2 2

3 Common Upper Cervical Spine Pathology: Odontoid Fractures: Type I: A stable oblique fracture through the upper part of the odontoid Type II: An unstable transverse fracture through the base of the odontoid Type III: A stable fracture through the base of the odontoid extending into the body of the axis Jefferson Fractures: Result of axial loading on a head through the occiput leading to a burst type fracture of C1 There is disruption of the lateral masses of C1 and the transverse ligament. Diving is the most frequent cause of these fractures other causes include a motor vehicle accident or falls onto the head On the open mouth x-ray you will see overhang on one or both sides of the lateral masses of C1 AP Lower Cervical X-ray Reading Process 1. Identify T1 transverse Process 2. Trace C7 transverse process looking for a cervical rib 3. Check the uncinate processes 4. Block head vertebral body reading process 5. Spinous processes and pedicles 6. Check the discs for height and color 7. Trace the tracheal air space 8. Check the soft tissue IVF: Formed by the following components Roof: Pedicle Floor: Pedicle Anterior wall: Uncinate process Posterior wall: Facet joint Clinically it is helpful to assess the uncinate processes for arthritic changes and use this information to guide manual therapy treatment Lateral Cervical X-ray Reading Process 1. Check the Atlanto-odontiod space 2. Check the height of the dens 3. Trace the dens including the base looking for fracture 4. Check for a posterior ponticle 5. Trace the front of the vertebrae Anterior vertebral line 6. Trace the back of the vertebrae Georges Line 7. Trace the spinolaminar line 8. Trace the spinous processes line 3

4 9. Trace the body of the vertebrae 10. Check the disc spaces 11. Check the pedicles 12. Check the facets 13. Check the spinous process spacing 14. Check the soft tissues 3 spaces are evaluated AOI no >3mm, if greater than 3mm upper cervical instability is present Retropharyngeal space: 7 mm Retrotracheal space: mm These spaces are often enlarged after cervical trauma or MVA 4 main lines are observed 1. Anterior vertebral line 2. Posterior vertebral or Georges line 3. Spinolaminar line 4. Spinous process line The distance between the posterior vertebral body line and the spinolaminar line represents the sagittal dimension of the spinal canal. >15 mm is normal <12 mm is considered stenosis Common Mid-Cervical Pathology: Hangman s Fracture: A fracture of the pedicle of C2 Best seen on a lateral view Burst Fractures: The nucleus pulposus is driven through the fractured end plate into the vertebral body; the body explodes from within and results in a comminuted fracture. A vertical split in the vertebral body on an AP x-ray characterizes it. It is easier to see on a lateral x-ray or CT. Teardrop Fracture: Usually caused by a flexion compression injury Fracture of the posterior elements and posterior displacement of the involved vertebrae Stress is applied to the ALL and causes it to either rupture or avulse from the vertebral body. A triangular or teardrop shaped fragment is displaced anteriorly and inferiorly Best seen on a lateral view, most severe and unstable cervical fracture 4

5 Clay-Shoveler s Fracture: Spinous process fracture of C6, C7, or T1 Result of a hyperflexion injury Degenerative Joint Disease: Non-uniform loss of joint space, osteophytes, subchondral sclerosis, deformity and subluxation are the 5 general radiological features of DJD. Oblique Cervical X-ray Reading Process 1. Vertebral Bodies 2. Transverse Process 3. Intervertebral Foramen C2-C3 is the first IVF you see. C3 nerve root exits here. 4. Facet joints In the cervical spine anterior oblique films view the same side structures, posterior oblique films view the opposite side structures Flexion Extension X-ray Reading Process 1. Look at the 3 lines of alignment 2. Look at the space between spinous processes for irregularities. 3. Check the AOI Canadian Cervical Spine Rules Canadian cervical spine rules (100% sensitivity and 43% specificity for identifying important cervical injuries) (6) Cervical and Lumbar MRI Examination Cervical and Lumbar MRI Signal Contrasts Water is bright on a T2 image Fat is bright on a T1 image Vertebral bodies: The signal intensity of the vertebral body depends on the marrow content of the vertebral body. T1 image, the vertebral body will image bright T2 image, the vertebral body will image low signal intensity After radiation treatment, the bone marrow is replaced with fat and the vertebral bodies are brighter on T1 images Discs: The spinal discs show low signal on T1, high signal on T2 The nucleus is brighter because of greater water content Degenerative disc disease is a progressive decrease in signal intensity. Ligaments: 5

6 The spinal ligaments demonstrate a low signal intensity on T1 and T2 because of there high collagen content except for the ligamentum flavum. Spinal Cord and CSF: T1 image the cord has an intermediate signal T2 image the cord has a low signal CSF low signal on T1 (lower than the spinal cord) CSF high signal on T2 Cervical and Lumbar Spine MRI Common Views T1-weighted sagittal T2-weighted sagittal T1-weighted axial T2-weighted axial Cervical Sagittal View MRI Evaluation 1. Cranio-vertebral junction 2. Atlanto-axial articulation 3. Spinal cord 4. Bone Marrow 5. Disc: Hydrated, Desiccated or Displaced 6. Endplates 7. Alignment Cervical Axial View MRI Evaluation 1. Foramina 2. Disc 3. Spinal Cord Lumbar Sagittal MRI Evaluation 1. Conus 2. Bone marrow Normal bone marrow signal is higher than muscle or disc on T1 Marrow proliferation disorders Multiple myeloma Leukemia Abnormal findings include a signal in the bone that is equal or lower than muscle on T1 3. Endplates 4. Disc: Hydrated, Desiccated or Displaced 5. Foramen Lumbar Axial MRI Evaluation Number the axial pedicles, the pedicles are the key to the spine and knowing where you are L5 has angled pedicles, L4 pedicles are vertical 6

7 You can only see from the bottom of L3 to the top of S1on the axial images so you have to look at L1 L2 L3 on the sagittal 1. Facets 2. Foramen 3. Pedicle 4. Disc 5. Spinal cord 6. Paraspinals and psoas Look for atrophy, fat or abscesses Common Cervical and Lumbar Spine Pathology: Disc Disease Herniation: A term originally meaning a focal protrusion, the meaning of which has become blurred, and which now seems to include bulge, protrusion, extrusion and osteophyte formation Bulge: Broad based disc displacement Usually degenerative No evidence that this occurs acutely Protrusion: Focal disc displacement Connection to native disc of similar dimension May or may not be acute Extrusion: Focal disc displacement Connection to native disc attenuated or absent Sequestered or floating disc Spinal Stenosis Narrowing of the central spinal canal, neural foramen, lateral recess or any combination of these anatomic regions, by soft tissue or osseous structures that impinge on neural elements Standard classification for stenosis is based on cause Congenital: (e.g., short pedicles) Acquired: degenerative Causes of Spinal Stenosis Congenital Osteophytes Alignment abnormalities Ligament or facet hypertrophy Disc abnormalities 7

8 Levels of Stenosis Central Lateral recess Foraminal Diagnosis Depends on size of canal Measurements are not always taken. The diagnosis is made via the shape of the canal and thecal sac. Normally round or oval on axial images Quantify as mild, moderate or severe Must correlate imaging studies with clinical examination May produce myelopathy or radiculopathy Knee MRI Common Views and Signal Contrasts MRI of the knee is the most frequently requested MR joint study in musculoskeletal radiology. It has proven to be very accurate, with sensitivity/specificity in the 90%to 95% range for the meniscus and close to 100% for the cruciate ligaments. (2) Common Views Sagittal Axial Coronal Signal Contrasts Reminder Fat, bright on T1 Water, bright on T2 Appearance of Articular Cartilage Bright on Fat Suppressed Sequences Low to intermediate signal on T1 and T2 MR Signal of Joint Fluid or Marrow Edema Low on T1 High on T2 High on most fat suppressed sequences MR Appearance of Ligaments and Tendons Low on T1 Low on T2 Low on Suppressed sequences 8

9 Knee MRI Reading Process 1. Bone marrow. 2. Synovium. 3. Articular cartilage. 4. Collaterals. 5. Cruciates. 6. Extensor mechanism. 7. Meniscus. Common Knee Pathology: Bone Marrow Infarcts, Edema and Joint Fluid Bone marrow edema is often the result of trauma and there is a strong likely hood of fracture Bone marrow infarcts can be found in individuals who use steroids or work in high pressure environments (divers) Soft Tissue Masses Popliteal or Baker s cysts High signal on T2 Low signal on T1 Commonly associated with meniscal tears and degenerative joint disease Articular Cartilage Articular cartilage appears intermediate in signal intensity on T1/T2-weighted or proton density images with fat saturation It is distinguishable from the dark signal of the adjacent osseous cortex and the bright signal of joint fluid Cartilage defects of the tibia or femur are best seen on the sagittal and coronal images, whereas patellar abnormalities are best demonstrated on the axial images These defects are seen as surface irregularities filled with joint fluid MCL and LCL Injury The MCL (medial collateral ligament) is typically divided into layers The first layer is the superficial fibers The second layer is bursa and fat The third layer is the deep fibers, it is attached to the capsule and the mid portion of the medial meniscus The LCL (lateral collateral ligament) is a capsular thickening but is separated from. the capsule. This well defined cord extends from the lateral condyle to the fibular head. When this ligament is torn, it is not uncommon to see an ACL or PCL tear ACL and PCL Injury The cruciates are best evaluated on a T2 image The ACL has multiple fibers that will show up as linear areas of low signal intensity 9

10 High signal intensity will be seen in acute lesions. Chronic tears are seen as areas of intermediate signal intensity The PCL is thicker and has a more uniform low signal intensity PCL tears are usually mid substance Extensor Mechanism Injury Patellar tendon tear Jumpers Knee Patellar tendonitis Quadriceps tendon Patellar articular surface The extensor mechanism is easily seen on sagittal images Inflammation may result in thickening with increased signal intensity. Complete tears are high signal intensity with tendon separation. Jumper's knee: Assessment of the quad tendon and patellar tendon can be done on sagittal and axial images Meniscus Injury Criteria For Meniscal Tear 1. Gross morphologic abnormality 2. Intra-meniscal signal reaching an articular surface Type of meniscus tears: 1. Degenerative - a horizontal tear. 2. Linear tear. 3. Bucket handle. 4. Flip. 5. Meniscus cyst. 6. Discoid meniscus Bucket Handle Large fragment in notch Absent body of medial meniscus Double PCL Sign Shoulder MRI Common Views Coronal Oblique Axial Sagittal Oblique Shoulder MRI Normal Anatomy and Signal Contrasts Tendons and ligaments are normally low signal intensity on all pulse sequences The subacromial bursa is outlined by fat and should not be distended with fluid 10

11 Shoulder MRI Coronal Oblique View Reading Process 1. Bone Marrow Hill Sachs Lesion: Impaction fracture posterolateral aspect of the humeral head from anterior shoulder dislocation Best seen on an axial in the first 2 slices through the humeral head or the coronal image Posterior impingement cyst: This condition refers to impingement of the infraspinatus and supraspinatus tendons between the humeral head and the posterior glenoid rim during overhead movements with abduction and ER. Degenerative cysts and possible R/C tears are found on MRI 2. Synovium 3. Infraspinatus 4. Supraspinatus 5. AC Joint 6. Acromion 7. Deltoid 8. Biceps 9. Labrum Superior Inferior Common Shoulder Pathology: R/C Tear MRI sensitivity =97% (7) Biceps Tear MRI sensitivity poor to moderate (5) Superior Labral Tear MRI Arthrogram sensitivity =89% (1) Shoulder MRI Axial View Reading Process 1. Long Head of Biceps 2. Labrum Anterior Posterior 3. GHJ Ligaments Superior Middle Inferior Shoulder MRI Sagittal Oblique View Reading Process Use to confirm your findings from the other views 1. Supraspinatus 2. Infraspinatus 3. Teres Minor 4. Biceps 5. Subscapularis 6. Acromion 11

12 References 1. Bencardino JT, Beltran J, Rosenberg ZS, et al: Superior labrum anteriorposterior lesions: Diagnosis with MR arthrography of the shoulder. Radiology214: , Berquist, TH. MRI of the Musculoskeletal System, 4th edition. Philadelphia: Lippincott Williams & Wilkins, Greenspan, A. Orthopedic Radiology: A Practical Approach, 3rd edition. Philadelphia:Lippincott Williams & Wilkins, Kaplan PA, Helms CA, Dussault R, Anderson MW, Major NM. Musculoskeletal MRI. WB Saunders, Mohtadi NG. Vellet AD. Clark ML. Hollinshead RM. Sasyniuk TM. Fick GH. Burton PJ. A prospective, double-blind comparison of magnetic resonance imaging and arthroscopy in the evaluation of patients presenting with shoulder pain. [Journal Article] Journal of Shoulder & Elbow Surgery. 13(3):258-65, Stiell IG, Wells GA, Vandemheen KL, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA. 2001;286: Teefey SA, Rubin DA, Middleton WD, Hildebolt CF, Leibold RA, Yamaguchi K. Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases.j Bone Joint Surg Am. 2004;86-A: