Musculoskeletal Imaging – The Basics

1. Musculoskeletal Imaging – The Basics Dr Harsha Kumar 3rd year Radiology resident

2. MSK Imaging – Imaging Modalities • Plain Radiographs • Nuclear Scintigraphy • Ultrasound • Computed Tomography • Magnetic Resonance Imaging

3. Plain Radiographs • Widely available • Reproducible • Patient friendly • ‘Inexpensive’ • Usually the indicated primary imaging modality

4. Plain Radiographs • Standard protocols available • Consider the pathology in question • Image area of question, not the vicinity • “One view is No view” • Supplemental views possible in most locations

6. Plain Radiographs - Obvious

7. Plain Radiographs – 2 views

8. Plain Radiographs – 2 views Posterior Dislocation

9. Plain Radiographs – Extra views Radial Head Fx

10. Plain Radiographs – Extra views Scaphoid Fx

11. Nuclear Scintigraphy • Most common = Bone Scan • Very sensitive for skeletal pathology • Mildly sensitive for soft tissue pathology • Usually nonspecific as an isolated test • Mostly patient friendly; no significant environmental exposure • Small-moderate expense

12. Nuclear Scintigraphy • Excellent for specific pathologies • Osteomyelitis • Metastases – Not Multiple myeloma • Occult fracture • Reasonably reassuring • Normal is usually normal

13. Nuclear scintigraphy – Bone Scan • IV injection radioisotope (Tc-99m) bound to phosphate +/- dynamic imaging • Approx 3 hour delay • Delayed static imaging with a superficial detector

15. Nuclear Scintigraphy – Bone Scan Osteomyelitis

16. Nuclear Scintigraphy 2nd MT stress fracture

17. Ultrasound • Not available at all institutions • Reproducible in trained hands • Excellent for superficial soft tissue elements including tendons and muscle • Patient friendly • Small to moderate expense

18. Ultrasound • Routine exam room equipped with adequate imaging devices • Superficial gel (standard or aseptic) application with touch with transducer • Usually static exam of architecture +/- vascularity assessment • Potential for dynamic imaging

20. Ultrasound Cephalad Ceph Caud Calcaneus Caudad

21. Ultrasound – Achilles Tendon Intrasubstance tear

22. Ultrasound – Patellar tendon Proximal patellar tendonitis – Jumper’s Knee

23. Computed Tomography (CT) • Widely available • Reproducible, although variety of techniques • Excellent bone assessment • Occasionally useful for soft tissue assessment • Patient friendly • Moderate expense • Interventional options

24. Computed Tomography • Usually supine axial exam, with some alternative positioning options • Can develop reformatted images after exam for alternative views • Imaging time in seconds, rarely minutes • Usually without IV or oral contrast

26. CT - Fractures Scaphoid fracture

27. CT - Dislocation Lis Franc Fx/Dislocation

28. CT – Bony anomalies Midsubtalar coalition

29. Magnetic Resonance Imaging • Widely available, but non-standardized imaging techniques • Reproducible • Excellent for soft tissue pathology • Good-excellent for bone pathology • NOT patient friendly • Large expense

30. MRI – Absolute Contraindications • Cardiac Pacemakers • Electronic stimulators • Metallic foreign bodies in the orbit • Body habitus beyond limits of physical unit • Huge listing maintained in MRI facility

31. MRI - Relative Contraindications • Penile prostheses • IUD’s • Cardiac valves • Berry aneurysm clips • Retained bullet fragments • Claustrophobia • Huge listing in MRI facility

32. MRI • Usually performed with patient supine • Multiplanar imaging obtained without changing position • One exam = one body part • Average exam time 45 minutes; most patients can’t last >2 hours • Strict guidelines for sedation • Optional contrast – Rad usually decides for body imaging

34. MRI – Trauma Femoral Neck Fracture

35. MRI – Internal Derangement Supraspinatus tear= Full thickness, Full width Coronal PD Coronal T2

36. MRI – Internal Derangement Sagittal, Meniscus NL Posterior Horn Tear

37. Imaging • Plain radiographs are usually the starting point • Most x-ray protocols work for most situations; Consider suppl. Views • Secondary imaging techniques have specific advantages and disadvantages • A specific question is more likely to get you a direct answer

38. Know what to order • Know what an optimal imaging series is and accept no less • Know a good image from a poor one and accept only the good

39. …and… • Read by check list • Know the common lesions • Know the commonly MISSED lesions

40. The Musculoskeletal System • Soft tissues: muscles, ligaments, tendons, bursae, skin and subcutaneous tissue • Joints: capsule, synovium, articular cartilage • Bones: cortex, cancelleous, medullary canal

41. BODY COMPOSITION AIR: Black Examples- trachea, lungs, stomach, digestive tract FAT: Gray black Examples- subcutaneously along muscle sheaths; around viscera

42. Continued WATER: Gray Examples: Muscles, nerves, tendons, ligaments, vessels (All of these structures have the same density and therefore are hard to distinguish on plain xrays.)

43. Continued BONE: Gray/White CONTRAST MEDIUM: White Outline HEAVY METALS: White Solid

47. Bones: components • Epiphysis • Physis (growth plate) • Metaphysis • Diaphysis • Apophysis

48. cortex medullary cavity

49. corocoid acromion greater tuberosity clavicle lesser tuberosity glenoid fossa

50. Joints: components • Fibrous capsule • Synovial lining • Articular cartilage • Subchondral bone