5. Musculoskeletal Imaging

Question 1

What is the advantage of X-ray in musculoskeletal imaging?

Answer 1

• most useful for skeletal diagnostics
• must have at least 2 views!!

Question 2

What is the advantage of CT in musculoskeletal imaging?

Answer 2

accurate assessment of osseous lesions and calcification; 3D reconstruction

Question 3

What is the advantage of MRI in musculoskeletal imaging?

Answer 3

imaging of joints, spine and soft tissue elements due to its great soft tissue resolution and multiplanar imaging

Question 4

What is the advantage of US in musculoskeletal imaging?

Answer 4

• has limited role in musculoskeletal imaging
• beneficial for joint effusion, blood flow and presence of foreign body within the superficial soft tissues

Question 5

What is the advantage of scintigraphy in musculoskeletal imaging?

Answer 5

• it provides physiological information on cell turnover so is useful for lesions throughout the skeleton
• examines osteoblast activity

Question 6

How does fibrous tissue appear on MRI?

Answer 6

• fibrous tissues: ligaments or tendons
• appears as hypointense (dark) on T1, T2, and proton density sequences

Question 7

Signal intensities on fat suppressed proton density images

Answer 7

fluid/edema = hyperintense
- pathological edema
- intraarticular fluid collection

mildly hypointense: hyaline cartilage, synovium

hypointense: collagen rich or fibrotic structures; structures w/o water/soft tissue content)
- meniscus, labrum
- ligament
- tendon
- bone cortex

Question 7

What is proton density imaging?

Answer 7

• shows the number of hydrogen protons in each voxel, providing great anatomical information but low contrast resolution
• tissues with higher concentration/density of protons appears bright on the image

Question 8

What are the radiological signs of acute fracture?

Answer 8

• disruption of the continuity of all or part of the bone cortex
• abrupt discontinuity of cortex
• acute angulation (two-view X-ray is mandatory!!)
• fracture lines are more lucent
• edges of a fracture tend to be jagged/rough

Question 9

What are the imaging modalities for traumatic injuries?

Answer 9

imaging modality is chosen according to the energy of the trauma

• high energy trauma: CT is first line modality
• low energy trauma: radiograph or eFAST are possible choices for injured regions

Question 10

What is the most commonly visualized joint by MRI?

Answer 10

knee joint

Question 11

What is the unhappy triad?

Answer 11

usually by a lateral force on the knee joint, it can lead to a torn medical meniscus, torn tibial collateral ligament, and torn anterior cruciate ligament

Question 12

How are isolated superficial ligaments best examined?

Answer 12

• by US (ie. achilles tendon rupture)
• rupture line would appear hypoechoic

Question 13

When is spinal imaging indicated?

Answer 13

• altered mental status
• neck pain
• tender to palpation
• neurological abnormality
• high risk due to the mechanism of injury

Question 14

What is the best mode of imaging for spinal trauma?

Answer 14

• CT is the primary modality to evaluate cervical spine injure; it has higher sensitivity and specificity (detects 97-100% of fractures)
• MRI’s are recommended in case of any neurological symptoms
• radiographs are not recommended because they detect only 60-80% fractures, even with 3 views

Question 15

Differentiating malignant and benign bone tumors

Answer 15

• benign: well-defined, geographic, sclerotic margin
• malignant: ill-defined, moth-eaten, permeative

Question 16

What are the imaging modalities of bone tumors?

Answer 16

• conventional radiography is the first line modality
• CT for cortical integrity
• MRI for tumor characterization, bone marrow visualization and staging
• bone scintigraphy to assess osteoblastic activity and multifocal lesions

Question 17

What is MR suitable for in bone tumors?

Answer 17

• exact tumor location
• soft tissue involvement
• enhancement
• relation to large vessels and nerves
• local lymph nodes

Question 18

Detection of skeletal metastases

Answer 18

• difficult on X-ray because a minimum of 30-50% bone mineral loss is necessary before it is visible and this is quite excessive
• bone scans are most sensitive for this, to detect sclerotic and lytic lesions (especially sclerotic)

Question 19

Imaging modality for osteomyelitis

Answer 19

• MR is highly sensitive and can detect osteomyelitis very early, even in a few days
• X-ray takes upto 2-3 weeks to be positive
• bone scan is typically for bone malignancies and metastatic diseases

Question 20

Treating septic arthritis

Answer 20

• septic arthritis should be treated immediately!!
• osteomyelitis can present to the emergency department as an acute, subacute or chronic orthopedic concern
• septic arthritis can lead to irreversible chondrolysis occurs within hours if left untreated
• fast radiography or US is used before surgical intervention

Question 21

What is the imaging modality for lower back pain?

Answer 21

• MRI is used for imaging intervertebral discs, the myelon and nerve roots
• cause of lower back pain is commonly disc herniation