MSK Imaging

Question 1

Describe the radiation dose the patient receives from an X-ray for every 1000 photons

Answer 1

For every 1000 photons reaching the patient, 100-200 photons are scattered. Just 20 reach the image detector. The rest are absorbed by the patient.

[radiation dose ~800-900?]

Question 2

______ uses continuous x-ray imaging to create a real-time look into internal structures and is useful for dynamic procedures such as injections, biopsies, angiograms, and GI evaluations

Answer 2

Fluoroscopy

Question 3

Imaging modality made up of superimposed 2D imaging with plain radiographs; able to measure and display varying x-ray attenuations of the tissues in a section of the body by passing through the section from different angles and reconstructing the image

Answer 3

CT

Question 4

Strengths vs. weaknesses of CT

Answer 4

Strengths: fast, good resolution of bony lesions, less expensive than MRI

Weaknesses: ionizing radiation, expensive, poor soft tissue contrast

Question 5

Between T1 and T2 weighted MRIs, which one results in water showing up relatively bright and fat relatively dark?

Answer 5

T2 weighted

[T1 weighted show fat relatively bright and water relatively dark]

Question 6

Between T1 and T2 weighted MRIs, which one is better for detecting pathology?

Answer 6

T2, because it fluid (edema) shows up bright white

[as a general rule, T1 are better for detecting anatomy, T2 are better for detecting pathology]

Question 7

Strenghts vs. weaknesses of MRI

Answer 7

Strengths: no ionizing radiation, entire cross-sections without interference, superior soft tissue contrast

Weaknesses: subject to motion artifact, inferior to CT in detecting acute hemorrhage, inferior to CT in detection of bony injury, requires prolonged acquisition time for many images

Question 8

Imaging modality used to help elucidate tears in labrum or cartilage; contrast medium is injected into joint under fluoroscopy

Answer 8

MRI or CT arthrogram (contrast used depends on whether it is CT or MRI)

Question 9

How does a normal tendon appear on ultrasound?

Answer 9

Hyperechogenicity and fibrillary

Question 10

Examples of MSK pathology that may be viewed using ultrasound include tendon and muscle pathologies. Ultrasound can show full thickness tears in tendons. It can also show muscle disruption +/- hematoma. How would a hematoma show up on ultrasound?

Answer 10

Anechoic or hypoechoic area

Question 11

What is a DEXA scan and how is it generated?

Answer 11

Dual Energy X-ray Absorption

Radiograph tube generates photon beams of 2 different energy levels, thus the term “dual-energy”. The difference in attenuation of the 2 photon beams as they pass through body tissue of variable composition distinguishes bone from soft tissue and allows quantification of bone mineral density (BMD)

Question 12

What is the difference between the uses of a T-score and a Z-score that are generated from a DEXA scan?

Answer 12

T-score = used for diagnosis of osteoporosis

Z-score = used to compare the patient’s bone mineral density to a population of peers

Question 13

T/F: When ordering an x-ray following a minor musculoskeletal trauma in which fracture is suspected, one view is sufficient

Answer 13

False — one view is no view!

ALWAYS ORDER MULTIPLE VIEWS

Question 14

Is a greenstick fracture considered complete or incomplete?

Answer 14

Incomplete — some cortex is still intact

[to be considered complete, all parts of the cortex are disrupted]

Question 15

OLDACID is a mnemonic used to describe what is observed in X-ray. What does it stand for?

Answer 15

Open vs. Closed
Location
Degree of fracture
Articular extension/involvement
Comminution/pattern
Intrinsic bone quality
Displacement/angulation/rotation

Question 16

_______ = fracture through the epiphyseal plate

Answer 16

Salter-Harris

Question 17

5 classifications of Salter-Harris fractures using SALTER mnemonic

Answer 17

Type I: Straight across

Type II: Above

Type III: Lower (beLow)

Type IV: Two or through

Type V: ERasure fo growth plate or cRush

Question 18

Condition where bone tissue forms inside muscle or other soft tissue after an injury; tends to develop in young adults and athletes who are more likely to experience traumatic injuries

Answer 18

Myositis ossificans

Question 19

4 benign bone tumors

Answer 19

Giant cell tumor
Osteochondroma
Osteoblastoma
Osteoid osteoma

Question 20

3 malignant bone tumors

Answer 20

Chondrosarcoma
Osteosarcoma
Ewing sarcoma

Question 21

Benign, but locally aggressive and destructive bone tumor composed of multinucleate osteoclast-type cells; usually solitary and seen in 20s-40s at the epiphyseal end of long bones, typically around the knee and have “soap bubble” appearance on X-ray

Answer 21

Giant cell tumor

Question 22

Giant cell tumors most commonly affect the ______ part of long bones, usually around the _____ joint.

They often cause ______-like symptoms but pts may present with pathologic fractures. They have _________-appearance on X-ray

Answer 22

Epiphyseal; knee

Arthritis; soap-bubble

Question 23

Most common benign bone tumor; most commonly solitary and seen in men and diagnosed in late adolescence through early adulthood; commonly pedunculated and between 1-20 cm, arising from metaphysis of long tubular bones, particularly around the knee

Answer 23

Osteochondroma

Question 24

Clinical presentation of osteochondroma

Answer 24

Frequently diagnosed incidentaly, but may present as a slow-growing mass which can be painful if it impinges a nerve or if the stalk is fractured

Question 25

Osteochondromas most commonly arise from the ______ of long bones, particularly around the ____ joint

Answer 25

Metaphysis; knee

Question 26

What is the difference between osteoid osteoma and osteoblastoma in terms of size, site of origin, presentation, and ASA responsiveness?

Answer 26

Osteoid osteomas are <2cm, originate in appendicular skeleton, and present with severe nocturnal pain that is relieved by ASA and other NSAIDs

Osteoblastomas are >2cm, originate in posterior spine, and present with chronic pain that is unresponsive to ASA

Question 27

Malignant cartilage-producing tumor most commonly seen in men who are in their 40s or older; most commonly in axial skeleton (pelvis, ribs, shoulder), and presents as painful, progressively enlarging mass

Answer 27

Chondrosarcoma

Question 28

Malignant osteoid matrix-producing bone tumor that is the most common primary malignant tumor of bone; bimodal age distribution in <20 and again in older adults. Most commonly arise from metaphysis of long bones of extremities (often the knee). Presents as painful, progressively enlarging mass

Answer 28

Osteosarcoma

Question 29

Osteosarcomas most commonly arise from the _____ of long bones of the extremities.

They are associated with mutations in ____ and ____.

They have a _______ pattern and ______ _______ on plain film

Answer 29

Metaphysis

RB; TP53

“Sunburst”; “Codman Triangle”

Question 30

Malignant, primitive neuroectodermal tumor commonly arising from diaphysis of long bones (femur) and flat bones of the pelvis in white males <20 y/o; presents as painful enlarging mass with affected site often being warm, swollen, and tender

Answer 30

Ewing sarcoma

Question 31

Ewing sarcoma commonly arises from the _____ of long bones like the femur, and the flat bones of the pelvis.

It is associated with a ______ translocation, CD-99 positivity, and a _______ appearance on plain film

Answer 31

Diaphysis

(11;22); “Onion skin”

Question 32

3 pathways for organisms to reach bone

Answer 32

1. Hematogenous spread
2. Extension from a contiguous site
3. Direct implantation (trauma or surgery)

Question 33

Most common cause of pyogenic osteomyelitis

Answer 33

Staph aureus

Question 34

Etiology of osteomyelitis to consider in an IV drug user

Answer 34

Staph aureus

Question 35

3 etiologies of osteomyelitis to consider in UTI-associated osteomyelitis

Answer 35

E.coli

Pseudomonas

Klebsiella

Question 36

2 etiologies to consider with osteomyelitis in neonates

Answer 36

H.influenzae

Group B strep

Question 37

Etiology of osteomyelitis to consider in pt with sickle cell disease

Answer 37

Salmonella

Question 38

Etiology of osteomyelitis to consider in sexually active young adults

Answer 38

N.gonorrhea

Question 39

Describe progression of hematogenous osteomyelitis to sequestra (separation of dead bone)

Answer 39

Inflammatory exudate within marrow —> increased intramedullary pressure —> extension of exudate into cortex —> rupture of periosteum —> interruption of periosteal blood supply —> necrosis —> sequestra

Question 40

What is the imaging modality of choice for <2 weeks of symptoms + suggestive clinical history of osteomyelitis?

Answer 40

X-ray, followed by MRI if it looks like osteomyelitis

[if symptoms have been going on >2 weeks, do MRI right away]

Question 41

What bone disease is characterized by function-limiting pain, effect on walking distances, pain at night or rest, activity induced swelling, stiffness, mechanical issues like instability, locking, and catching?

Answer 41

Osteoarthritis

Question 42

Radiographic evidence of osteoarthritis

Answer 42

Joint space narrowing
Osteophytes
Eburnation of bone
Subchondral sclerosis
Subchondral cysts

Question 43

What bone disease is characterized by morning stiffness >1h, swelling in >3 joints, nodules, bony erosions and decalcification, symmetric arthritis, and often affects MCP, PIP, and wrist?

Answer 43

Rheumatoid arthritis

Question 44

Rheumatoid arthritis appearance on radiographs vs. MRI

Answer 44

Radiographs show periarticular erosions

MRI shows soft tissue inflammation and pannus

Question 45

Clinical manifestations of rheumatoid arthritis are similar to arthralgia secondary to _______ infection, except in the latter: symptoms usually last no more than 1-2 weeks, and patients may present with fever and other systemic findings

Answer 45

Parvovirus

Question 46

T scores associated with osteopenia vs. osteoporosis

Answer 46

Osteopenia = L2-4 lumbar density of 1.0-2.5 standard deviations below the peak bone mass of a 25 year old individual (T score of -1 to -2.5)

Osteoporosis = L2-4 lumbar density >2.5 standard deviations below the peak bone mass of a 25 year old individual (T score < -2.5)

Question 47

What bone disease may present with arthritis in the hands, dactylitis, onychodystrophy, onycholysis, chronic uveitis, entheses such as achilles tendonitis, posterior tibial tendonitis, and plantar fascitis in the setting of rash on extensor surfaces?

Answer 47

Psoriatic arthritis

Question 48

Radiographic hallmark of psoriatic arthritis

Answer 48

Pencil-in-cup deformity

Question 49

Bone disease caused by imbalance of osteoblastic and osteoclastic activity, causing an increase in disordered and structurally unsound bone mass; presents with elevated alkaline phosphatase with normal calcium and phosphorus, and mosaic pattern of lamellar bone on histology

Answer 49

Paget disease

Question 50

In terms of imaging when paget disease is suspected, _______ can be diagnostic, while ________ is useful for staging

Answer 50

X-ray; Radionuclide bone scan

Question 51

What are 2 long term complications of paget disease?

Answer 51

High-output heart failure secondary to AV shunts

Increased risk of osteosarcoma

Question 52

Untreated, symptomatic hyperparathyroidism can lead to what 3 bone pathologies?

Answer 52

Osteoporosis

Brown tumors

Osteitis fibrosa cystica

Question 53

What bone disease presents with bone pain and plain film findings including subperiosteal bone resorption on radial aspect of middle phalanges, tapering of distal clavicles, “salt and pepper” appearance of the skull, bone cysts, and brown tumors of the long bones?

Answer 53

Osteitis fibrosa cystica

Question 54

Group of diseases characterized by a reduction of bone resorption and diffuse, symmetric skeletal sclerosis secondary to impaired osteoclasts; most commonly due to carbonic anhydrase II mutation. Pts may be asymptomatic or present with fracture, pancytopenia, or extramedullary hematopoiesis

Answer 54

Osteopetrosis