Musculoskeletal #27

53-year-old female:

– Chronic sensory polyneuropathy (autoimmune). Long-term corticosteroid therapy.
Forefoot pain for three weeks (acute onset without trauma).
– Physical examination: no haematoma , mild swelling.
X-ray performed on day 2 after initial pain.
MRI performed on day 25 after initial pain.

What are the findings?

X-Ray: No obvious fracture.

MRI:
– Bone marrow heterogeneous oedema within the third metatarsal diaphysis (hypointense on T1W image, hyperintense on Proton Density (PD) FatSat image).
Linear low signal intensity fracture identified in all sequences.
Periosteal reaction due to callus formation. Periosteal thickening and enhancement (contrast administration is not necessary for diagnosis).
– Surrounding soft-tissue oedema (adjacent fat and interosseous muscles).

Metatarsal stress fracture (“march fracture”)

– Stress fractures are caused by overuse and repetitive activity.
– Everyday activities may result in a stress fracture if there is any disease or therapy that weakens the bone such as osteoporosis or long-term use of steroids (bone insufficiency: long-term treatment with steroids in this case).
– Classically affects the 2nd or 3rd metatarsal of the foot “march fracture”: named after its prevalence in soldiers who often undertake repeated and prolonged periods of walking as part of their training or work.
– Bone changes are usually not evident on X-rays before 10 to 21 days following the injury. May not be visible for several weeks later, until callus bone formation (the sensitivity range, for detecting stress fractures on initial examinations, is 15-35%; it increases to 30-70% at follow-up studies due to bone reaction).

MRI findings:
– The fluid-sensitive sequences (T2-weighted images with chemically selective fat suppression or STIR sequences) are very useful for the detection of the earliest changes of stress reaction, such as periosteal reaction, muscle, or bone marrow oedema.
– T1-weighted sequences depict the anatomy and more advanced stress-related findings.

Grading based on MRI (Arendt and Griffiths)🙂
1: Mild – moderate periosteal oedema on STIR, no marrow changes.
2: Moderate – severe periosteal oedema on STIR + marrow changes on T2-weighted.
3: Grade 2+ marrow changes on T1-weighted.
4: Fracture line visible.

Musculoskeletal #26

Describe the abnormality

Bilateral sacroiliac joint space narrowing, subchondral erosions, subchondral sclerosis, and subchondral fatty marrow infiltration.

What is the differential diagnosis?

Bilateral symmetrical:
Ankylosing spondylitis
Inflammatory bowel disease. 

Bilateral asymmetrical:
Psoriasis
Reactive arthritis (Reiter syndrome) 

What is the most likely diagnosis?

Ankylosing spondylitis

What are the markers of active inflammation?

Erosions with high signal intensity on STIR or T2- weighted images, subchondral edema, and enhancement within or adjacent to the sacroiliac joint.

What are the markers of chronic disease?

Low signal intensity on T1- and T2- weighted images, subchondral sclerosis, narrowing of the joint spaces, bone bridging, and ankylosis.

Musculoskeletal #24

48-year-old male:
– Heavy smoker
– Depressive syndrome

Found lying unconscious at home, in lateral position (opioid overdose)
Erythema and limited movement of the left shoulder
Blood test: CK 7949 u/l. Negative blood and aspiration cultures (no infection)

What do you see?

Findings

CT: Low attenuation area involving the posterior aspect of the deltoid muscle and the lateral aspect of the pectoralis major muscle. Superficial and deep fascia edema. No enhancing walls neither gas is seen.

MRI: Postcontrast T1FS images show hypointense unenhancing central muscle fibers surrounded by thick rim enhancement involving the posterior deltoid, teres minor, and pectoralis major muscles . Thickened and hyperenhancing adjacent fascia and reactive muscle edema are also noted.

What is the most likely diagnosis?

Rhabdomyolysis (type 2: myonecrosis)
– Injury to skeletal muscle that involves leakage of large quantities of potentially toxic substances into plasma.
– Type 1: homogeneous signal changes and contrast enhancement. Ischemic or reversible ischemic reaction.
– Type 2: homogeneous or heterogeneous signal changes and rim enhancement. Irreversible muscular necrosis (myonecrosis).

– Deep tissue injury: severe pressure ulcer, characterized by necrotic tissue mass under intact skin.

– CK > 1000 – 5000 iu/l “cut-off”.

– Risk factors: postoperative patients (position), obesity, male gender, diabetes, surgical bleeding…

Musculoskeletal #23

89-year-old patient with groin mass

What do you see?

Imaging Findings

Agressive isquion mass with bone destruction, soft tissue component, necrosis and osteid matrix.

In the staging CT: Vertebral and skull signs of paget disease (Bone marrow heterogenity with lytic and sclerotic foci, cortical thikening and bone expansion; as well as partial pagetiic spinal block)

What is the most likely diagnosis?

Diagnosis

Pagetic secondary osteosarcoma on a patient with polyostotic bone paget.

Teaching Points

Osteosarcoma hallmarks are agressive bone mass with osteoid matriz.It can be primary or secondary (mainly on pagetic or radiated bone)
.

Musculoskeletal #22

What do you see?

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Vertebral hemangioma with thickened trabeculae and fat foci inside the lesion, without soft tissue component with an associated pathological fracture.

TEACHING POINTS:
Bone hemangiomas are very frequent, atypical presentations and complications (like in this cases with soft tissue component and pathological fracture) are rare but radiologist must be aware of them to be able to make the correct diagnosis.

Musculoskeletal #21

65-year-old man. Paraplegia after skiing accident. What do you see?

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Imaging findings

Complete low dorsal transdiskal and transvertebral fracture with extension to middle and posterior columns on an ankylosed spine.
Sever posterior angulation and displacement of the superior segment cord deformity, compression and myelopathy.

Diagnosis

Severe complete unstable ankylosed spine fracture with cord compression and mielopathy

Teaching points

Ankylosed spine show specific patterns of fracture with: higher tendency to three column involvement, and increased frequency of neurologic complications.

Musculoskeletal #20

72-year-old alcoholic patient with intractable dorsal pain and legs numbness and weakness.

What do you see?

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IMAGING FINDINGS:

Thoracic spine compression fracture with posterior displacement of the posterior wall of the vertebral body compromising the spinal canal, cord compression and associated myelopathy. T2W image shows fluid and hypointense bubble-like artifact consistent with vacuum cleft in the collapsed anterior vertebral body

DIAGNOSIS:

Kümmel disease (osteonecrosis and collapse of the vertebral body)

TEACHING POINTS:

Intravertebral vacuum cleft and fluid within the collapsed vertebral body is a characteristic feature
Differential diagnosis includes a pathologic (tumoral) fracture, and the presence of air strongly favors osteonecrosis

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MR T2-weighted and CT images to highlight the characteristic features of Kümmel disease

Intravertebral fluid seen on T2 image and air on CT image

Musculoskeletal #18 – Flashcard

27-year-old patient with neurofibromatosis-type 1 (NF-1). Bone lesions found on PET-CT

What are the imaging findings?

Multiple bilateral multiloculated eccentric metaphyseal lucent lesions with thin sclerotic rim

What is the most likely diagnosis?

Multiple non-ossifying fibromas in a patient with NF-1

Teaching points

Very common benign lesion in young adults. Tend to heal or involute. Vast majority asymptomatic. Large lesions may be painful or weaken the cortical predisposing to pathological fracture (rare). Multiple in NF-1