Radiological Evaluation of Bone Tumors

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Radiologic examination to evaluate :
1. Pattern of Growth & bone destruction
2. Pattern of Matrix mineralization
3. Pattern of Cortical Involvement (tubular bone)
4. Pattern of Periosteal reaction
5. Location


X-ray 

 Pattern of Growth & bone destruction

 

  • Geographic pattern

     

     

     

     

     

    • Well circumscribed pattern of bone destruction with a sclerotic rim. The sclerotic rim is more commonly seen in the weight bearing bones and represents bone reaction to the lesion.
    • Its presence means that the bone has sufficient time to react.
    • Benign and non-growing (or extremely slowly growing) lesions
Growth-bon- destruction
  • Expansible growth pattern

     

     

     

     

     

    • Visible widening of the affected portion of bone
    • The more rapidly growing lesions may still show geographic pattern, but lack the sclerotic rim & may show cortical expansion. In many cases, an interrupted periosteal rim will surround the expanded portion of bone.
    • In locally aggressive tumors and in low-grade malignancies.
Expansible-growth-pattern
  • Permeative pattern

     

     

     

     

     

    • Tiny radiolucencies in between the residual bone trabeculae. Due to the minute size of radiolucencies the lesion may be difficult to see and to delineate on the plain film. Generally, the more rapidly growing a lesion, the more difficult it is to see on plain film.
    • In rapidly growing lesions .
permeative-pattern
  • Moth-eaten pattern

     

     

     

     

     

    • Ill-defined zone of multiple small radiolucencies that may coalesce.
    • Represents aggressive, infiltrative patterns of bone destruction.
    • In rapidly growing lesions.
moth-eaten

 

 Pattern of Matrix mineralization

Osteoid

  • Cloud-like or ill-defined amorphous densities with haphazard mineralization. This pattern is seen in malignant osteoid in osteosarcoma.
  • Mature osteoid, or organized bone, shows more orderly, trabecular pattern of ossification. This is characteristic of the benign bone-forming lesions such as osteoblastoma.
osteoid-matrix

Chondroid

  • It is usually easier to recognize cartilage as opposed to osteoid by the presence of focal stippled or flocculent densities, or in lobulated areas as rings or arcs of calcifications. They are best demonstrated by CT.
  • Whatever the pattern, it only suggests the histologic nature of the tissue (cartilage) but
    does not reliably differentiate between benign and malignant processes.
chondroid-matrix

Marrow and round

  • Pure osteolytic
pure-osteolytic

Fibrous

  • Ground glass (hazy, the appearance of view box plastic).
ground-glass-appearance

Cystic lesions

  • Soap bubbles appearance due to its fibrous septae
soap-bubble-appearance

 

Pattern of Cortical Involvement (tubular bone)

 

None: shape of lesion will be elongated

• Cortex acts as a "barrier" to lesion, which grows along path of least resistance through medullary canal. This pattern of involvement typically relates to a slow growing lesion

no-cortical-lesion

Endosteal scalloping

• The inner surface of the cortex is "eroded", but the cortex is still intact.

endosteal-scalloping

Expanded cortex

• Shell periosteal reaction. This lesion is slow growing, and over a long period of time there is "pressure atrophy" of the cortex endosteal surface

expanded-cortex

Break through cortex

• This usually indicates an extremely aggressive process, especially if the adjacent bone is ill- defined.

Break-through-cortex

Pressure atrophy from an adjacent soft tissue mass or tumor

  • A primary soft tissue mass/tumor located adjacent to a bone can cause bone lysis secondary to pressure atrophy.
Pressure-atrophy

 

Periosteal reaction

Focal cortical thickening

  • Solid periosteal reaction, or "buttress"
  • In slow- growing tumors
focal-cortical-thickening

Codman's triangle

  • Rapidly growing lesions penetrate through the cortex causing separation of the periosteum and formation of lamellated new bone. If the periosteum elevates to a significant degree, it can break forming an acute angle.
  • In malignant bone tumors and in some other rapidly growing lesions such as ABC, or in reactive processes (osteomyelitis, and subperiosteal hematoma).
  • Codman's triangle is usually free of tumor unless infiltrated through its open end or by transcortical growth.
codman-triangle

Speculated “hair-on-end"

  • in rapidly growing lesion.
speculated

Divergent spiculated "sunburst"

  • a sign of malignant osteoid production
  • highly suggestive of osteosarcoma
divergent-speculated

Onion-skinning

  • in response to a rapidly growing lesion.
onion-peel

 

Location Bone Tumor locations

general: single or multiple

if multiple locations in the foot/ankle, then the pathology is probably not a tumor process, unless metastasis from another primary tumor site.

which bone is affected?

some tumors have a predilection for a particular bone. Example:

  • phalanges and the enchondroma;
  • the calcaneus and the unicameral ( solitary) bone cyst; subungual exostoses. .

Position in a Long Bone

some tumors have a characteristic position in a tubular bone. In the transverse or longitudinal plane of the bone, Transverse: central, eccentric, cortical, or parosteal Longitudinal: epiphyseal, metaphyseal, metadiaphyseal, or diaphyseal

 


Bone Scan

Diphosphonates labelled with Technetium 99 usually used in dose of 500 – 600 mBq
Osteoid osteoma -> increased activity in blood pool phase as well as delayed bony phase
Inflammatory lesions also increased activity in blood pool scan
Gallium 67 has also been utilised

CT Scans

Indicates extent of bony involvement / destruction
Good for detecting subtle cortical disruption, fracture, calcification or ossification
Not as good as MRI for soft tissue extent. Can detect soft tissue masses >/= 5mm diam.
Useful to stage – eg. lung secondaries

Angiography

Feeding vessels identified as well as the tumour proximity to major vessels
Displacement of vessels by tumour -> access for excision of the tumour
Embolisation of vascular tumour prior to surgery
Intra-arterial chemotherapy

MRI

Good soft tissue definition (better than CT) and extra-osseous extension, joint involvement, skip lesions and epiphysial extension -> staging -> extent of tumour both intra and extra medullary
Able to image in any plane – thus good for pelvic/sacral lesions
T1 weighted images best for looking at extent of marrow involvement and T2 more useful for evaluating cortical bone and soft tissue extent (NB – CT better for showing areas of calcification / ossification)
Best technique to identify haemorrhage/oedema/inflammation- eg prior biopsy
Oedema usually surrounds malignant lesions & is unusual around benign tumours

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