OrthoFracs Logo

Imaging Tumours

Principles

  • Imaging used for four aspects
    • Make the diagnosis
    • Stage the lesion
    • Plan the treatment
      • Staging
      • Biopsy
    • Assess the response

Enneking's Questions

  • What is the location of lesion?
  • What is the lesion doing to the bone?
  • What is the bone’s reaction to the lesion?
  • What is the tumour matrix?

Imaging Modalities

X-ray

  • Initial examination
  • Main-stay
    • Evaluation of
      • Location
      • Margin
      • Periosteal Reaction
      • Matrix

Bone Scan

  • Most lesions have ↑ uptake
  • Screening tool
  • Non-anatomical
  • False negative with
    • Inactive benign tumours
    • Myeloma
    • Eosinophilic Granuloma
    • Haemangioma
    • Melanoma
  • Crude indicator of extent of lesion & response to treatment
  • Main role is demonstration of multiple lesions

CT Scan

  • Best for assessing mineralization & bony details
  • Benign bone tumours
    • Violation of cortex
    • Matrix mineralization
  • Shows local extent of tumour
    • Intraosseous
    • Extension into soft tissue
  • Shows areas that plain XR visualize poorly
    • Spine
    • Pelvis

MRI

  • Best for assessing soft tissue
  • Very sensitive for
    • Soft tissue tumours
    • Soft tissue extension
    • Marrow involvement
    • Joint & Epiphyseal involvement
  • Shows relationship to neurovascular bundle well
  • May be oversensitive
    • Oedema (reactive zone) vs Tumour

Diagnosis

  • Mainstay is plain film
  • Other modalities contribute
    • CT Scan
      • Defines architecture of lesion
    • MRI Scan
      • Determines extent of disease (can be over-sensitive)
    • Bone Scan
      • Locates other lesions

Spread

  • MRI is best
    • Intramedullary spread
      • T1 sequence
        • T1 with Fat Suppression/ Inversion Recovery
    • Cortical breakthrough
      • T2 sequence
    • Soft tissue spread
      • T2 sequence
    • Relationship to vessels
      • T2 sequence

Metastases

  • Lungs
    • CXR – see mets >/= 1cm
    • CT Scan – see mets >/= 2mm
  • Bone
    • Bone scan

Radiological Diagnosis of Bone Tumours

Watt Criteria (1985)

  • 1. Solitary or Multiple?
    • Multiple lesions more likely to represent metastatic lesions or systemic disorder
    • Solitary more often primary tumour
  • 2. What type of bone involved?
    • Metastatic disease presents most in axial skeleton
    • Osteoid osteoma rarely in intramembranous bones
  • 3. Where is lesion in bone?
    • Fibrous cortical defect is cortical in location
    • Chondroblastoma epiphyseal
    • GCT is subarticular in mature skeleton
  • 4. Are margins well or ill defined?
    • Slow growing tumour has short zone of transition with normal bone
    • Aggressive tumours more permeative
  • 5. Is there a bony reaction?
    • More indolent the greater the sclerosis
  • 6. Does lesion contain calcification?
    • Useful signs of cartilage tumour
Bookmark and Share