Alternative Imagine Modalities

Question 1

What are other Modalities?

Answer 1

• MRI (Magnetic Resonance Imaging)
• Ultrasound
• Nuclear Medicine (radio-isotope scanning)
• Combination of modalities including PET.

Question 2

What are the Advantages of CT?

Answer 2

• Images bone and soft tissue
• Differentiate different tissues
• Head injury – can see bone and brain
• Speed (compared MRI)
• Multi-planar (manipulate, reconstruct images)
• Cost and availability usually cheaper (compared with MRI)

Question 3

What are the Disadvantages of CT?

Answer 3

• Patient Radiation Dose
• Dose for head ~2 mSv
• Often requires intravenous contrast to distinguish tissues (iodine based, allergy)
• Artefact (metallic objects, amalgam in head and neck)
• Expensive in comparison with plain radiography

Question 4

What is an MRI good for?

Answer 4

Good for looking at soft tissue

Cortical bone and dental hard tissue always black – not much water present

Various sequences show different tissue as bright/dark

T1 weighted – water dark

T2 weighted – water bright

Generally, T1 for anatomy, T2 for pathology

Question 5

What are the advantages of MRI?

Answer 5

• No ionising radiation
• Excellent for viewing soft tissue
  
  • also cancellous bone:-
  • changes in marrow, infection, infiltration
  • cortex breach
• Multi-planar

Question 6

What are the Uses of Ultrasound?

Answer 6

Neck Swelling:

Tissue of origin

Solid/cystic

Characteristics (benign/malignant)

Salivary glands:

Intra-glandular lesions

Neoplasm

Sjogrens syndrome

HIV

Calculi within the salivary glands and ducts

Blood flow:

Carotid artery disease

Relationship to lesion and lesion supply

Guidance for biopsy/drainage