Imaging of Muscles Flashcards
Why Image muscle?
- Neurology perspective
- Visualisation of muscle involvement in neuro-muscular disorders - Broad clinical perspective
- Traumatic injury to musculature
- Identification of muscle masses and neoplasms - Research perspective
- Better understand pathological processes in myopathies and neuropathies
- Identify ‘biomarkers’ of disease - Non-invasive (cf EMG; biopsy)
- No ionising radiation (if MRI used)
- Progression/response to treatment
What are the advantages for imaging muscles?
- Investigation of inherited neuromuscular disorders
- Clinical syndromes similar
- Overlap of histopathological features
- Selective muscle involvement on imaging
When do we image the muscles?
- Are the muscles normal?
- Characterisation of muscle changes
- Myopathic vs neurogenic
- Symmetry; proximal vs distal; muscles involved
- Fatty change vs water deposition - Identify potential site for biopsy
- Progression/ response to treatment
- Specific pattern of involvement
- Reduces list of candidate genes
- Clinical syndrome must be clearly defined - Mutation found on gene testing? Pathogenic
What are used to image muscles?
- Ultrasound
- CT
- MRI
- Technical factors
- Sequences
- Axial slices most useful
When is CT usd?
Usually only if MRI is contra-indicated
What is MRI
- Most widely adopted modality
- Excellent soft tissue contrast
- Sensitive to pathological changes (fat, fluid)
What are the technical factors?
- Patient supine
2. Surface phased array coil
What are the sequenceS?
- T1w (fatty infiltration)
- T2w with fat suppression (water deposition)
- +/- DWI; post-gadolinium T1w
What is T1w and T2w sensitive to?
- T1w is sensitive to fat infiltration
2. T2w is sensitive to water
How can you see if there is any fat infiltration or water deposition?
Only use T1w with no fat suppression and T2w with fat suppression
What to look for in muscles?
• Distinguish between anterior compartment involvement vs posterior compartment involvement
• Very few conditions just affect medial compartment
• Fatty change (‘’infiltration’’)
- Increased signal on T1w images
- Long term consequence of muscle pathology
• Water deposition (‘’inflammation/oedema’’)
- Increased signal on T2w images
- Indicates ‘active’ muscle pathology
• Fibrosis
- Reduced signal on T1w and T2w images
Why is muscle imaging difficult?
Related to age and activity
