Imaging MSK Flashcards
When is MRI used (3 clinical questions)?
Clinical question:
1 ligamentous/tendon tear?
2 muscle abnormalities?
3 internal composition of malignant tumour
CT interpretation steps (2)
1 cortex and bony trabeculae
2 joint alignment
What does US assess?
Soft tissues! assess before MRI
What does a doppler US assess?
Vessels
What suggests benign vs malignant masses on CT?
Benign: fat containing mass
Malignant: soft tissue masses
X ray of spine: multiple myeloma assessment?
1 sagittal alignment of spine (normal lumbar lordosis)
- abnormal thoraco-lumbar vertebrae (height - suggest #)
- metabolically weak (osteoporosis)?
- or underlying lesion inside bone causing weakness (haematalogical malignancies or metastases)
2 skull lesions (multiple scattered)
- suggests pathological lesions throughout body
- DDX: multiple myeloma but also could be metastatic process
3 image other aspects of the body
- multiple lesions throughout most of skeleton = diffusely infiltrative malignancy = multiple myeloma
4 axial thoracic spine
- multiple lytic lesions
- destruction of trabeculae with lytic/lucent appearance
- trace cortex = irregular and discontinuous
2 sequences of MRI imaging and explain difference
1 T1 weighted
- anatomical sequence
- fluid = black
- fat = white
2 T2 weighted
- edema/inflammation
- fluid = white
- blood vessels = black (fluid moving quickly)
Why does US allow us to perform biopsies?
US is real time
X-ray interpretation steps (4)
1 cortex
2 joint space
3 joint alignment
4 soft tissues (knee: supra patellar region!)
What measurement is used in CT?
Hounsfield Unit:
bone = white
air = black
What modalities are used to image MSK? (6)
1 X-rays: bones (and soft tissues)
2 CT: bones (better spatial resolution than MRI) and soft tissue
3 MRI: soft tissues (better resolution than CT), bones (marrow and extra osseus ST components) - no radiation but ensure no metal clips or pacing wires
4 US: soft tissues.
Real time, high resolution, no radiation. Anatomical and physiological information.
5+6 Fluoroscopy and angiography: real time x rays to get anatomical and physiological information. Also guides surgery – allows minimally invasive procedures.
Spinal MRI steps (4)
1 spinal alignment
2 individual vertebrae
3 vertebral discs
4 adjacent structures (spinal cord/spinal canal)
Key points multiple myeloma:
1 X ray
2 CT
3 MRI
4 Bone scan
1 lytic bone lesions, pathological #’s and 40% bone destruction needed
2 improved sensitivity and specificity, assess lesions and #’s, extra medullary lesions
3 more sensitive than CT, used to assess complications - neurologic
4 bone scan - limited utility
DDX of:
1 multiple focal lesions
2 diffuse osteopenia
3 compression fractures
1 metastases, leukaemia, primary lymphoma of bone
2 leukaemia, primary osteoporosis
3 osteoporosis, physiological wedging, trauma
