MSS05 Introduction To Radiology Of The Musculoskeletal System Flashcards
1
Q
Imaging modalities
A
- Radiography
- CT
- Ultrasound
- MRI
- Radionuclide / Nuclear scan
2
Q
Anatomy of joint
A
- Bone
- Joint: >=2 articulating bone surfaces, cartilage, capsule, synovium (if synovial joint)
- Soft tissues:
- muscle
- tendon (muscle to bone)
- ligament (bone to bone)
- bursa (cushion between bones and tendons and/or muscles around a joint)
3
Q
Radiography advantages / disadvantages
A
Advantages:
- readily available
- ***cheap
- ***good bone and joint details esp. for appendicular skeleton (able to see dislocation)
- best modality / most cost-effective for ***simple fracture
Disadvantages:
- ***ionising radiation (very low dose)
- limited ***soft tissue visualisation and differentiation (synovium, muscle, cartilage, tendon, ligament all similar)
- not so good for ***complex anatomy / pathology
4
Q
Radiography application
A
- Trauma (fracture)
- Bone tumours (classification and diagnosis)
- Infection and inflammation (bone/joint involvement: osteomyelitis, arthritis)
- Spinal column pathology (scoliosis, degeneration but NO neural / disc details)
5
Q
Computed tomography
A
***X-ray beam rotating around patient
—> data acquired in single slice / single volume
2 types:
- Helical scanning (1 source 1 detector)
—> continuous gantry rotation + table motion
—> helical path of x-ray beam around patient
—> no waiting between slices to move table
- Multi-slice helical reconstruction (multiple detectors)
—> produce a set of interleaved helices
6
Q
Advances in CT technology
A
- Faster scanning time
- less patient motion artefact
- faster anatomical coverage and speed - Sub-mm coverage
- smallest details can be scanned within practicable scan times - Software advances to improve image quality
- smoother multiplanar + 3D reconstruction
- artefact reduction algorithm
7
Q
CT advantages and disadvantages
A
Advantages:
- excellent for **bone details particularly in **complex region (e.g. pelvis)
- detection of subtle ***soft tissue calcification
- capable of reconstruction into ***different planes (e.g. sagittal / coronal)
- guide aspiration in ***deeply-situated lesion
Disadvantages:
- ionising radiation higher
- expensive
- NOT as good as MRI / ultrasound for soft tissue differentiation
8
Q
CT application
A
- Trauma in **complex area / pathology
- severe trauma affecting multiple areas of body
—> minimal mobilisation of patient
—> fast / **one stop investigation for multiple system
—> prioritise management e.g. vascular injury
- excellent for excluding cervical spine injury
—> esp. when radiographs are equivocal / inadequate (cervicothoracic junction not included on plain film) - Tumour
- guide biopsy
- better definition of **bony details + detection of **fine calcification (adjunct to plain radiography) - Infection and inflammation
- **deep seated abscess (e.g. psoas abscess) and drainage
- **rarely used in arthropathy (good for associated lung pathology) - Spinal column and canal pathology (ONLY if MRI contraindicated e.g. pacemaker, guide nerve root block)
9
Q
High resolution Ultrasound (HRUS)
A
- Linear transducer 5-12 MHz (resolution 0.1mm)
- Excellent ***superficial soft tissue details
- ultra-sound cannot penetrate dense structures e.g. bones —> no signal
10
Q
Ultrasound advantages and disadvantages
A
Advantages:
- no ionising radiation
- cheap
- good for ***superficial structures and masses
- ***real-time examination —> see movements
- excellent spatial resolution particularly in superficial joints (0.1mm)
Disadvantages:
- operator dependent
- ***long learning curve
- ***limited depth of penetration of sound beam —> poor delineation of large / deep masses
- cannot see through bone (can only see bony cortical surface)
11
Q
Ultrasound application
A
- Confirm presence / absence of mass
- Superficial soft tissue pathology
- **cystic vs non-cystic masses
- give specific diagnoses in some masses e.g. neurogenic tumour, lipoma
- **effusion vs synovial thickening - Real-time examination of joint / tendons
- ***Real-time guidance for aspiration / biopsy of superficial soft tissues
12
Q
Magnetic Resonance Imaging
A
- strong magnetic field
—> ***NO pacemakers, metallic implants, neurostimulators
Imaging sequences:
- **T-1 weighted —> see **fat
- T-2 weighted with fat suppression —> see **fluid (記: H*2O)
- Proton-density with fat suppression (look at finer structures e.g. ligaments)
13
Q
MRI advantages and disadvantages
A
Advantages:
- ***no ionising radiation
- multiplanar capability
- ***excellent soft tissue differentiation
- sensitive to ***bone marrow changes (~ Nuclear scan), but not so good for cortical bone
- modality of choice for ***spinal and epidural lesions
Disadvantages:
- not readily available —> long waiting time —> reserved for urgent cases
- ***VERY expensive
- ***contraindicated in patient with pacemaker / electronic devices
14
Q
MRI applications
A
- Trauma
- rarely used for bone fractures
- occasionally in suspected undisplaced trabecular fracture
- soft tissue / ligamentous injuries e.g. knee, shoulder, ankle
- **spinal trauma with cord / neural damage
—> e.g. cord impingement / oedema
—> **inflammation in soft tissues / ligaments (only MRI can tell, CT cannot)
- detect marrow oedema in occult undisplaced fracture - Tumour
- staging (NOT for diagnosis)
- choosing biopsy site (MRI performed before biopsy) - Infection and inflammation
- osteomyelitis, myositis, arthritis, tenosynovitis, cellulitis - ***Spinal column and canal pathology
- disc protrusion, spondylodiscitis, spinal cord / nerve compression
15
Q
Radionuclide / nuclear scan
A
Inject patient with radionuclide (***Technetium-99M MDP)
—> localises to areas of pathology
—> detector to retrieve image
Bone scan:
—> very sensitive for **marrow changes but **not specific (tumour, infection, and fracture may look similar)
Specialised scans:
—> e.g. WBC / gallium scan for localisation of abscess / infection
Positron emission tomography (PET)
—> combined with CT
—> PET-CT
