What are the different types of bone imaging modalities?
1) X-Rays
2) Ultrasound (US)
3) Computed Tomography (CT)
4) Magnetic Resonance Imaging (MRI)
5) Nuclear Medicine
What conditions can be seen in imaging?
1) Trauma
2) Tumour
3) Infection & Inflammation
4) Degeneration
How do X-RAYS work?
What are the advantages and disadvantages?
How much of bone loss is required to be visible on an X-Ray?
Release IR -> hits an atom -> electron knocked out -> atom becomes ion
- results in unatural chemical reaction in cells
- Breaks DNA strand
= DNA dies -> disease
= DNA mutates -> cancer
= DNA mutates in gametes -> birth defects
Free electron collides with other atoms to make more ions
ADVANTAGES
- Cheap
- Bony anatomy
- Trauma
DISADVANTAGES
- IR
- Soft tissue restricted
- Limited for other diseases
- 50% bone loss
How is IR measured?
Sieverts (Sv)
Why, and what makes an X-Ray white, grey, and black?
WHITE -> absorbs the most X-Ray
- Bone
GREY -> radiolucent
- Tumour
- Abscess / pus
- Fluid / blood
- Muscle
BLACK -> absorbs the least X-Ray
- Air
What are causes of BONE LOSS?
1) Osteoporosis
2) Healing fracture
3) Secondary tumours -> aggressive osteolysis
4) Infection -> osteomyelitis (Brodie’s abscess), diabetes
What are causes of BONE GAIN (increased bone density)?
1) OA -> sclerosis
2) Healing fractures
3) Infection -> osteomyelitis ( healing Brodie’s abscess)
4) Osteoblastic tumours -> breast cancer
What is Wolff’s Law?
Trabecular bone is under two types of pressures:
1) Compressive pressure
2) Tensive pressure
Wolff’s law states that the trabecular bone is able to adapt to the load that it is under, i.e. higher load= remodel to resist higher load
How does CT work?
What are the advantages and disadvantages of CT?
Several X-Rays and computer processing to give cross-sectional images.
ADVANTAGES
- Bony anatomy
- 3D -> multiplanar reformats
DISADVANATGES
- Expensive
- Higher dose of IR (1 lumbar CT= 500 CXR)
- Soft tissue limited
How does MRI work?
What are the advantages and disadvantages of MRI?
Distribution of protons is based on water and fat -> creates detailed imaged of soft tissue structures
ADVANTAGES - Discriminates soft tissue = tumours = inflammation = degeneration
DISADVANTAGES
- Expensive
- Contraindications
- Claustrophobia
How does US work?
What are the advantages and disadvantages of US?
High frequency sound waves to examine internal organs
ADVANTAGES
- Cheap
- No IR
- Superficial anatomy
- Tissue elasticity interfaces
- Doppler US -> vascularity
DISADVANTAGES
How does NUCLEAR MEDICINE work?
What the advantages and disadvantages of nuclear medicine?
1) Give radioactive tracer to patient
2) Detect radiation digitally
ADVANTAGES
- Cheap
- Sensitive
DISADVANTGES
- IR
- not specific
What NOT to X-Ray?
1) Ribcage
- except to rule out pneumothorax (breathlessness, shallow breaths, and pleuritic chest pain)
2) Nasal bone
- only lateral view
3) Coccyx
- highly variable in shape (coccygeal disc)
- large dose of radiation
What are the 4 rules of an X-Ray?
1) Two views min, perpendicular to one another (AP, and lateral)
What are the radiological signs of a fracture?
1) Cortex breach
2) Sclerosis line
3) Lucent line
4) Disruption of trabeculae
5) Change in bony contour
ADDITIONAL non-bony signs
1) Haemarthrosis
2) Lipohaemoarthrosis (fat on top of effusion)
3) Soft tissue swelling
Under which circumstances does a lucent line result?
1) Fracture fragment are separated
2) Resorption of bone in fracture site
How is SOFT TISSUE SWELLING identified in an X-Ray?
- White = bone
- Light grey = water
- Dark grey = fat
- Black = air
NORMAL
Epidermis => light grey
Subcutaneous fat => dark grey (directly under epidermis)
SOFT TISSUE SWELLING
Subcutaneous fat is seen as light grey (merged with epidermis)
How is HAEMARTHROSIS identified on an X-Ray?
1) Elevated anterior fat pad
2) Visible posterior fat pad
3) Elbow effusion
How is LIPOHAEMARTHROSIS identified on an X-Ray?
Fat deposition (dark grey) on top of effusion (light grey)
What are the bony rings in our body?
1) Pelvis
- Obturator foramen X2
2) Paired long bone -> X-Ray joint above and below (one breaks, so does the other, or the ligament that connects the two rips)
- Forearm
- Leg
3) Vertebra
4) Mandible
- Temporomandibular joint
- Mandibular ramus (L and R)
5) Zygomatic arch
Why are hip fracture often not visible on X-Ray in elderly?
What are better alternatives?
- Osteoporotic and OA bone -> changes in bone texture
- Osteophytes -> misinterpreted as fractures
1) CT -> clearer
2) MRI -> better since it shows haemorrhaged and oedema associated with fractures
How do you describe a fractures?
1) Position - ADDIF
2) Path of the fracture line
- Transverse
- Oblique
- Spiral
- Longitudinal
3) Simple or comminuted?
4) Joint involvement? (yes= higher risk of OA)
5) Closed or open (open= risk of osteomyelitis)
POSITION Angulation (valgus/posterior, varus/anterior) Displacement (sideways) Distraction (away) Impaction (towards) Foreshortening
Describe a Colle’s fracture.
1) Angulation of epiphysis- dorsal
2) Impaction of epiphysis
3) Path - transverse fracture of distal radius
4) Simple
5) No joint involvement
6) Closed
Give examples of fractures in children.
1) Plastic
2) Greenstick <
3) Torus >
4) Growth plate fractures
5) NAI -> metaphysis corner fractures
