Session 1 Lecture Radiology Flashcards
How does X-ray work
Projecting beam of electrons through an object onto an image detector
how does articular cartilage appear on X ray
Appears as joint space as radiolucent
What is a fracture
A complete or incomplete break in the continuity of bone
Transverse fracture
Break crosses bone at right angle to long axis (horizontal line break)
Linear or saggital plane fracture
Passes in parallel to long axis of bone (vertical line)
Oblique fracture
at oblique angle (diagonal)
Can be displaced or non displaced
Spiral fracture
Fracture line spirals round in multiple plains
Compression fracture
Cancellous bone when axial load compresses bone beyond limit (often lumbar vertebrae)
Bone is crushed-
Comminuted fracture
Bone broken in at least 2 places e.g. car accident
Greenstick fractures
Only occur in children- incomplete fractures where bone bends and cracks instead of breaking into separate pieces
Epiphyseal separation fractures
Only in children. Fracture line extends through an unfused growth plate, separating epiphysis from metaphysis
Define separate ossification centres in long bones
Primary- in diaphysis (shaft)
Secondary- in epiphyses (end)
Supported by growth plates/epiphyseal plates
Significant difference between a child’s bone age and chronological age may indicate
Early or delayed puberty, growth hormone deficiency, hypo/hyperthyroidism, or malnutrition
8 Stages of fracture healing
- Haematoma formation
- Tissue death
- Inflammation
- Angiogenesis
- Soft callus formation
- Hard callus formation
- Lamellar bone
- Remodelling
3 phases of fracture healing
- Inflammatory phase (hours to days): haematoma formation, tissue death, inflammation
- Reparative phase (days to weeks): Angiogenesis, soft and hard callus formation (soft callus looks fluffy)
- Remodelling phase (months to years): lamellar bone and remodelling. Radio graphic union occurs where fracture line completely obscured
CT scanning key features
Narrow X ray beams to produce slices of an object, create 2D and 3D images
CT scanning limitations
- If a patient moves, motion artefact distorts image
- makes interpretation difficult
- Exposure to higher radiation dose
- Severely obese patients may not always fit
- Can be allergic to contrast even anaphylaxis
How do air fat and water appear on CT scan
Black
How do soft tissues and boneappear on CT scan
Grey and white respectively
MRI key features
- Doesn’t use radiation
- Strong magnet generates a magnetic field
- Protons in hydrogen atoms line up
- Radiofrequency signal pulses deflect protons
- Pulse terminated, protons realign, emit signal
- Signal detected and 3D image created
Pros and cons of MRI
- Better than CT and X-ray for imaging soft tissues
- Poor at showing micro-architecture of bone
- No radiation
- Can’t have metalwork
- Noisy
- Imaging time longer
Different weightings of MRI
T1- fat is bright, fluid dark
T2- fat and fluid and bright
STIR- signal from fat suppressed so it appears dark, whilst fluid appears bright
Ultrasonography key points
- High frequency around waves to produce images
- Produced by transducer
- Non invasive and no radiation
- Can show non ossified structures
Cons of ultrasound
- Highly dependent on a skilled operator for interpretation of images
- Resolution of deep tissues is poor
- Limited suitability for bone and intra-articular imaging
Nuclear medicine key points
- Radioisotope labelled, biologically active drugs
- Marker of biological activity
- Assess areas of metabolically active bone e.g. in metastases
- Ionising hence DNA damage