Wrist Imaging Flashcards
(28 cards)
Wrist exposure factors and rationale
55 kVp - high image contrast (large attentuation difference), small anatomical area = less kV, however more than hand
100 mA - fine focus for image detail,
0.04 s - provides required 4 mAs,
**No grid ** - no scatter
variations
- larger wrist = more kVp
- presence of disease = lower kVp
- inability to keep still = adjust exposure time and mA
- paediatrics = lower kVp
Standard wrist Projections
PA
- arm flexed at elbow, wrist internally rotated to pronate wrist
- radial and ulnar styloid process equidistant
- centre midway between radial and ulnar styloid processes
- collimate proximal 1/3 of metacarpals, carpals, distal 1/3 of radius and ulna, soft tissues
**Lateral **
- externally rotated 90 degrees from PA position
- radius and ulna superimposed vertically
- centre over radial styloid processes
- collimate proximal 1/3 of metacarpals, carpals, distal 1/3 of radius and ulna, soft tissues
External Oblique
- wrist externally rotated 45 degrees from PA position
- supported by radiolucent pad
- centre midway btw radius and ulna
- collimate proximal 1/3 of metacarpals, carpals, distal 1/3 of radius and ulna, soft tissues
Scaphoid projections
PA with Ulnar Deviation
- same as PA for wrist
- hand adducted towards ulnar (pinky)
- centre midway between ulnar and radius
- collimate scaphoid, trapezium, trapezoid, lunate, first metacarpal joint, radiocarpal joint
**PA with cranial angulation and ulnar deviation
**- same as PA scaphoid w ulnar deviation
- snuffbox is centre of IR
- angle beam 20 degrees to head
- collimate scaphoid and surrounding joints
Colles Fracture
fracture to distal radius with posterior displacement to fragment, FOOSH (falling on an outstretched hand)
What projections for Colles Fracture? Explain rationale for each
PA - standard projection to view wrist anatomy
Horziontal beam lateral - usually severe, so horizontal to avoid movement, more comfortable, to asses the severity of posterior displacement
Radiographic appearance of Colles Fracture
- posterior displacement of fracture in the distal radius
- soft tissue swelling
- dinner fork deformity
Smith’s Fracture
fracture to distal radius with anterior displacement of the fragment, falling on the back of the hand
What projections for Smith’s Fracture? Explain rationale for each
PA - standard projection to visualise wrist anatomy
Horizontal beam lateral - avoid movement of fracture, assess anterior displacement of radius
Radiographic appearance of Smith’s Fracture
- anterior displacement of fracture in the distal radius
- reverse dinner fork deformity
- soft tissue swelling
Greenstick/Torus Fracture
greenstick - when one cortex breaks, but the other doesn’t (bent on one side and fractured on other) and only occurs in children
torus - compression deformity, no fracture (buckled)
What projections for Greenstick/Torus Fracture? Explain rationale for each
**PA **- standard projection to see wrist, however may not see fracture clearly, ensure to lower kVp for children
Lateral - best to see fracture line
Radiographic appearance of Greenstick/Torus Fracture
Greenstick: visible break in cortex
Torus: buckling or bulging of the cortex
Salter Harris Fracture
a fracture that occurs through the epiphysis (growth plate)
What projections for Salter Harris Fracture? Explain rationale for each
PA: see if there is any fracture line through epiphysis
Lateral: to assess if there is any anterior or posterior displacement of the fracture
Radiographic appearance of Salter Harris Fracture
visible fracture line through the epiphysis in the wrist
Radiocarpal Dislocation
dinner fork deformity where the proximal row of carpals have dislodged posteriorly
What projections for Radiocarpal Dislocation? Explain rationale for each
PA - standard projection to visualise wrist
Lateral - most important to view the anterior or posterior displacement
Radiographic appearance of radiocarpal dislocation
row of carpals displaced from the radius and ulnar
Scaphoid Fracture
fracture to the small bone that sits at the based of the thumb
What projections for Scaphoid Fracture and avascular necrosis scaphoid fracture? Explain rationale for each
HINT: they are the same projections
PA - standard view to see scaphoid fracture
**PA with ulnar deviation **- see elongated scaphoid clearly, better visualisation of fracture
External Oblique - to display the lateral aspect of the scaphoid and see if any fractures
Lateral - to see if there has been any displacement, any other fractures
Radiographic appearance of scaphoid fracture
fracture through the scaphoid, possible displacement
Avascular necrosis scaphoid fracture
when there is a scaphoid fracture that severs the radial artery in the scaphoid causing the bone to die
Radiographic appearance of avascular necrosis scaphoid fracture
bone may appear more white due to damaged blood supply, fracture in the scaphoid
Post closed reduction
individual is put under anaesthetic and fragment is manually manipulated into place (non-surgical procedure)
