Lecture 14: MSK Imaging 2 - Upper Limb Flashcards
What are the characteristics of plain radiography?
utilises ionising radiation
different results based on patient positioning
several limitations
What is a “series”?
a collection of views of a body area
What is a “series” necessary for?
to adequately visualize the area of interest
What is a “series” based on?
based on scenario and clinical question
What is an AP view? What is a PA view?
AP = anterior -> posterior PA = posterior -> anterior
What does a lateral view of the wrist allow understanding of?
alignment of the lunate, capitate, scaphoid and radius
What are the characteristics of computed tomography?
utilises ionising radiation
excellent spatial detail
excellent bone detail
What are the characteristics of magnetic resonance imaging?
no ionising radiation
excellent spatial and soft tissue detail
What are the signal intensities of a T1 weighted image?
bright: fat
intermediate: muscles
dark: water, tendon, fibrocartilage
What are the signal intensities of a T2 weighted image?
bright: water
intermediate: fat
dark: muscle and fibrocartilage
What is the clinical use of a T1 weighted image?
good anatomical detail
good for meniscal pathology
poor sensitivity for soft tissue injury
What is the clinical use of a T2 weighted image?
good for soft tissue injury (esp. tendons)
What are the signal intensities of proton density?
bright: fat
intermediate: water
dark: calcium, tendon, fibrocartilage
What is the clinical use of proton density?
good anatomical detail (esp. menisci and ligaments)
What can a fall with an arm at the side lead to?
fracture of the medial aspect of the clavicle
this is because the medial aspect of the clavicle is the weakest part of the bone
What is the most common type of dislocation?
anterior dislocation of the glenohumeral joint -> shoulder appears flattened
What is a Hill-Sachs lesion?
involves dislocation of the glenohumeral joint and impaction of the humeral head into the glenoid which leaves a structural deformation in the round humeral head
What is a Bankart lesion?
reciprocal fracture to a Hill-Sachs lesion of the inferior aspect of the glenoid labrum
What is the most common cause of a posterior glenohumeral joint dislocation and how can they be diagnosed?
electrocution / seizures
lightbulb sign
What view is used for an inferior glenohumeral joint dislocation?
Garth’s view and patients present in a fixed abducted position
What is the nature of the blood supply to the scaphoid? What does this mean for the scaphoid if it is fractured?
retrograde blood supply
high risk of non-union and avascular necrosis
In which populations is proximal rupture of the biceps tendon common?
In which population is distal rupture of the biceps tendon common?
older populations
younger population
What makes paediatric elbow imaging difficult?
ossification centres can mimic fractures
arise in a predictable order -> clinicians need to be aware of this
What makes the radiocapitellar line useful?
consistent on all views/elbow positions
Where must the anterior humeral line run?
it should run straight through the middle third of the capitulum
What happens when there is a supracondylar fracture?
posterior displacement
