1 Radiology Of MSK

Question 1

How do x rays work?

Answer 1

A beam of electrons are projected through an object onto an image detector

Question 2

What are the 4 main densities?

Answer 2

Most dense - brightest
Bone
Soft tissue
Muscle/fat
Air
Least dense - darkest

Question 3

Advantages of x rays

Answer 3

Quick
Readily available
Inexpensive
Can be portable

Question 4

Disadvantages of x rays

Answer 4

Ionising radiation
Poor soft tissue contrast resolution

Question 5

Roles of x ray in MSK imaging

Answer 5

• initial imaging for skeletal trauma (fracture), acute bone/joint injury (joint dislocation)
• initial evaluation of chronic bone or joint pathologies

Question 6

What is chronic arthritis?

Answer 6

Loss of joint space due to wear and tear of cartilage

Question 7

Fracture definition

Answer 7

Complete or incomplete break in the continuity of the bone

Question 8

Name the 7 types of fractures

Answer 8

Linear
Transverse
Oblique non displaced
Oblique displaced
Spiral
Green stick
Comminuted

Question 9

Transverse fracture

Answer 9

Crosses bone at right angle to long axis of bone <—>

Question 10

Linear fracture

Answer 10

Parallel to long axis of bone ^

Question 11

Oblique non displaced

Answer 11

Diagonal
Aligned edge of fracture

Question 12

Oblique displaced

Answer 12

Diagonal
Non aligned edge

Question 13

Greenstick fracture

Answer 13

One side of cortex broken, one side in tact

Question 14

Who are greenstick fractures more common in?

Answer 14

Children

Question 15

Comminuted fracture

Answer 15

More than one break
Multiple small fragments

Question 16

What are the three phases of fracture healing?

Answer 16

Inflammatory phase
Reparative phase
Remodelling phase

Question 17

Describe the inflammatory phase

Answer 17

Hours-days
No radiographic callus
Haematoma formation
Tissue death
Inflammation/cellular proliferation

Question 18

Haematoma definition

Answer 18

Solid swelling of clotted blood

Question 19

Callus defintion

Answer 19

Thickened/hard part of skin/soft tissue

Question 20

Describe the reparative phase

Answer 20

Days-weeks
Callus on x ray
Angiogenesis
Soft (fibrocartilaginous) callus formation
Hard callus formation

Question 21

Angiogenesis defintion

Answer 21

Development of new blood vessels

Question 22

Describe the remodelling phase

Answer 22

Months - years
Fracture line becomes completely obscured

Question 23

What does CT stand for?

Answer 23

Computed tomography

Question 24

How does a CT scan work?

Answer 24

Uses radiation to build cross sectional images/slices which can be made into 3D images

Question 25

How long do CT scans take?

Answer 25

A few minutes

Question 26

What can CTs be used for?

Answer 26

Detailed images of bone structure and soft tissue To guide infections, biopsies and aspiration in real time

Question 27

Spiral fracture

Answer 27

Fracture line spirals round in multiple planes

Question 28

Epiphyseal separation fracture

Answer 28

Fracture line extents through unfused growth plate

Question 29

Who are epiphyseal separation fractures more common in?

Answer 29

Overweight young boys during rapid growth spurts

Question 30

Disadvantages of CT

Answer 30

- Use radiation - more than x ray - Motion artefact if patient moves so patient must remain still - Poor soft tissue detail compare to MRI

Question 31

Interpreting CT scans

Answer 31

Densities measured in Hounsfield units HU < 0 HU dark e.g. air, fat 0 - 40 HU shades of grey e.g. soft tissue > 100 HU white e.g bone

Question 32

What appears white, shades of grey and dark on a CT scans?

Answer 32

White - bone Shades of grey - soft tissue Dark - air, fat

Question 33

What can be used to see different structures clearer in CT?

Answer 33

CT windowing

Question 34

What does MRI stand for?

Answer 34

Magnetic resonance imaging

Question 35

How does an MRI work?

Answer 35

A strong magnet is used to generate a magnetic field which causes the protons in hydrogen atoms (body is mainly water) to line up. Radio frequency signal pulses displace the alignment Protons realign after pulses stop which emits a signal Signal is made into image

Question 36

What are MRIs used for in MSK medicine?

Answer 36

Define normal anatomy Detect pathology

Question 37

How will most MSK pathologies appear on fluid sensitive sequences?

Answer 37

Bright

Question 38

How do fat and fluid look on T1 weighted images?

Answer 38

Fat bright Fluid dark

Question 39

How does fat and fluid appear on T2 weighted images?

Answer 39

Fat and fluid appear bright

Question 40

Advantages for MRI

Answer 40

- excellent soft tissue (tendons, ligament, muscles imaging - detailed anatomy of joints - excellent bone marrow imaging

Question 41

Disadvantages of MRI

Answer 41

Noisy Claustrophobia Takes a long time 40-60 mins patient must stay still Doesn’t work with meal/electronics e.g. pacemakers

Question 42

Questions of ask patient before MRI

Answer 42

Claustrophobia Wearing any metal or pacemakers?

Question 43

Advantages ultrasound

Answer 43

No radiation No contraindications/side effects Excellent superficial soft tissue resolution Excellent for tendons and peripheral nerves Dynamic imaging Fluid collections Superficial foreign bodies

Question 44

Disadvantages of ultrasound

Answer 44

Operator dependent Poor deep tissue resolution Limited bone and intra-articular imaging

Question 45

How does nuclear medicine work?

Answer 45

- radioactive material and carrier molecule injected into body and travels to intended part of body - material decays via gamma radiation which is emitted and detected by gamma plates - image is created

Question 46

What is nuclear medicine used for?

Answer 46

To asses areas of metabolically active bone - bone forming metastatic lesions - healing fractures - areas of osteomyelitis