Imaging

Question 1

Key points to check before x ryas

Answer 1

Check if pregant, esp if pelvic or abdo
Remove metal incl udnerwired bras
Flurooscopy is a vide of continues radioopaque material

Question 2

When is contrast used in CT

Answer 2

in highly vascularised areas to differentiate boundaries eg angiograms for clots

Question 3

What is the best scan for aortic dissection?

Answer 3

CT angiogram chest and abdomen

Question 4

When is CT abdo/pelvus with contrast used

Answer 4

Appendicitis, diverticulitis, bowel obstruction/perforation

Question 5

What is high resolution chest CT and what is it used in?

Answer 5

More slices = extra detail - pulmonary fibrosis and ILD

Question 6

What need to check before do contrast CT

Answer 6

Check kidney function and prev allergic reactions when considering iodine contrast
Need a large bore cannula

Question 7

can u do a CT in pregnancy

Answer 7

No

Question 8

When is contrast CT used vs non contrast for head

Answer 8

non contrast - bleed, stroke, trauma
Contrast - space occupying lesion eg tumour, infection

Question 9

What is contrast induced nephropathy

Answer 9

Creatinine rises after a dose of contrast
May require oral/IVC fluids undergoing CT contrast OR contraindicated

Question 10

How does T1 appear in MRI

Answer 10

Water is dark - used for anatomy and soft tissues

Question 11

How does T2 appear in MRI

Answer 11

Water is bright - pathology eg inflammation or oedema

Question 12

What contrast is used in MRIs

Answer 12

Gadolinium, also enhances vascular structures

Question 13

MRI contraindications

Answer 13

Pacemakers, aneurysm clips, cardiac stents
Claustrophobia
First trimester of pregnancy
MRI safety questionnaries by them or doctor
Transdermal meds removed (some metal in them causes burns)

Question 14

Common indications for MRI

Answer 14

MRI head - MS, space occupying lesion, stroke, inflammation
MRI spine - Cauda equina syndrome
Cardiac - structural, coronary heart disease
MSK - muscle/tendon damage

Question 15

What scan do you use for gallstones

Answer 15

MRCP - as often radiolucent so not visible on x ray

Question 16

Ultrasound considerations

Answer 16

Limited view if larger body habitus
Full bladder for pelvic scan
Fasting for 6 hours prior to abdo scan

Question 17

Common uses of types of US

Answer 17

bdo/pelvic US - gallstones, prenancy, AAA

Transvaginal - ovarian and uterine masses, pregnancy

Bedside - FAST - after trauma - scan for free flud, guided bedside cannulation

Doppler for DVT

Question 18

What is a doppler

Answer 18

An US to check blood flow and pulses

Question 19

Investigation ofr acute cholecystitis

Answer 19

US of abdomen - impacted gallstones cause acute cholecysitits

Question 20

When is mammograms used over US

Answer 20

Women over 40
No pregnanct or lactating
US often also indicated at the same time

Question 21

Examples of nuclear imaging

Answer 21

PET scan - glucose for highly metabolic cancers
DMSA - kidney, DAT - dopamine + thyroid scanning

Question 22

Sensitivity definition

Answer 22

Ability of a test to correctly identify those with the disease (true positive rate) and expressed as a %

Question 23

Specificity definition

Answer 23

Ability of a test to identify people withoyt the disease eg the true negative rate

Question 24

Positive PV definition

Answer 24

The porbability of the disease being present if the test is positice

Question 25

Negative Preficitve value

Answer 25

Porbability that the disease is absent if the test is negative

Question 26

What are predicitive values influenced by

Answer 26

The prevlence of the disease in the population

Question 27

Likelihood ratio calculation

Answer 27

Sensitivity / (1-specificity)