Radiology

Question 1

MRI T1 image characteristics + uses

Answer 1

1 tissue type is bright (fat) Anatomical MRI is T1 weighted Best for looking a brain structure

Question 2

MRI T2 images characteristics + uses

Answer 2

2 tissue types are bright (fat + water) Functional MRI is T2 weighted Ideal for tissue oedema

Question 3

What tumours is MRI good for visualising, and what region of the brain is it good for visualising?

Answer 3

Soft tissue tumours

Good if PC is dizziness/ ataxia/ CN involvement - can see posterior fossa on MRI

Question 4

How does a PET scan work?

Answer 4

Detects pairs of gamma rays emitted by postitron-emitting radionuclide = introduced into body on biologically active molecule

Question 5

Use of FDG on PET scans - what is it, how does it work, what is it used to visualise + which cancers are show up well?

Answer 5

Fludeoxyglucose = conc of tracer imaged will indicate metabolic activity as it corresponds to regional glucose uptake Used to explore possibility of metastasis

Good for lymphomas + lung cancer

Question 6

Other tracers used in PET scans

Answer 6

Acetate can be used for prostate cancer

Question 7

How is a PET scan visualised?

Answer 7

Superimposed on CTs, which give anatomical landmarks

Question 8

What is a DEXA scan used for + how are the results shown?

Answer 8

Gives you bone density - shown as a number or on a graph

Question 9

How is a bone scan done + how does it work?

Answer 9

Technetium injected Excreted by kidneys Osteoblasts take up tracer

Question 10

What does a bone scan show?

Answer 10

Tracer goes to site of increase bone remodelling (sclerotic bone mets, healing fractures, osteomyelitis)

Question 11

What are the consequences of bone mets + how are they diagnosed?

Answer 11

Marrow involvement = increased fracture risk, anaemia + spinal cord compression

Bone scan

Question 12

Management of bone mets + SE?

Answer 12

Bisphosphonates = increase density but cause hairline fractures

NSAIDs + RT

Question 13

What are the types of bone mets + what cancers cause each type?

Answer 13

Lytic (kidney, lung cancer) Sclerotic (prostate)

Question 14

Kidney bone mets - what do they look like?

Answer 14

Mainly lytic but can be a mix Very vascular - needs to be embolised before operated on

Question 15

What is CTPA + what is it used for?

Answer 15

CT pulmonary angiogram Used to look for blood clots

Question 16

What imaging is used for staging cancers?

Answer 16

CT used for chest + abdo cancer

Supplemented with PET-CT to detect areas of intense metabolic activity (especially for lung + oesophageal cancer)

Question 17

What is the RECIST system + what are the responses?

Answer 17

Compares treatments in clinical trials

Complete response = no disease detectable radiologically

Partial response = all lesions shrunk by at least 30%

Stable disease = less than 20% increase or less than 30% decrease

Progressive disease = new lesions, or lesions increased >20%

Question 18

How does a CT scan work?

Answer 18

Rotating X ray tube + opposing detector

Computer reconstruction of axial cross-sectional images, based on X rays

Question 19

What is a CT with contrast and what is it used for, when is it to be used with caution?

Answer 19

Outlines GI tract, used to delineate vascular structures + demonstrate tumour enhancement

Can be nephrotoxic

Question 20

What is the risk of developing malignancy from CT scans?

Answer 20

1 cancer per 1000-2000 scans

Question 21

What is MRI used for in oncology - which cancers?

Answer 21

Neurospinal, rectal, prostate + MSK tumours Staging of head + neck cancer

Question 22

How does US work?

Answer 22

Reflection of high frequency sound waves at soft tissue generates image

Question 23

What 3 ways is US used for in oncology?

Answer 23

Detecting mets in solid visceral abdo organs

Used to assess tumour blood flow

Used to guide biopsy