Imaging

Question 1

What methods are used for diagnosis?

Answer 1

CT / US guided biopsies
Histology required in most cases

Question 2

What imaging is used for staging a cancer?

Answer 2

CT for chest and abdominal malignancies primarily
PET-CT used to detect tumour spread by highlighting areas of intense metabolic activity
MRI used for bone and soft tissue lesions
MRI also used when bone causes artefact in CT imaging eg pelvis, posterior fossa of the brain

Question 3

What imaging is used for response to treatment assessment?

Answer 3

CT and MRI
CXR where appropriate

Question 4

How is response to treatment graded?

Answer 4

CR = COMPLETE RESPONSE, no disease detectable radiologically
PR = PARTIAL RESPONSE, all lesions have shrunk by at least 30%, but disease still present
SD = STABLE DISEASE, <20% increase in size / <30% decrease in size
PD = PROGRESSIVE DISEASE, new lesions / lesions have increased in size by >20%

Question 5

What are general info could you tell a patient about CT scanning?

Answer 5

-Uses X-rays
-Image produced is based on tissue attenuation of X-rays
-Section thickness ranges between 1 and 10mm
-Oral contrast can be given to outline GI tract which can demonstrate intra-luminal pathology / bowel obstruction and prevent misinterpretation of bowel loops as mass lesions
-IV contrast can be given to delineate vascular structures and enhance any tumours, particularly in the liver

Question 6

What concerns should be taken into account for CT scanning?

Answer 6

-Radiation dose (low risk for CT but still can induce malignancies)
-Possibility of pregnancy (WCBA)

Question 7

What info could you tell a patient about MRI scanning?

Answer 7

-Produces high contrast images in any plane
-Gold standard for imaging neurospinal, recital, prostate and MSK tumours
-Also used to stage some head and neck cancers
-Main risk is from extremely strong magnets - risk of death from accidents, risk of damage to pacemakers / ICDs if present, risk of damage to metallic foreign bodies if present (if in eye/brain, must be excluded)

Question 8

What info could you tell a patient about US scanning?

Answer 8

-Image formed from reflection of high-frequency sound waves
-Safe, widely available and inexpensive
-Detects mets in solid organs, duplex/doppler can assess tumour blood flow
-Used in real-time guidance of biopsy and interventional procedures
-Operator dependent so less reliable

Question 9

What info could you tell a patient about nuclear medicine?

Answer 9

-Uses radioisotope pharmaceuticals and their distribution in the body is measured by a gamma-camera
-Given IV or orally
-Principle investigation for detection of skeletal mets

Question 10

What info could you tell a patient about PET scanning?

Answer 10

-Stands for positron emission tomography
-Uses high-energy photons emitted by radioisotopes which can be bound to molecules in the body to form a ‘tracer’
-Can differentiate between benign and malignant lesions
-Usually done with CT to map anatomy and images
-Short half-life of isotopes minimises radiation exposure
-Expensive and minimally available