Imaging in cancer Flashcards
What imaging methods can be used to diagnose and stage cancer
Plain radiographs Barium studies CT MRI PET
What is barium sulphate
A radio-opaque contrast used for outlining the gastro-intestinal tract
How does barium sulphate in barium studies work
The high atomic number of barium absorbs more x-ray photons than surrounding tissue
What colour does barium appear on radiographs
White
What does a barium swallow and meal show
Oesophagus
Stomach
Duodenum
What does a barium follow-through (small bowel study) show
Small bowel
What does a barium enema show
Large bowel
How does a patient prepare for a barium meal and follow-through
Fast for 4-6 hours
How does a patient prepare for a barium enema
Low residue diet for 48 hours
Bowel cleansing with picolax
What is a CT scan
When X-Rays produce a digitay image of a slice of tissue, normally in an axial plane, using computing to create the image
What type of cross sectional imaging is used for the initial diagnosis and staging of cancer
CT
MRI
PET
What can CT, MRI and PET also be used to identify
Response to treatment
Evaluation of mass after treatment
Complications of treatment
Concerns for replase
What is a hounsfield unit
Attenuation values of voxels are expressed as a CT number which relates the attenuation value to that of water
Ranges from +3000 (bone) to -1000 (air).
Can CT images be reconstructed
Yes
What type of CT contrast agents are there
Oral
Intravenous
What is an oral CT contrast agent
A dilute iodine based contrast (gastrografin) which can be given to outline the gastrointestinal tract
What is an intravenous CT contrast agent
An iodine based contrast (omnipaque) inject into the veins to show blood vessels or the vascularity of different tissues
How can imaging help in diagnosis and staging
It shows the: Position of the tumour Depth of penetration of the tumour Relationship to adjacent structures Involvement of regional lymph nodes Presence of distant metastases
What types of tumours do CT scans help diagnose
Lung tumours Pancreatic tumour Renal tumours Adrenal tumours Retroperitoneal tumours Brain tumours
How do CT scans help stage cancers
They assess the local spread (e.g. lymph nodes, adjacent organs) and assess the distant spread (e.g. liver, lung, bone or brain metastases)
What type of cancers are imaged using MRI’s
Brain Spinal cord Head and Neck Liver Rectum and anal Kidney Bladder Prostate Ovary Cervix, vagina, vulva Uterus Lymphoma - CNS/MSK Musculoskeletal
How can CT scans monitor cancer
By making 2D measurement
What do CT scans monitor in cancer
Response to treatment
Relapse
Progression of disease
How many mSv is a patient exposed to from a chest CT
8
How many mSv is a patient exposed to from an abdomen CT
10
How many mSv is a patient exposed to from a pelivs CT
10
What is 10 mSv equivalent to
500 return flights from Manchester to Malaga
4 years in Aberdeen
What does the ALARA stand for
As low as reasonably achievable
What is the ALARA principle
It ensures whether the examination is necessary
There must be adequate clinical information for appropriate protocol and repeat examinations should be avoid
What does CT stand for
Computed tomograph
What does MRI stand for
Magnetic resonance imaging
How does an MRI scan work
Human body made up of various elements such as: hydrogen, oxygen, phosphorous etc.
The strong magnetic field aligns the protons (H+) in the body in one direction
A radiofrequency pulse will displace protons
The images are created by displaying the time taken for protons to ‘relax’ back to the original alignment
State the indications for an MRI scan
The excellent bone soft tissue detail If the vessels can be seen Brain, spine and musculoskeletal studies Abdomen and pelvis studies Cardiac imaging
What are the contraindications of an MRI scan
It is claustrophobic and noisy
The motion artefact
It cannot image patients with pacemakers, aneurysm clips etc.
Name a MRI specific contrast agent
Gadolinium DTPA
What is gadolinium DTPA
An intravenous contrast medium that causes changes in the local magnetic field, so alters the tissue signal
Name 3 NHS screening programmes available
Breast
Bowel
Cervical
What are the WHO principles of screening
- Condition should be an important health problem
- There should be a latent stage of the disease
- There should be a test or examination for the conditions
- Test should be acceptable to the population
There should be treatment for the condition - Facilities for diagnosis and treatment should be avaliable
Which NHS screening programmes involve imaging
Breast
Ovarian
Lung cancer
What type of screening is used for breast cancer
Mammography
What type of screening is used for ovarian cancer
TVUS (research)
What type of screening is used for lung cancer
Spiral CT (research)
What are the advantages of screening
Detects disease at an early stage where treatment can alter outcome
Test causes no harm
Test has high sensitivity and specificty
Benefits the individual and the population
What are the disadvantages to screening
Cost
Exposure to radiation
