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What are the conventional diagnostic modalities?
Barium studies
Endoscopy and biopsy
What is barium studies?
- Barium sulphate is a radio-opaque contrast used for outlining the gastro-intestinal tract.
- The high atomic number of barium absorbs more x-ray photons than surrounding tissues.
- Barium appears white on the radiograph.
What are the different types of barium studies?
- Barium swallow and meal - oesophagus, stomach and duodenum.
- Barium follow-through or small bowel study - small bowel
- Barium enema - large bowel
What is the radiation dose in barium studies?
- Barium meal =1.5 mSv
- Barium enema = 7.0 mSv
When do you use cross-sectional imaging?
- CT, MRI & PET
- Initial diagnosis and staging of disease
- Monitoring response to treatment
- Evaluation of residual mass after treatment
- Recognition of complications of treatment
- When there is concern for disease relapse
What is computed technology?
- X-rays produce a digital image of a slice of tissue, usually in an axial plane using computing to create the image
Name the types of contrast agens used in CT imaging?
Oral - dilute iodine based contrast (gastrografin) can be given to outline the gastrointestinal tract
Intravenous - iodine based contrast (Omnipaque) injected into the veins to demonstrate blood vessels or the vascularity of different tissues.
Which two stages is CT imaging used in cancer?
- Diagnosis i.e lung tumour and pancreatic tumour
- Staging : assess local spread e.g. lymph nodes or assess distant spread e.g. liver, lung, bone or brain metastase
What is Magnetic Resonance Imaging?
Strong magnetic field aligns protons (H+) in the body in one direction
Radiofrequency pulse displaces protons and images created by displaying time taken for protons to “relax” back to the original alignment
Name some features of MRI?
- Excellent bone soft tissue detail
- Vessels can be demonstrated
- Brain, spine and musculoskeletal
- abdomen and pelvis
- cardiac imaging
