2 Principles
The protocols used in this application were adapted from Ramathibodi emergency radiology handbook [1].
2.1 Steps
Here are the general tips for selecting appropriate protocols.
Step 1: Select Protocols
Select appropriate study protocols based on clinical question of the referring physician. For complex clinical scenario, the protocols (including phases of scan) may be selected to cover a broad range of possible disease processes, while balancing the radiation exposure risk.
Step 2: Add some phase of scan
For certain condition, specific phase of scan may added for better visualization. For example:
- Suspecting hypervascular tumor:
- For example: NMR-CT-HCC: neuroendocrine, melanoma, RCC, choriocarcinoma, thyroid HCC
- Consider adding late arterial phase (upper)
- Liver/kidney transplant
- To assess transplant-related complications which includes vascular or non-vascular causes
- Consider adding late arterial phase (liver or kidney transplant)
Step 3: Contraindication of Oral or Rectal Contrast
Check contraindication for administered oral or rectal contrast, these includes:
Oral contrast is not recommended in the following cases:
- Severe vomitting or unable to eat
- Severe abdominal bloating
- History of aspiration or swallowing difficulty
- Multiple dilated, fluid-filled bowel loops from abdominal radiograph
Rectal contrast is not recommended in the following cases:
- Inability to control bowel movements or administer enema (e.g., poor consciousness, post-AP resection surgery, colostomy)
- Immunodeficiency (e.g., HIV, immunocompromised hosts, neutropenia, undergoing CMT/RT or within one month after receiving such treatments)
- LGIB
- Severe bloating or severely dilated colon (e.g., Cecum diameter > 8 cm)
- R/O Toxic Megacolon
Step 4: Other consideration
Plain Only: There are a few cases where a plain study is performed in emergency abdominal cases:
- Stone
- Ruptured AAA
- Bowel perforation
- Mesenteric ischemia
- Biliary/pancreatic stone