Diagnostic Algorithm
Clinical Evaluation
History + Lab
Abdominal ultrasound
First line of image
Magnetic Resonance
If echo is inconclusive
How to Request the MRI
To ensure correct protocol, be specific in your request:
Study:
"MRI of the abdomen and pelvis without intravenous contrast, with a protocol for appendicitis."
Indication/Suspicion:
"Pain in the right iliac fossa with inconclusive ultrasound, rule out acute appendicitis."
Don't forget to include!
- Time of evolution and location of pain.
- Laboratory results (Leukocytes, PCR).
- Findings from the previous ultrasound.
Understanding the Protocol
An appendicitis protocol is a fast protocol and focuses on 3 key sequence types. Click on each one to find out more:
T2 Weighting: The Key to Diagnosis
These sequences are the most important. They make **fluid and edema shine brightly**. They are perfect for seeing inflammation.
What are we looking for?
- Appendix thickened (>7mm) and filled with fluid (white).
- Edema in the periappendiceal fat (diffuse white signal).
- Free fluid in the pelvis.
- See example image
Diffusion (DWI): Confirmation
This sequence detects **restriction of water movement** in inflamed tissues. It is a powerful confirmer of acute inflammation.
What are we looking for?
- Inflamed appendix "restricts" and shines on DWI.
- Helps differentiate pus (abscess) from simple inflammatory fluid.
- See example image
T1 Weighting: The Anatomical Map
It offers an excellent view of the **general anatomy**. It is less useful for viewing inflammation, but helps contextualize the findings.
What are we looking for?
- Delimit the anatomical structures.
- Identify complications such as hemorrhages (which would look shiny).
- See example image