The hot appendix

37 yo M presents with right lower quadrant pain. Pain started about 24 hours prior, and migrated from the umbilicus to the RLQ. Afebrile, with a normal whote count.

Given classic history, a CT scan was obtained, which showed a dilated appendix with adjacent fat stranding, consistent with appendicitis. 

A very useful finding in diagnosing early acute appendicitis is appendiceal hyper-enhancement. This is a feature that has poor inter-observer agreement, and I find it hard to teach my residents how to appreciate. 

On spectral analysis, the appendix shows markedly increased iodine uptake. This is very easy to appreciate, regardless of training level or experience. 

The "hot" appendix shows how spectral CT can help us train our residents to appreciate hyper-enhancement, something that those of us with experience find easy. Quantification of appendix iodine uptake may have a role in diagnosing early acute appendicitis.

Conventional CT with inflamed appendix

Iodine map shows intense uptake in the appendix

Iodine overlay shows "hot" appendix