The key to evaluating the stomach is to have maximum gastric distension with oral contrast agents. The two most common oral contrast agents are; 
a.    Positive oral contrast agent usually an iodinated base agent like iohexol. We prefer positive contrast in all cases when IV contrast is not used as well as in cases where a fistulous track or perforation is suspected
b.    Neutral oral contrast agent is ideal for detection of smaller tumors as well as infiltration of the stomach by tumor (linitis plastica). Water which is the neutral agent we use is ideal for detection of gastric ulcers as well as GI bleeding. Water is also ideal when 3D mapping especially when cinematic rendering is used.

The evaluation of the stomach also requires IV contrast and we inject 100-110 cc of iodixanol at 4-5 cc second. In routine abdominal CT a single venous phase is typically used but with a high suspicion of gastric tumor or GI bleed the study is done with dual phase acquisition. (arterial and venous)

1. If the stomach is not distended then it is impossible to determine whether the stomach is in fact normal
2. Because of COVID and masking and limiting patient contact all of us have gotten into bad habits and in many cases oral contrast especially in the ER is not used. We need to go back to basics and use oral contrast routinely
3. Water is an ideal contrast agent as it is well tolerated.
4. 750-1000 cc of oral contrast agents (positive or neutral agents) is ideal with the first cup given 20-30 minutes pre-study and the last cup given when the patient sits on the scanner table. The last cup guarantees good distension.
5. The most common errors in the evaluation of the stomach are lack of distension and false positive and false negative studies results.
6. In cases where dual phase acquisition id one we usually scan both phases from diagrams to symphysis. In other cases the arterial phase is only to the crest.
7. For suspected GI bleed look for any high density material in the stomach and the change in appearance from arterial to venous phase imaging. If it remains the same it is likely ingested matter including medication (Maalox)