Digestive disorders

IV./3.3.: Computed tomography (CT) and ultrasound (US)

CT examination has no role in the primary detection of gastric ulcer. This imaging method is applied in case of possible complications (perforation, penetration) and malignant transformation. In case of a suspected perforation we must be ascertained if free abdominal air is present. Namely, traditional radiograph performed in supine or lateral decubitus position is often not sensitive enough to detect small amount of free air. The same fact refers to small amount of extragastric fluid collections as well which exit the gastrointestinal tract through perforation. Ultrasound has a similar sensitivity in demonstration of these cases. However, ultrasound is not effective in obese patients, in case of meteoristic bowels and deeply located dorsal wall gastric perforation.

CT provides the utmost, most relevant information on the detection of penetration (US has a limited role in the above mentioned cases). Multidetector computed tomography (MDCT) provides a multiplanar imaging possibility in the contrast/water filled stomach to image ulcer bay, wall thickening etc., and penetration cavity developed in the adjacent organs or in an encapsuled way. Furthermore, imaging of connecting canal is also possible.

Virtual endoscopy is also achievable by CT in the stomach, such as in other luminal organs. Virtual endoscopy has an advantage of imaging the surrounding environment in contrast to optical endoscopy. It is also suitable for the detection of early gastric cancer. This method is recommended for patients who are not suitable for gastroscopy due to other reason. Its disadvantage is that biopsy cannot be carried out during the virtual endoscopy. Ulcus nest filled with tissue debris (detritus) or scrapings can be disturbing but intravenous contrast administration might help to demonstrate the absence of connection with the circulation. Also CT examination is recommended in case of malignant transformation and sui generis developed – not only ulcerative but also polypoid type – gastric cancer in order to investigate the thickness of gastric wall and its environment (infiltration of adipose tissue, regional lymph node status).

Knowledge of clinical anatomy of lymph node compartments is essential:

• - perigastric lymph node compartment,

• - coeliac lymph node compartment,

• - periportal, retroduodenal, retropancreatic, mesenterial lymph node compartment.

CT can be useful in demonstration of gastric ulcer bleeding (and of other gastrointestinal bleeding’ source), if the extravasation site of intravenous contrast material can be detected without using prior luminal filling.