Antral area

Recent studies have shown that fasting and postprandial antral areas increase in patients with functional dyspepsia and diabetes mellitus compared with normal subjects (Undeland et al. 1997 Hveem et al. 1996). The antral area, and hence antral distention, is a significant determinant of postprandial fullness (Hausken et al. 1992). 

The width of the antral area is measured in a vertical section in which the antrum, the superior mesenteric vein and the aorta are visualized simultaneously. The outer profile of the muscularis propria is outlined and the area calculated automatically (Fig. 22.1). The values obtained of all measurements are given as the average of two successive measurements. 

Fig. 22.1. Standardized section of the antrum. Antral area is outlined...

In order to do so, the subjects are usually seated with their back against the gamma camera and the ultrasound transducer is positioned in the region of the umbilicus. The first measurement is performed within 1 min of meal ingestion, followed by subsequent images at intervals depending on which meal is used. Ultrasound T50 is defined as the time when the antral area is decreased to half its maximum (Horowitz et al. 1993). 

Metastases to the gastric wall originate from primary cancers in the lung, breast, pancreas, testes, and ovaries, but also from malignant melanoma. The last named is classically demonstrated as brown or black submucosal nodules, often with a central necrotic ulceration (Fig. 3.43). Metastases from breast carcinoma may infiltrate diffusely, most typically in the antral area. 

Amplitude of antral contractions is measured as a fraction of relaxed area and the motility index is calculated as the amplitude multiplied by frequency. 

Primary tuberculosis of stomach and duodenum is very rare and usually develops secondary to pulmonary tuberculosis. Simultaneous involvement of the duodenum occurs in 10% of patients. There is increased incidence in patients with AIDS. The radiological appearances are classified as predominantly ulcerative or hypertrophic type (Tishler 1979 Agrawal et al. 1999). The ulcerative form is more frequent and consists of multiple large and deep ulcerations, sometimes with antral fistulas (Fig. 5.10). In the hypertrophic form, there is thickening of stomach and duodenal folds which can lead to pyloric stenosis and gastric outlet obstruction. A narrowed antrum can mimic a linitis plastica appearance. There is usually extensive lymph node involvement in the adjacent areas (Tishler 1979 Agrawal et al. 1999). Sarcoidosis and syphilis have identical appearances on conventional barium studies, both ulcerative and hypertrophic (Fig. 5.11). 

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