Ultrasonography

Ultrasonography

Standard ultrasonography can be used to investigate the stomach but used conventionally it is less sensitive than other modalities. In contrast, endoluminal ultrasonography and laparoscopic ultrasonography are probably the most sensitive techniques available in preoperative local staging of gastric cancer. In endoluminal ultrasonography , the transducer is usually attached to the distal tip of the instrument. Five layers ( Figure 67.5 ) of the gastric wall may be identified on endolu minal ultrasonography and the depth of invasion of a tumour can be assessed (90% accuracy for the ‘T’ component of the staging). Enlarged lymph nodes can also be identified and the accuracy of the technique is about 80% in this situation. Laparoscopic ultrasonography is also a v ery sensitive imaging modality , to a large measure because of the laparoscopy itself (see Laparoscopy ). Ultrasonography can be used to assess gastric emptying. Swallowed contrast that is designed to be easily seen using an ultrasound transducer is used. Emptying of the contrast is followed directly . The accuracy of the technique is similar to that of radioisotope gastric emptying studies (see Gastric emptying studies ).