The usefulness of EUS elastography in the diagnosis of upper gastrointestinal submucosal tumor

Objective: To explore the EUS elastographic pattern of upper gastrointestinal submucosal tumor (SMT), and the potential usefulness of EUS elatography for the benign and malignant determination. Methods: Between January 2009 and May 2010, a total of 24 patients (14 males, 10 females, mean age 57.1 years) who received EUS examination in our department because of SMT were enrolled. The locations of lesion were 8 cases in esophagus, 13 cases in stomach and 3 cases in duodenum. The sizes of lesion ranged from 0.6 to 7.1cm, with an average of 2.42cm. Real-time elastography was carried out during the conventional EUS examination. Compression was naturally obtained by arterial pulsations and respiratory movements. The relative stiffness of tissue was described by colors superimposed on the B-mode image: hard tissue areas were marked with blue, intermediate areas with green, medium soft areas with yellow and soft areas with red. The final diagnosis was based on the histopathology of specimen resected by surgery or endoscopy. Results: Elastography was successfully performed in all patients. We classified elastographic patterns into four different types based on the color composition of SMT's elastographic image: type I was assigned when the image showed a homogenous green area; type II was a mixture with green, yellow, and red; type III was heterogeneous color mixed with blue, green, yellow and red; type IV was heterogeneous pattern with blue dominated mixed color. The correspondence between histopathology and elastographic pattern is shown in table 1. The results demonstrats that elatographic pattern of benign SMT and low risk GIST tends to be type I, II and III. On the other hand, all moderate/high risk GIST shows an elatographic pattern of type IV. Furthermore, the lesion mainly displays type I and II pattern when smaller than 2cm. When larger than 2cm, type III and IV become the most common pattern. This may be explained by the commonly appearance of liquefaction and necrosis in larger lesion. Unlike pancreatic lesion, there was no homogenous blue pattern appearing in SMT. Conclusions: There are apparent differences in elastographic pattern between benign SMT, low risk GIST and moderate/high risk GIST. EUS Elastography may provide a potential role in the benign and malignant determination of SMT.

Table 1:

	type I (n)	type II (n)	type III (n)	Type IV (n)
Leiomyoma	4	3	0	1
Lipoma	2	1	0	0
Schwannoma	0	0	1	0
Low risk GIST	3	1	2	1
Moderate/high risk GIST	0	0	0	5