To investigate the role of double contrast-enhanced ultrasonography (DCUS) in the diagnosis of rectal gastrointestinal stromal tumors (GISTs).

In eleven patients with rectal GISTs before surgery, gastrointestinal ultrasound contrast agent were injected into rectal lumen and tumor’s two dimensional ultrasound features were analyzed. Microbubbles were injected into the vein to investigate the feature of lesion microcirculation perfusion. After the surgery, according to the tumor diameter and mitotic count, rectal GISTs were classified as very low-risk, low-risk, intermediated-risk and high-risk tumors. The very low-risk and low-risk tumors were grouped together as one group while the intermediated-risk and high-risk tumors were grouped together as another group. According to ultrasound performance and pathological type, ultrasonic features of rectal GISTs with different risk levels were estimated.

Among all rectal GISTs cases, 63.6% (7/11) were low-risk. Under DCUS, the tumor diameter was less than 5 cm, with regular round, hypoechogenicity, uniform low enhancement and less internal liquefaction necrosis. For the 36.4% (4/11) high-risk cases, under DCUS, the tumor diameter was ≥5 cm, with irregular round or lobulation, mixed hyperechogenicity and hypoechogenicity, nonuniform high enhancement, large blood vessel and common liquefied necrosis region. The biological behavior of rectal GISTs was relevant to lesion size, liquefaction necrosis and enhancement mode of ultrasound contrast and irrelevant to the bound and shape of lesion. The accuracy of DCUS and contrast-enhanced ultrasonography were 90.9% (10/11) and 72.7% (8/11) respectively.

DCUS is considered as an effective tool in diagnosing rectal GISTs and can get useful information of the biological characteristics. It has great value for the diagnosis and treatment of rectal GISTs