Sonographic comparison of intraarterial CO2 and helium microbubbles for detection of hepatocellular carcinoma: preliminary observations.

PURPOSE: To evaluate the usefulness of helium gas microbubbles in the detection of small hepatocellular carcinoma (HCC) lesions relative to that of CO2 microbubbles. MATERIALS AND METHODS: Ultrasonography (US) enhanced with both CO2 microbubbles and helium microbubbles was performed in 15 patients. CO2 microbubbles were injected into the proper hepatic artery under US observation. Next, helium microbubbles were injected. Duration and degree of enhancement with the two types of microbubbles were compared. Ten minutes after helium injection, the whole liver was examined with US to detect additional tumors. When new lesions were detected, biopsy was performed. RESULTS: Duration of enhancement with the helium microbubbles (mean, 37.2 minutes) was significantly longer than that with the CO2 microbubbles (mean, 3.6 minutes; P < .001). The degree of enhancement with helium was greater than that with CO2. Thirteen additional lesions were detected after injection of helium gas. All these lesions proved to be HCC at biopsy. CONCLUSION: The duration of enhancement is significantly longer with helium than with CO2 microbubbles. Therefore, helium microbubbles can be used for examination of the whole liver for detection of additional tumors.