Diagnostic imaging and interventional radiology of amebic liver abscesses. Personal experience

PURPOSE: The diagnostic imaging findings in hepatic amebiasis and the capabilities of percutaneous drainage have already been described but some debate is open on both diagnosis and treatment. We report our experience with ultrasound (US) and Computed Tomography (CT) studies of the hepatic amebic abscess and its management. MATERIAL AND METHODS: During the last 4 years we examined 14 patients with liver abscess: 11 men and 2 women; 13 were Italian and 1 African (25-61 years old, mean 36). All subjects underwent US and contrast-enhanced CT (with a conventional scanner in 12 and a helical unit in 2). The first 4 cases were also submitted to US-guided diagnostic aspiration. Six patients were treated with percutaneous drainage under US guidance using an 8-10 F pig-tail catheter which was removed 4-18 days later (mean 6). RESULTS: The abscesses were always single and uniloculated, in most cases located peripherally in the right lobe. They were large (2-11 cm, mean 7) and had round, oval, or irregular shape in 9, 3, and 2 cases respectively. US generally showed the abscess as an inhomogeneously hypoechoic mass with ill-defined walls. CT demonstrated a homogeneously hypodense collection with a thick peripheral hypodense halo; after contrast agent administration wall attenuation was increased between the edematous halo and the cavity, and an incomplete idosense ring appeared. Biphasic helical acquisitions allowed demonstration of some difference between the two vascular phases and yielded other interesting findings. Drug treatment provided complete abscess resolution in 8 patients, though in 2 it was badly tolerated. In one case no improvement was found and the patient was submitted to percutaneous drainage, which was the treatment of choice in the remaining 5 patients. The treatment was successful in all cases, but 1 patient who discontinued the combined medical therapy developed a heterotopic lesion. CONCLUSION: US and CT findings, though variable and partially different from those previously reported, may be considered sufficient for diagnostic assessment, especially if in the proper clinical and biohumoral setting. Both drug treatment and percutaneous drainage (to be considered for selected cases) are effective in the treatment of this type of abscess.