Tropical Medicine Mission Index of Diseases About Tropical Medicine Tropical Medicine Home Page Tropical Medicine Staff

Next Page

General Principles Regarding the Imaging Diagnosis of Cystic Hydatid Disease

All imaging modalities can demonstrate some stages of hydatid cysts, but usually scanning (ultrasound, computerized tomography, or magnetic resonance) provides the best images. All methods of scanning can provide images in multiple planes and no added contrast is necessary, except in CT imaging. Used alone, or in combination, and with knowledge of the laboratory test results, an almost 100% positive diagnosis of hydatid disease can be made in the majority of cases. Imaging may even provide a strong diagnostic probability when immunodiagnosis is equivocal or even (rarely) inaccurate.

In most suspected cases of hydatid disease, usually presenting with a cyst or a mass, ultrasonography should be the first method used to scan the patient, with a chest radiograph added. Sonography is highly accurate (except in the chest, skeleton and CNS), cost effective, and does not need ionizing radiation. CT and MRI often provide additional valuable information, particularly when sonography is anatomically unsatisfactory.

The approach to imaging hydatids thus depends on the availability of equipment and the site of the lesion. Except for lesions in the brain or spine, conventional radiography and US are often sufficient for diagnosis and management. Pulmonary lesions are usually detected on the chest radiograph but, when it is available, CT is helpful for complete topographic evaluation. Evaluation of Type I and Type II lesions in solid organs requires ultrasound and/or CT or MRI. If there are many cysts, CT is usually preferred by the surgeon. Brain hydatids can be imaged by either CT or MRI, but ease of imaging in all planes and detailed depiction of cerebral anatomy with MRI make this method particularly useful. Plain films are often adequate for imaging bone hydatids, but CT and MRI yield more information as to extent of the lesion and possible soft tissue involvement.

Angiography, Doppler sonography and nuclear medicine are only occasionally useful in the diagnosis of cystic hydatid disease and are utilized only when the other modalities are unavailable.

Back to the Table of Contents

Copyright: Palmer and Reeder