Pericystic metabolic activity in alveolar echinococcosis: Assessment and follow-up by positron emission tomography

Information on parasite viability in alveolar echinococcosis (AE) cannot be obtained by conventional imaging techniques. We evaluated the glucose meta bolism of AE lesions by use of [F-18]fluorodeoxyglucose positron emission t omography (FDG-PET) in 12 inoperable patients. Eight patients showed either perilesional or focal enhancement ("hot spots"), whereas 4 patients had no nenhancing (metabolically inactive) lesions. With PET, necrotic parasitic l esions and areas of enhanced metabolic activity could be clearly discrimina ted. Most notably, 3 of 8 patients with metabolically active lesions who we re reexamined after chemotherapy treatment clearly showed improvement: the initial surrounding hot spots had disappeared in 2 of them, and had signifi cantly decreased in 1. PET may prove valuable in assessing the efficacy of chemotherapy by showing the disappearance of metabolic activity and may als o be useful for timely detection of relapses and metastases. Although costl y and not readily available, FDG-PET is a promising tool toward improved ma nagement of AE and may thus help lower costs of long-term chemotherapy.