title: The role of delayed 18F-FDG PET imaging in the follow-up of patients with alveolar echinococcosis.
abstract: (18)F-FDG PET has already proved its usefulness in the follow-up of patients with alveolar echinococcosis (AE) and has been proposed as a surrogate marker for therapeutic decisions on structured treatment interruption by benzimidazoles. However, standard PET acquisition (1 h after (18)F-FDG injection) lacks sensitivity, and the parasite may stay viable even if (18)F-FDG perilesional uptake has disappeared. The aim of our study was to evaluate the usefulness of delayed (18)F-FDG PET in the management of AE patients.
  
  
  METHODS
  During a 6-y period, 120 PET scans using (18)F-FDG were obtained for 70 AE patients treated by benzimidazoles, without selection. All patients underwent whole-body imaging on a PET/CT device 1 h after (18)F-FDG injection (4 MBq/kg), as well as an acquisition focused on the liver 3 h after the injection. We also analyzed the results of serologic tests.
  
  
  RESULTS
  Of the 57 scans considered negative at the standard acquisition, 13 (22.8%) became clearly positive at the delayed acquisition, and 6 (10.5%) became indeterminate at the delayed acquisition. Furthermore, 20 of 22 scans interpreted as indeterminate at the standard acquisition were considered positive because of clear perilesional (18)F-FDG uptake at the delayed acquisition. Thus, delayed acquisition changed the interpretation in 32.5% of cases. Moreover, of 44 patients treated by benzimidazoles and followed for more than 2 y by regular (18)F-FDG PET scans and specific AE serology, 11 (25%) presented pathologic (18)F-FDG uptake at the delayed acquisition but not at the standard one. In these patients, the treatment was continued despite negative results on standard (18)F-FDG PET and negative serologic findings. On the other hand, in 7 patients with negative delayed (18)F-FDG PET and negative serology, the treatment was safely interrupted with no evidence of disease recurrence during 8-37 mo (mean, 23 mo).
  
  
  CONCLUSIONS
  Our study clearly demonstrated that delayed (18)F-FDG PET greatly facilitated the differentiation between active and inactive liver lesions in AE patients. Also, our results strongly suggested that the combination of delayed (18)F-FDG PET and specific serology would prevent most of the recurrences observed after premature interruption of the treatment based only on standard (18)F-FDG PET.
authors.affiliation: Department of Biophysics and Nuclear Medicine, EA 4662 Nanomedicine Lab, Imagery and Therapeutics, University of Franche-Comté and University Hospital, Besançon, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Caoduro
authors.forename: Clémence
authors.initials: C
authors.lastname: Porot
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Vuitton
authors.forename: Solange
authors.initials: S
authors.lastname: Bresson-Hadni
authors.forename: Frédéric
authors.initials: F
authors.lastname: Grenouillet
authors.forename: Carine
authors.initials: C
authors.lastname: Richou
authors.forename: Hatem
authors.initials: H
authors.lastname: Boulahdour
authors.forename: Oleg
authors.initials: O
authors.lastname: Blagosklonov
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use; D000947:Antigens, Helminth; D001562:Benzimidazoles / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004443:Echinococcosis; D004444:Echinococcosis, Hepatic / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000469:parasitology; D004446:Echinococcus / Q000276:immunology; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012008:Recurrence; D013997:Time Factors; D055815:Young Adult
chemical_list: D000871:Anthelmintics; D000947:Antigens, Helminth; D001562:Benzimidazoles; D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18