The Prevalence of Extramedullary AML Detected by 18-FDG/PET-CT: Results from the Prospective PET-AML Trial

Introduction: Acute myeloid leukemia (AML) may present with either concomitant or isolated extramedullary (EM) AML. Data on the prevalence of EM AML are based on retrospective and clinical analyses which rely on findings from physical examination only or on coincidental findings in standard imaging procedures and range from 2.5 to 9.1% (Bakst et al., Blood 2011;118(14):3785-3793). Previous studies identified EM AML as a prognostic factor in patients with AML. 18Fluorodesoxy-Glucose Positron Emission Tomography – Computed Tomography (18FDG/PET-CT) is able to detect highly metabolic tissue and has proven efficacy in imaging studies for various types of malignant diseases. In a pilot study in patients with histologically proven EM AML, we were able to demonstrate a sensitivity of 90% using 18FDG/PET-CT imaging and found additional EM sites in 60% of the patients (Stölzel et al., Haematologica 2011;96(10):1552-1556). The aim of this prospective, observational study was to determine the prevalence of EM AML in patients with newly diagnosed or relapsed AML using 18FDG/PET-CT (ClinicalTrials.gov Identifier: NCT01278069).