A functional dynamic scoring model to elucidate the significance of post-induction interim fluorine-18-fluorodeoxyglucose positron emission tomography findings in patients with Hodgkin's lymphoma

Background The findings of interim fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET/CT) predict progression-free survival of patients with Hodgkin's lymphoma. Historically, the assessment was based on a static all-or-none scoring system. However, the clinical significance of any positivity in interim FDG-PET/CT has not been defined. Design and Methods Ninety-six patients with Hodgkin's lymphoma who underwent interim FDG-PET/CT were evaluated using dynamic and visual scores, employing mediastinal or liver blood pool uptake as a comparator. FDG-PET/CT was prospectively defined as positive if any abnormal F(18)FDG uptake was present. In a retrospective analysis dynamic score 0 indicated resolution of all disease sites; score 1 defined a single residual focus; score 2 denoted a reduction in the number of foci; score 3 defined a reduction in intensity with no reduction in number; and score 4 indicated no change in the number and intensity of foci or appearance of new foci. Results The dynamic visual score review reduced the number of positive interim studies from 24 to 6 if a score of 2 or less was considered negative, with significantly better specificity (96%) as compared to static visual scores (78%-86%). The 5-year progression-free survival and overall survival rates in patients who had a negative dynamic score were 92% and 97%, respectively; the corresponding figures for patients with positive results were 50% and 67%. Conclusions A dynamic visual score may be a better indicator for tailoring therapy than static visual scoring.