Imaging in Lymphoma: The Key Role of Fluorodeoxyglucose‐Positron Emission Tomography

This review focuses on the impact of new imaging guidelines for fluorodeoxyglucose-positron emission tomography (FDG-PET) on clinical practice and the future directions of lymphoma imaging.Fluorodeoxyglucose-positron emission tomography (FDG-PET) has progressively changed lymphoma management over the past decade, and new imaging guidelines integrating FDG-PET for staging and response evaluation in lymphoma have been recently published [1, 2]. The present review focuses on the impact of these guidelines on clinical practice and the future directions of lymphoma imaging. In lymphoma, we are now facing a therapeutic dilemma, which explains why FDG-PET has gained wide acceptance. New treatments have improved the outcomes in the most common types of lymphoma; however, the classic prognostic factors fail to select the small percentage of patients with a high risk of relapse and treatment failure [3, 4]. In contrast, patients are also at risk of serious treatment-related morbidity and mortality; thus, overtreatment should be avoided in those patients who respond well to therapy. For these reasons, we need new prognostic and predictive factors, a precise determination of the initial disease extent, and an accurate and early assessment of the responsiveness to therapy. The objective is now to personalize treatment to improve cure rates in patients with adverse risk factors and to reduce toxicity in other patients without risking undertreatment or disease, respectively. Imaging using FDG-PET can satisfy many of these requirements. A case report of a patient with diffuse large B-cell lymphoma illustrates a typical use and value of FDG-PET in lymphoma management (Fig. 1).Open in a separate windowFigure 1.Case report: 60-year-old woman with a bulky mediastinal tumor. Eastern Cooperative Oncology Group classification, 1; age-adjusted international prognostic index, 2; lactate dehydrogenase greater than normal. Induction: rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone, with a 14-day schedule (six cycles). Positron emission tomography (PET) performed at baseline (PET0, top); after 2 cycles (PET2, middle), and after 4 cycles (PET4, bottom). PET corrected by attenuation, computed tomography (CT), and PET-CT-fused images are displayed for PET0, PET2, and PET4. PET2 showed a partial metabolic response (score 4, residual uptake in the mediastinal mass moderately increased compared with that of the liver). PET4 showed a complete metabolic response (score 2, some foci of residual uptake slightly increased compared with the mediastinal uptake). Consolidation therapy was autologous stem cell transplantation based on PET2 positivity in the context of a trial [34]. The patient was free of progression after 4 years.