PET/CT for Staging; Past, Present, and Future

Accurate and reproducible staging is crucial for management of malignant lymphomas. Disease stage influences treatment decisions more significantly than any other clinical information in most lymphoma subtypes, and contributes with important prognostic information on its own or as part of clinical prognostic scores. Information derived from medical imaging is the single most important determinant of disease stage, and the introduction PET/CT for lymphoma has led to substantial changes in the concept as well as practice of lymphoma staging. Over time, the most important change in lymphoma staging has been the abandonment of extensive pathologic staging intended in the original Ann Arbor classification. The 2014 Lugano Classification represents the most recent expert recommendation for staging of lymphoma. This revision recognizes the improved diagnostic accuracy of PET/CT over stand-alone CT and recommended PET/CT for routine staging of all FDG-avid lymphomas. Routine bone marrow biopsies are also discouraged in Hodgkin lymphoma as well as in selected cases of diffuse large B-cell lymphoma. The scope of this review is to give the reader insight into the history of staging, the purpose of lymphoma staging in the context of contemporary treatment strategies, and the advantages of PET/CT staging over conventional staging. We also discuss the controversies of PET/CT replacing conventional bone marrow biopsies in different lymphoma subtypes and summarize recommendations by the recent Lugano classification.