PET imaging in pediatric Hodgkin's lymphoma

Advances in diagnostic imaging technology, especially functional imaging modalities like positron emission tomography (PET), have significantly influenced the staging and treatment approaches used for pediatric Hodgkin's lymphoma. Today, the majority of children and adolescents diagnosed with Hodgkin's lymphoma will be cured following treatment with non-cross-resistant combination chemotherapy alone or in combination with low-dose, involved-field radiation. This success produced a greater appreciation of long-term complications related to radiation, chemotherapy, and surgical staging that prompted significant changes in staging and treatment protocols for children and adolescents with Hodgkin's lymphoma. Contemporary treatment for pediatric Hodgkin's lymphoma uses a risk-adapted approach that reduces the number of combination chemotherapy cycles and radiation treatment fields and doses for patients with localized favorable disease presentation. Advances in diagnostic imaging technology have played a critical role in the development of these risk-adapted treatment regimens. The introduction of computed tomography (CT) provided an accurate and non-invasive modality to define nodal involvement below the diaphragm that motivated the change from surgical to clinical staging. The introduction of functional imaging modalities, like positron emission tomography (PET) scanning, provided the means to correlate tumor activity with anatomic features generated by CT and modify treatment based on tumor response. For centers with access to this modality, PET imaging plays an important role in staging, evaluating tumor response, planning radiation treatment fields, and monitoring after completion of therapy for pediatric Hodgkin's lymphoma. This trend will likely increase in the future as a result of PET's superior sensitivity in correlating sites of tumor activity compared to other available functional imaging modalities. Ongoing prospective studies of PET in pediatric patients will increase understanding about the optimal use of this modality in children with cancer and define the characteristics of FDG-avid nonmalignant conditions that may be problematic in the interpretation of tumor activity.