[18F]FDG in childhood lymphoma: clinical utility and impact on management

Abstract

Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) is a very useful technique for the imaging of lymphomas in the adult population. It provides unique information about the behaviour of malignant cells and contributes to more accurate staging of the illness and better assessment of response to therapy. The purpose of this study was to evaluate the usefulness of FDG PET in childhood lymphoma compared with conventional imaging methods (CIMs) and clinical data. Between July 1998 and August 2001, 42 FDG PET examinations were performed using a dedicated PET system (27 examinations) or a hybrid coincidence PET system (15 examinations) for initial tumour staging ( n=7), restaging ( n=5) or assessment of response to therapy or residual masses ( n=30) in 27 children with Hodgkin's disease (HD) ( n=20) or non-Hodgkin's lymphoma (NHL) ( n=7). FDG PET results were compared with CIM findings and clinical data. Since 2000, a standardised questionnaire for evaluation of the clinical impact of FDG PET on both staging and therapy has been sent to the 16 referring physicians and 13 have replied. In all children, FDG PET was performed without any side-effects. FDG PET was found to be very sensitive (Se=12/12) for staging and restaging of the illness, showing more lesions than CIMs, with a 50% patient upstaging rate (6/12). It was very accurate for monitoring response to therapy and for characterisation of residual masses. False-positive results were observed in two NHL patients with thymic uptake and one false-negative result was obtained in a patient whose NHL relapsed 1 month after a negative FDG PET. The questionnaire emphasised the impact of FDG PET on clinical management, which was modified on the basis of the FDG PET results in 23% of patients. As previously demonstrated in the adult population, FDG PET appeared to be a very sensitive imaging technique for staging and restaging of lymphoma in children and was very useful for monitoring the response to therapy.

Potential Pediatric Applications of PET/MR

“…18 F-FDG PET and PET/CT are now recognized as valuable staging procedures for most lymphoma subtypes, with a high sensitivity in patients with classic Hodgkin lymphoma and aggressive non-Hodgkin lymphoma (19). In a retrospective analysis, Montravers et al (17) found that 18 F-FDG PET was sensitive for staging and restaging of disease, showing more lesions than conventional imaging. The authors also reported high accuracies for monitoring the response to therapy and for characterizing residual masses, which occur frequently in approximately two thirds of patients with Hodgkin lymphoma and which mostly represent fibrosis rather than active disease.…”

“…Non-Hodgkin lymphoma and Hodgkin lymphoma account for about 10% and 18% of all childhood cancers, respectively; both have high cure rates (10,17,18).…”

“…The use of 18 F-FDG PET for lymphoma has been assessed extensively in numerous studies (17,19). 18 F-FDG PET and PET/CT are now recognized as valuable staging procedures for most lymphoma subtypes, with a high sensitivity in patients with classic Hodgkin lymphoma and aggressive non-Hodgkin lymphoma (19).…”

Treatment of Hodgkin’s lymphoma in children

“…Diğer görüntüleme yöntemlerinin az volümlü hastalık-larda duyarlılıklarının düşük olması, normal bü-yüklükteki lenf nodunda tümör tutulumunun gös-terilememesi, tedavi sonrası rezidü kitlede fibröz ve nekrotik doku ile aktif tümörün BT veya MRG ile ayırt edilememesi nedeni ile bu sınırlamalara fonksiyonel görüntüleme yöntemi olan 18FDG-PET üstünlük sağlamıştır ve bugün HL'nin tedavi öncesi evrelemesi, tedavisi sırasında ve tedavi bitiminden sonraki cevabın değerlendirmesinde rutin olarak kullanılmaya başlanmıştır. [18,19] Tedaviye yanıtın bilinmesi, prognozu daha iyi olan erken evrelerde daha kısa süreli ve radyoterapisiz tedavi kullanılarak geç yan etkilerin azaltıl-masına; prognozu daha kötü olan ileri evrelerde ise etkin ve daha uzun süreli tedaviler ile sağ kalımın artırılmasına olanak sağlar.…”

Value of18F-FDG PET and PET/CT for Evaluation of Pediatric Malignancies

“…Several investigators reported, for both pediatric HL and pediatric NHL, that additional information obtained on 18 F-FDG PET scans compared with CT scans changed management in up to 32% of patients (20,42,43). The most frequent management impact was avoiding radiotherapy of soft-tissue masses in HL, which did not show significant hypermetabolism on 18 F-FDG PET scans at the end of therapy.…”