PET/CT in pediatric oncology

Abstract

Radionuclide functional imaging has become a central part of pediatric oncological practice. There have been a number of major advances in imaging technology in recent years, but multislice CT with PET is the modality generating most interest in cancer imaging. In this review, we discuss the common uses and specific issues with regard to PET-CT imaging in pediatric practice. Brain tumors form a significant percentage of pediatric oncology. Use of FDG-PET in brain tumors has helped distinguish viable, residual, or recurrent tumor from post-therapeutic changes and necrosis. High-grade tumors show high uptake of FDG at diagnosis. FDG-PET results may also not accurately correlate with tumor progression after intensive radiation therapy. FDG-PET has been applied to accurate biopsy of infiltrative tumors, tumor grading, and prognostication. Limited available data also suggest that FDG-PET findings correlate well with histopathology and clinical outcome in children. FDG uptake is generally greater in higher grade lymphomas than in lower grade lymphomas. FDG-PET reveals disease sites that are not detected by conventional staging methods, resulting in upstaging of disease with potential therapeutic review. FDG-PET is useful for assessing need for marrow biopsy, residual or recurrent soft tissue masses seen on CT after therapy. The primary role of FDG-PET in neuroblastoma is in non-MIBG concentrating tumors. [11C]-Hydroxyephedrine ([11C]-HED), an analogue of norepinephrine, and [11C]-epinephrine PET have also been used in evaluating neuroblastoma. Uptake of these tracers is demonstrated within minutes after tracer administration, an advantage over MIBG imaging. The exact roles of FDG-PET in osteosarcoma and Ewing's sarcoma are not definitive. FDG-PET may play an important role in monitoring response to therapy Another diagnostic role may be in assessing patients with suspected metastatic disease.

PET/CT: Técnica, consideraciones e indicaciones en el estudio oncológico de pacientes pediátricos

“…Además, en estos últimos hay expresión aumentada de los transportadores de glucosa y una mayor actividad de la hexoquinasa a nivel mitocondrial 7 .…”

“…Es importante saber que la grasa parda distribuida en cuello, región supraclavicular, axilas, mediastino, paravertebral y perirrenal pueden presentar aumento de la captación principalmente cuando existan condiciones que produzcan su activación (exposición a temperaturas más bajas), que se presenta en forma habitual como una captación bilateral y simétrica del trazador 7 . Es importante disminuirla a través de una adecuada calefacción y mantención de la temperatura del paciente durante el examen.…”

PET-CT in children: where is it appropriate?

“…18 F-FDG-PET/PET-CT has been shown to contribute to all of these aspects in children diagnosed with soft-tissue and bone sarcomas [4, 9]. Further, there is evidence to suggest that tumor activity shown by 18 F-FDG-PET/PET-CT and its change in response to therapy may be predictive of outcomes [10–14].…”

“…PET-CT is proving to be useful in the evaluation of neuroblastoma [4, 5, 8, 15, 16] and Wilms tumor [2, 17–21]. At least in the case of Wilms tumor, preliminary experience suggests that the intensity of metabolic activity seems to correlate with the degree of histological differentiation [18, 19].…”

MRI and 18F-FDG-PET/CT in a rare case of early (precursor) B-lymphoblastic leukaemia with bone involvement as initial manifestation

“…Nowadays PET/CT is gaining increasing importance in the diagnostic work-up of several diseases in pediatric patients [6][7][8], but is not routinely used in ALL yet. The role of PET/CT in pediatric patients needs to be further evaluated, considering the effective dose, ranging from 7.3 to 9.3 mSv, provided by using a standard PET/CT protocol (tube voltage, 120 kVp; tube current, 80 mAs; and abdominal pitch, 1.5:1) [9].…”