Kurzfassung:
Objective: The objective of this retrospective study was to compare the diagnostic value of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET)/CT versus 18F-FDG PET and CT alone for staging and restaging of pediatric solid tumors.
Methods: Forty-three children and adolescents (19 females and 24 males; mean age, 15.2 y; age range, 6 - 20 y) with osteosarcoma (n = 1), squamous cell carcinoma (n = 1), synovial sarcoma (n = 2), germ cell tumor (n = 2), neuroblastoma (n = 2), desmoid tumor (n= 2), melanoma (n = 3), rhabdomyosarcoma (n = 5), Hodgkin´s lymphoma (n = 7), non-Hodgkin-lymphoma (n = 9) and Ewing sarcoma (n = 9) who had undergone PET/CT imaging for primary staging or follow-up of metastases were included in this study. The presence, location and size of primary tumors and metastases was determined separately for PET/CT, PET and CT by two experienced reviewers. The diagnosis of the primary tumor was confirmed by histopathology. The presence or absence of metastases was confirmed by histopathology (n = 62) or clinical and imaging follow-up (n = 238).
Results: The sensitivities for the detection of solid primary tumors using integrated PET/CT (95%), PET alone (73%) and CT alone (93%) were not significantly different (p > 0.05). Seventeen patients showed a total of 153 distant metastases. Integrated PET/CT had a significantly higher sensitivity for the detection of these metastases (91%) than PET alone (37%) (p < 0.05), but not CT alone (83%) (p > 0.05). When lesions with a diameter of less than 0.5cm were excluded, PET/CT (89%) showed a significantly higher specificity compared to PET (45%) (p < 0.05) and CT (55%) (p < 0.05). In a sub-analysis of pulmonary metastases, the values for sensitivity and specificity were 90%, 14%, 82% and 63%, 78%, 65%, respectively for integrated PET/CT, stand-alone PET and stand-alone CT. For the detection of regional lymph node metastases, PET/CT, PET alone and CT alone were diagnostically correct in 83%, 61% and 42%. A sub-analysis focusing on the ability of PET/CT, PET and CT to detect osseous metastases showed no statistically significant difference between the three imaging modalities (p > 0.05).
Conclusion: Our study showed a significantly increased sensitivity of PET /CT over that of PET for the detection of all distant metastases but not over that of CT alone. However, the specificity of PET/CT for the characterization of lesions with a diameter > 0.5 cm was significantly increased over that of CT alone. Further prospective studies in larger and more homogenous groups of pediatric oncology patients will be required to evaluate whether the increased sensitivity and specificity of PET/CT influences patient management and increases long term survival of the patients.