title: Role of PET/CT in malignant pediatric lymphoma.
abstract: BACKGROUND
  Malignant pediatric lymphoma accounts for 10-15% of all pediatric cancers, (representing 2-3% of all malignancies), with a peak incidence between 5-9 years. Chemotherapy is usually the first and most common mode of treatment. The choice of treatment and prediction of prognosis depend on the histological type of tumor, initial staging, evaluating treatment response, and detection of early recurrence. Conventional imaging modalities have many limitations. PET/CT is more accurate, however so far the literature lacks the results of a large group of patients.
  
  
  OBJECTIVE
  To report the role of PET/CT in the above-mentioned objectives at the newly established Children's Cancer Hospital in Cairo, Egypt, which is one of the busiest dedicated pediatric oncology centers of such purposes in the world. All findings were proven by histopathology, clinically, and by clinical follow-up.
  
  
  METHODS
  A total of 152 patients (35 girls and 117 boys) with histologically proven malignant lymphoma (117 HD, 35 NHL) were included in this study. They were divided into four groups. Group I: 41 patients for initial staging. Group II: 51 patients for evaluating early treatment response after two to three cycles of chemotherapy. Group III: 42 patients for evaluating treatment response 4-8 weeks after the end of their treatment. Group IV: 18 patients evaluated for long-term follow-up. Results of PET/CT were compared with the other conventional imaging modalities (CIM).
  
  
  RESULTS
  The sensitivity, specificity, accuracy, and positive and negative predictive values of PET/CT and CIM were as follows: In Group I: PET/CT modified staging and treatment in 11 out of 41 cases (26.8%), upstaged 5(12.2%) patients and down-staged six (14.6%) patients. Group II: 100%, 97.7%, 98%, 85.7%, 100%, respectively, for PET/CT and 83%, 66.6%, 68.6%, 25%, 96.7% for CIM respectively Group III: At the end of chemotherapy 100%, 90.9%, 92.8%, 75%, 100%, respectively, for PET/CT and 55.5%, 57.5%, 57.1%, 26.3%, 82.6% for CIM, respectively. Group IV: For long-term follow-up, all the parameters scored 100% for PET/CT, 100%, 38.4%, 72.2%, 50%, 100% for CIM, respectively.
  
  
  CONCLUSIONS
  PET/CT in pediatric lymphoma is more accurate than CIM. We recommend that it should be the first modality for all purposes in initial staging, evaluating treatment response and follow-up.
authors.affiliation: Department of Nuclear Medicine, Children's Cancer Hospital, Cairo University, Cairo, Egypt.
authors.forename: Raef
authors.initials: R
authors.lastname: Riad
authors.forename: Walid
authors.initials: W
authors.lastname: Omar
authors.forename: Magdy
authors.initials: M
authors.lastname: Kotb
authors.forename: Magdy
authors.initials: M
authors.lastname: Hafez
authors.forename: Iman
authors.initials: I
authors.lastname: Sidhom
authors.forename: Manal
authors.initials: M
authors.lastname: Zamzam
authors.forename: Iman
authors.initials: I
authors.lastname: Zaky
authors.forename: Hussein
authors.initials: H
authors.lastname: Abdel-Dayem
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis*; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*