title: Metabolic response of pelvic and para-aortic lymph nodes during radiotherapy for carcinoma of the uterine cervix: using positron emission tomography/computed tomography.
abstract: OBJECTIVE
  We evaluated the metabolic response of lymph nodes (LNs) using consecutive F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) and correlated the metabolic response with the volumetric response measured by consecutive CT.
  
  
  METHODS
  Twenty-two patients with cervical cancer that had positive LNs underwent preradiotherapy (pre-RT) and inter-RT PET/CT. The metabolic response of the LNs was assessed quantitatively and semiquantitatively by measurement of the maximal standardized uptake value. All patients underwent inter-RT CT simulation after 45 Gy to the whole pelvis and inter-RT PET/CT scans after median 63 Gy to the gross LNs.
  
  
  RESULTS
  A total of 48 pelvic and para-aortic LNs were found on the pre-RT PET/CT. The mean maximal standardized uptake value of nodal disease decreased from the pre-RT of 5.2 (SD, 3.1; range, 1.8-15.6) to the inter-RT of 1.1 (SD, 2.1; range, 0-11.1). Classifying the metabolic response of all 48 nodal lesions on the inter-RT PET/CT, 38 had a complete metabolic response. The initial volume of LNs had no correlation with the metabolic response (r = 0.194, P = 0.186). The metabolic response between the pre-RT PET/CT and inter-RT PET/CT was significantly associated with the volume response between the pre-RT CT and inter-RT CT (r = 0.314, P < 0.05). However, 18 (38%) LNs showed discrepancy between metabolic response and residual LN volume. Six (27%) patients had modified RT during treatment based on inter-RT PET/CT.
  
  
  CONCLUSIONS
  We suggest that the PET/CT can be a useful tool for the evaluation of the interim response of the LNs and aid in selecting patients that need further treatment. The results showed a significant correlation between the metabolic and volumetric responses during RT, although the anatomical changes of LNs would not always represent the metabolic status.
authors.affiliation: Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, South Korea.
authors.forename: Mee Sun
authors.initials: MS
authors.lastname: Yoon
authors.forename: Taek-Keun
authors.initials: TK
authors.lastname: Nam
authors.forename: Woong-Ki
authors.initials: WK
authors.lastname: Chung
authors.forename: Shin Young
authors.initials: SY
authors.lastname: Jeong
authors.forename: Sung-Ja
authors.initials: SJ
authors.lastname: Ahn
authors.forename: Byung-Sik
authors.initials: BS
authors.lastname: Nah
authors.forename: Ju-Young
authors.initials: JY
authors.lastname: Song
authors.forename: Jae-Uk
authors.initials: JU
authors.lastname: Jeong
mesh_terms: D001011:Aorta; D001918:Brachytherapy; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D002584:Cervix Uteri / Q000473:pathology / Q000528:radiation effects; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000528:radiation effects*; D008207:Lymphatic Metastasis; D010388:Pelvis; D049268:Positron-Emission Tomography; D011379:Prognosis; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*
chemical_list: D019788:Fluorodeoxyglucose F18