title: Target volume definition in high-risk prostate cancer patients using sentinel node SPECT/CT and 18 F-choline PET/CT.
abstract: BACKGROUND
  To assess the influence of sentinel lymph nodes (SNs) SPECT/CT and 18 F-choline (18 F-FCH) PET/CT in radiotherapy (RT) treatment planning for prostate cancer patients with a high-risk for lymph node (LN) involvement.
  
  
  METHODS
  Twenty high-risk prostate cancer patients underwent a pelvic SPECT acquisition following a transrectal ultrasound guided injection of 99mTc-Nanocoll into the prostate. In all patients but one an 18 F-FCH PET/CT for RT treatment planning was performed. SPECT studies were coregistered with the respective abdominal CTs. Pelvic SNs localized on SPECT/CT and LN metastases detected by 18 F-FCH PET/CT were compared to standard pelvic clinical target volumes (CTV).
  
  
  RESULTS
  A total of 104 pelvic SNs were identified on SPECT/CT (mean 5.2 SNs/patient; range 1-10). Twenty-seven SNs were located outside the standard pelvic CTV, 17 in the proximal common iliac and retroperitoneal regions above S1, 9 in the pararectal fat and 1 in the inguinal region. SPECT/CT succeeded to optimize the definition of the CTV and treatment plans in 6/20 patients due to the presence of pararectal SNs located outside the standard treatment volume. 18 F-FCH PET/CT identified abnormal tracer uptake in the iliac LN region in 2/19 patients. These abnormal LNs were negative on SPECT/CT suggesting a potential blockade of lymphatic drainage by metastatic LNs with a high tumour burden.
  
  
  CONCLUSIONS
  Multimodality imaging which combines SPECT/CT prostate lymphoscintigraphy and 18 F-FCH PET/CT identified SNs outside standard pelvic CTVs or highly suspicious pelvic LNs in 40% of high-risk prostate cancer patients, highlighting the potential impact of this approach in RT treatment planning.
authors.affiliation: Division of Radiation Oncology, University Hospital, Geneva, Switzerland. hansjorg.vees@hcuge.ch
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Vees
authors.forename: Charles
authors.initials: C
authors.lastname: Steiner
authors.forename: Giovanna
authors.initials: G
authors.lastname: Dipasquale
authors.forename: Amine
authors.initials: A
authors.lastname: Chouiter
authors.forename: Thomas
authors.initials: T
authors.lastname: Zilli
authors.forename: Michel
authors.initials: M
authors.lastname: Velazquez
authors.forename: Sophie
authors.initials: S
authors.lastname: Namy
authors.forename: Osman
authors.initials: O
authors.lastname: Ratib
authors.forename: Franz
authors.initials: F
authors.lastname: Buchegger
authors.forename: Raymond
authors.initials: R
authors.lastname: Miralbell
mesh_terms: D000368:Aged; D002794:Choline / Q000494:pharmacology*; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis / Q000175:diagnosis / Q000473:pathology; D061305:Lymphoscintigraphy / Q000379:methods; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000532:radiotherapy; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18; D017430:Prostate-Specific Antigen; D002794:Choline