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Open Access Research

Target volume definition in high-risk prostate cancer patients using sentinel node SPECT/CT and 18 F-choline PET/CT

Hansjörg Vees1*, Charles Steiner2, Giovanna Dipasquale1, Amine Chouiter3, Thomas Zilli1, Michel Velazquez2, Sophie Namy2, Osman Ratib2, Franz Buchegger2 and Raymond Miralbell1

Author Affiliations

1 Division of Radiation Oncology, University Hospital, Geneva, Switzerland

2 Division of Nuclear Medicine, University Hospital, Geneva, Switzerland

3 Division of Radiology, University Hospital, Geneva, Switzerland

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Radiation Oncology 2012, 7:134  doi:10.1186/1748-717X-7-134

Published: 8 August 2012

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.

Keywords:
Prostate cancer; Radiotherapy; SPECT; Sentinel node; 18 F-choline PET/CT