Distribution of Prostate Sentinel Nodes–A Spect Derived Anatomic Atlas

Article Outline

• Purpose/Objective(s)
• Patients/Methods
• Results
• Conclusions
• Copyright

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Purpose/Objective(s) 

The randomized RTOG 94-13 trial revealed that coverage of the pelvic lymph nodes in high risk prostate cancer confers a bNED advantage in patients with ≥15% lymph risk of node involvement. In order to facilitate an improved definition of the adjuvant target volume a precise knowledge regarding the localization of the relevant lymph nodes is necessary. Therefore we generated a three-dimensional sentinel lymph node atlas based on SPECT imaging.

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Patients/Methods 

In 50 patients with prostate cancer a three-dimensional (3D) visualization of the sentinel lymph nodes was performed using a double-headed gamma camera with an integrated X-ray device (Millennium VG & Hawkeye^®, GE) after transrectal intraprostatic injection of ∼250 MBq99mTc-Nanocoll (1, 5–3 h p.i.) followed by an anatomic-functional image fusion. Numbers and 3D-localizations of the sentinel lymph nodes were analyzed.

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Results 

A total of 282 sentinel lymph nodes in 49 of 50 patients (98%) were detected with 0 to 16 nodes per patient (median 5.5, mean 5.6). The anatomic distribution of the sentinel nodes (Martinez-Monge) was as following: external iliac 33%, internal iliac 18.1%, common iliac 13.1%, sacral 8.5%, perirectal 5.7%, left paraaortic 5.7%, right paraaortic 4.6%, seminal vesical lymphatic plexus 3.9%, deep inguinal 1.8%, superior rectal 1.8%, perivesical 1.1%, internal pudendal 1.1%, retroaortic 0.4%, inferior rectal 0.7%, superficial inguinal 0.4%, periprostatic 0.4%.

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Conclusions 

The distribution of sentinel lymph nodes as detected by SPECT imaging correlates well with the distribution determined by intraoperative gamma probe detection. The lower rates of sentinel nodes in close proximity to the bladder and seminal vesicles are probably caused by the radionuclide accumulation in the bladder. In regard to IMRT radiotherapy techniques the presented anatomic atlas may allow optimized target volume definitions.