Clinical evaluation of a prototype drop-in probe for (robot-assisted) laparoscopic sentinel node biopsy

The sentinel node biopsy procedure is conventionally performed via a
radioguided surgery approach: Upon the injection of a radiolabeled colloid
preoperative imaging is performed to determine the number and location of the
sentinel nodes. Intraoperatively then a laparoscopic gamma probe is used to
guide the surgeon to the radioactive nodes. Prostate cancer sentinel node
biopsy is generally performed via a (robot-assisted) laparoscopic approach for
which then a laparoscopic gamma probe is used. However, because this probe has
to be inserted through a trocar, its maneuverability is limited. Increasing the
maneuverability of the gamma probe has the potential to further optimize the
intraoperative sentinel node biopsy procedure. To this end, together with the
company Eurorad we developed a prototype opto-nuclear probe that can be
inserted through a trocar into the abdomen. Here it can be grabbed by a
(robot-assisted) laparoscopic tool which possibly improves the maneuverability
of the probe.

Primary objectives:
- Determination of the sensitivity of the prototype drop-in probe for
(robot-assisted) laparoscopic sentinel node(s) identification. Obtained results
will be compared to those obtained using the conventional method(s);
- Determination of the work-ability of the drop-in probe during
(robot-assisted) laparoscopic sentinel node biopsy.

Secondary objectives:
- Evaluation of the ease of gripping prototype drop-in probe;
- Evaluation of the maneuverability of the prototype drop-in probe;
- Identification of (tumor-positive) sentinel node(s);

25 Patients will be prospectively included in this study. The number and
location of the sentinel node(s) will be determined following the hybrid tracer
injection and preoperative imaging (current routine). Intraoperatively, a
drop-in probe will be used for sentinel node identification. Findings of this
prototype will be compared to that of the conventional standards (laparoscopic
gamma probe and fluorescence camera).
- In the first 5 patients the drop-in probe will only be evaluated ex vivo *
here sentinel node samples will be evaluated that were using the conventional
approach.
- In the following 20 patients, the drop-in probe will be evaluated
intraoperatively.

On the morning of surgery, ICG-99mTc-nanocolloid will be injected
intraprostatically. Lymphoscintigrams and SPECT/CT imaging will be performed to
determine the number and location of the sentinel node(s).
Intraoperatively, after anesthetizing the patient, sentinel node biopsy will be
performed. For this drop-in probe will be used. The sentinel node(s) will be
localised using the conventional methods (laparoscopic gamma probe and
fluorescence camera) and the drop-in probe (see note).
For each removed sentinel node, the gamma probe status (amount of radioactivity
in the node) and the fluorescence status (amount of fluorescence in the node)
will be documented. Sentinel nodes will be assessed following the standard
sentinel node protocol at the department of pathology department.

Note:
- In the first 5 patients the drop-in probe will only be evaluated ex vivo *
here sentinel node samples will be evaluated that were excised using the
conventional approach.
- In the following 10 patients the sentinel node(s) will be localised using the
conventional methods, whereafter the drop-in probe will be evaluated
intraoperatively.
- In the last 10 patients the sentinel node(s) will be localised using the
drop-in probe, after which the localisation will be evaluated using the
conventional methods.

It will be evaluated if the findings of the drop-in probe are in line with the
findings of the conventional methods. Of specific interest is the
intraoperative sentinel node identification rate via gamma tracing. Also the
clinical utility of the drop-in probe will be evaluated. Obtained results will
be compared tot that of the gamma camera and the fluorescence camera (routinely
used methods).

Due to the proposed research, patients will be kept under anesthesia for an
extra 10-15 minutes.

Risk-analysis revealed no direct risks for the intraoperative use of the
drop-in gamma probe.