Feasibility study to assess the incremental value of DeclipseSPECT during radioactive seed localisation in breast cancer surgery.

Since 2008 we use in this institute, The Antoni van Leeuwenhoek Hospital,
radioactive I-125 seeds for localisation of breast lesions. This technique is a
replacement for the worldwide most used technique, the wire guided
localisation. The wire guided localisation has several disadvantages for both
the patient and the logistics.

Currently, the I-125 markers are localised with a gamma probe. This gamma probe
gives an estimation of the distance from the probe to the I-125 by an acoustic
noise. This signal is a 1D signal and requires expertise from the surgeon.

Since 2012, the NKI-AVL is in the possession of a (non invasive) freehandSPECT
system (declipseSPECT) made possible by an European grand (Estar12115
Realtime). With this system we performed a study to examine the precision of
this system for I-125 localisations (Pouw et al. 2014). This device is now used
in standard clinical practice for I-125 markers at the nuclear medicine
department.
The system is commercialised as an device to localise radioactive sources and
has the relevant certification for this purpose. The device generates a 3D
image of the I-125 seed in the tissue and simplifies the localisation by this
manner. The declipseSPECT is also applied to localise other radioactive
sources. During the procedure the location and the depth of the I-125 seed can
be determined, which possibly enhances the accuracy and speed of the surgical
procedure. An other advantage will be that the gamma probe of the declipseSPECT
system acquires a 3D acquisition of the radioactivitydistribution and has
thereby less problems of interference of compton scatter caused by Tc-99m.

A second step is immediately possible, with the same system an ex vivo scan of
the specimen can be obtained to examine if the I125 seed is localised nicely in
the centre of the tumour lump.

The hypothesis of this study is that the surgeon may be assisted by
freehand-SPECT localisations of the I125 seed and thereby more accurate tumour
excision will be accomplished. This may lead to improved quality of care for
this specific patient group.

Primary Objective: The primary objective of the present study is to assess the
feasibility of using the declipseSPECT system for accurate I-125 seed
localisations in breast cancer surgery.

Secondary Objective(s):
• Assess the accuracy of I-125 seed detection with freehand-SPECT compared to
conventional gamma probe localisation.
• To determine if it is feasible to predict the accuracy of a tumour excision
based on the location of the I-125 in the excision specimen.

Twenty patients scheduled for lumpectomy for breast cancer tumour excision
undergo an additional 5-10 minutes I-125 seed localisation by freehandSPECT
during surgery after localisation with the conventional gamma probe.

The location of the I-125 seed is marked on the skin after localisation with a
gamma probe, directly after this localization a (non-invasive)
freehand-SPECT-scan is performed and the concordance between the two
measurements is written down. The difference is photographed.

The rest of the procedure is according to standard protocol where the excision
takes place by guidance of the standard gamma probe. After excision another
scan is made of the specimen at the operating room to assess the location of
the I-125 seed within the specimen. The closest margin is written down.

For the surgeon and patient the whole surgical procedure is according to
standard clinical protocol except for the additional freehand-SPECT scan. The
surgeon evaluates after excision if the localisation with the two techniques
was similar.

Participation does not impose any significant risks for patients or staff. The
only thing changing is a delay of maximum 5-10 minutes in surgery time. This
causes an extended time of narcosis with the known involved risks.