IXSI: Interventional X-ray and Scintigraphy Imaging of 99mTc-MAA during the radioembolisation pretreatment procedure

Radioembolisation is a clinically accepted oncological treatment for
unresectable liver tumours. It involves x-ray and nuclear imaging guided
injection of radioactive microspheres into the hepatic artery through a
catheter. Current clinical protocol, as advised by the vendors of the
microspheres, involves a pretreatment safety procedure using 99mTc-MAA
particles, that are injected at the intended therapy location during an extra
procedure prior to the therapy procedure. After this pretreatment procedure,
but before the start of the therapy, diagnostic nuclear scintigraphy and a
SPECT/CT are acquired to rule out excessive lung shunting, shunting to other
organs and to assess microsphere distribution in the liver for dosimetry based
therapy planning. For this nuclear imaging the patient is transferred to the
nuclear medicine department. Limitations of the current workflow include length
of the total treatment, and the inaccuracies introduced by replacing the
catheter during treatment in the exact same location as during the pretreatment
procedure. Introduction of a novel mobile hybrid C-arm (IXSI), capable of real
time x-ray and nuclear imaging and of SPECT/CBCT imaging during the
intervention, may shorten the treatment to a single radioembolisation
procedure, and ensure the same catheter location during pretreatment and
treatment injections. In addition, the availability of hybrid imaging during
the intervention may help to optimise treatment by direct dosimetric feedback

Primary objective: To establish the safety of acquiring 2D and 3D hybrid images
using IXSI in an interventional setting.
Secondary objectives: To evaluate dosimetry of SPECT/CBCT acquired by IXSI.
To image the (hemo-)dynamic processes influencing the distribution of 99mTc-MAA
using hybrid 2D images acquired by IXSI.

First in man, safety study

Angiographic work-up will be identical to the standard procedure up to the
point of 99mTc-MAA injection. Then, 2D imaging of the controlled injection of
99mTc-MAA using IXSI is performed, followed by the acquisition of a SPECT/CBCT
of the liver and lungs by IXSI.

The patients that participate in this study will spend more time in the
intervention room for the pre-treatment procedure. It is anticipated that the
imaging performed by IXSI will take an additional 30 to 60 minutes on top of
the regular procedure time (regular procedure time ranges from 1.5 to 3.5
hours). During imaging with IXSI the patient will receive additional dose from
the fluoroscopy and from the low dose CBCT acquired for the SPECT/CBCT. The
additional dose area product (DAP) will be in the range of 0.23 to 7.1 mGy ·m2,
depending on the kV and mA settings used during procedure. For reference,
current 99mTc-MAA procedure delivers a mean DAP of 31 mGy·m2, ranging from 5.6
mGy·m2 to 77 mGy·m2 (based on 99mTc-MAA procedure of 20 patients). Furthermore,
these patients are all scheduled for a treatment using radiation. The treatment
dose is at least three orders of magnitude higher than the additional dose
delivered by IXSI.
This study will have a limited impact on the standard radioembolisation
treatment since catheter placement is still performed using the Allura
(standard clinical c-arm used for guidance of radioembolisation procedures) and
patients will still receive their clinical SPECT/CT at the nuclear medicine
department. All medical decisions are based on the standard forms of imaging
and the treating physician is blinded to the images produced by IXSI.