Intraprocedural assessment of Ablation Margins using COMPuted tomography co-registration in primary LivEr Tumor treatment with percutanEous ablation: IAMCOMPLETE primary

Percutaneous thermal ablation is a first line therapy for hepatocellular
carcinoma (HCC) Barcelona Clinic Liver Cancer stage 0/A. The most frequently
used ablation techniques are radiofrequency ablation (RFA) and microwave
ablation (MWA).
Compared to surgery, thermal ablation is associated with lower morbidity and
mortality, shorter hospital stays and lower costs. Yet, local recurrence rates
are higher after thermal ablation compared to resection, especially in HCC >3cm.
A drawback of thermal ablation is that no histological confirmation of
treatment success can be obtained. Treatment success can therefore only be
confirmed using medical imaging techniques. In general, a thermal ablation is
considered to be successful when post-ablation computed tomography (CT)
confirms an area of coagulation necrosis that encompasses the tumor with a
margin of at least 5mm in all directions. Currently there is no validated
method to accurately determine ablation margins. In general, the interventional
radiologist performing the procedure estimates the ablation margins by
two-dimensional measurements and visual qualitative assessment of pre- and
post-ablation imaging.
Co-registration of pre- and post-ablation contrast enhanced CT allows
three-dimensional assessment of ablation margins. In a retrospective study in
103 patients with 110 HCC lesions, CT-CT co-registration was used to determine
the minimal ablation margin after treatment with RFA. Only in 2.7% of patients,
the coagulation zone encompassed the HCC lesions with a margin of at least 5
mm. Patients with a minimal ablation margin of <3mm had a local tumor
progression (LTP) rate of 26.3%, compared to 0% in patients with a minimal
ablation margin of at least 3mm.
Unfortunately, co-registration of a pre- and post-ablation CT is often not
feasible as the shape of the liver may alter due to differences between the 2
scans in patient position and diaphragmatic excursion.
We aim to investigate the feasibility of a scanning protocol that minimizes
errors in co-registration by: 1) performing the contrast-enhanced CT scan
immediately before and after the ablation (with the patient in an identical
position, under general anesthesia as per usual) and 2) by performing both
scans during apnea (after a period of pre-oxygenation). The optimized scanning
protocol is expected to allow accurate three-dimensional assessment of margins
after thermal ablation.

To investigate the feasibility of co-registration with MIRADA XD of pre- and
post-ablation CT using an optimized scanning protocol. Secondary objectives
will be to investigate the reproducibility of CT-CT co-registration, to
determine the duration of CT-CT co-registration, and to investigate the
correlation between ablation margins and local recurrence.

This trial is a prospective, single center, cohort study investigating the
feasibility of co-registration with MIRADA XD of CT-scans acquired immediately
before and after ablation in patients with BCLC stage 0/A HCC.

Patients will undergo thermal ablation under general anesthesia as per usual. A
CT with intravenous contrast will be performed immediately before and after the
ablation, while the patient is under general anesthesia. A CT after ablation is
standard of practice in the LUMC, but the CT prior to the ablation is a study
procedure. Both scans will be performed with the patient in a similar position
and during temporary apnea.

There are minimal risks caused by the additional contrast enhanced CT scan and
the apnea. An additional CT-scan causes higher radiation dose, which is
associated to a minor chance of later carcinogenic expression. Contrast agent
is associatied to renal dysfunction in exceptional cases. Due to the minimal
kidney function as exclusion criteria, we donot expect this to occur. The
temporary apnea afte preoxygenation while scanning is not associated with any
risks and will be conducted under supervision of the anesthesiologist.

The general risk of this study is estimated very low.