Ablation zone delineation with MRI during thermal ablation of liver tumours

Thermal ablation by radiofrequency (RFA) or microwave ablation (MWA) is a
common technique used for local treatment of liver tumours. Successful ablation
is dependent of achieving a sufficient temperature rise to induce cell death
throughout the tumor, while minimizing heat-induced damage to surrounding
tissues. During treatment however, a non-invasive means of temperature feedback
is currently unavailable, and therefore intraoperative assessment of treatment
efficacy and risk of damage to surrounding tissue is lacking. MRI-guidance of
the thermal ablation procedure could enable non-invasive temperature feedback,
potentially allowing real-time monitoring of the ablation process and
delineation of the true ablation zone during treatment.

To assess the feasibility of real-time MRI temperature monitoring and ablation
zone assessment during thermal ablation of liver tumours.

Prospective, non-randomized, single centre pilot study.

All patients will receive MRI-guided RFA/MWA treatment of liver tumours with
per-procedural ablation zone imaging.

Patients will undergo MR imaging while under general anaesthesia for the
ablation procedure. The per-procedural MR imaging is therefore expected to
place no direct increased burden on the patients. The needle placement is
performed under direct MRI-guidance in a similar methodology as is the current
standard in a routine CT-guided procedure. The total time frame of the
procedure is expected to be similar to that of a routine CT-guided procedure.
However, an additional total anesthesia time of approximately 30 min may be
estimated, especially for the first procedures. This is expected to decrease as
more experience is gained. Most important risk of the study would be unwanted
attraction of metallic objects to the magnet. Such an event would pose hazard
to the patient and/or clinical staff members present in the MRI room. To ensure
proper management of these risks, an MRI safety checklist will be used. In
addition, one staff member will be charged with safeguarding the safe working
environment within the MRI room and is required to be present during all
procedures. With these safety measures, the additional risk to the patient or
operating team is expected to be minimal. Most important potential benefits of
intraoperative MR imaging during the ablation therapy are the possibility to
assess the percentage of the total tumor volume that is ablated, allowing
better insight into the accuracy of the current RFA/MWA treatment. In the
future, the feasibility of having MRI-guidance during the ablation could help
to avoid per-procedural complications by monitoring of temperatures near
adjacent structures-at-risk and allow the ability to visualize the zone of
effective treatment, which may hold predictive value for therapy response and
patient prognosis.