Intraoperative control of maxillary malignancy resection with cone-beam computed tomography

Maxillary malignant neoplasms constitute a group of tumours that present often
at an advanced stage. Their surgical management can be, thus, challenging,
regarding also their proximity to significant structures like the orbit and the
brain. Particularly, cases with extensive disease and recurrent tumours are
often incompletely resected and local failure is commonly observed, ranging
from 30% to 50%. The use of intraoperative imaging can be an additional tool
for verifying the complete tumour resection.

Primary Objective
1. Investigate the feasibility of intraoperative imaging with CBCT in open
maxillectomy for verifying resection of the intended treatment volume.
2. Assess the feasibility of the intended treatment volume segmentation and
resection planning based on the preoperative imaging.

This is a prospective study which has the character of an exploratory pilot
study, establishing the implementation of CBCT in patients undergoing
maxillectomy for malignant tumours.

Preoperative imaging with MRI of the maxilla will be obtained for all patients.
Segmentation of the resection area will be then performed on the coronal and
transverse sections of the MRI scans of each patient.

The study will be performed in two distinct phases:

* In the first phase, three patients will undergo the conventional open
maxillectomy procedure and the intraoperative imaging with the CBCT. Comparison
of the preoperative and intraoperative scans will be conducted, using imaging
fusion of the MRI and the CBCT scans. No further intervention will be applied
to this group, independently of the result of the intraoperative imaging.

* In the second phase, three patients will also undergo the primary resection
and the intraoperative imaging. However, if the comparison of the preoperative
with the intraoperative imaging reveals residual tumour that is included in the
preoperative imaging resection planning, then the surgical procedure will
continue in order to excise the target tissue. In this case a second CBCT will
be carried out to confirm the complete resection.
Three patients will be recruited for each phase of the study.

Burden:
The burden for the individual patient is the extra operating time it takes due
to additional imaging procedure (approximately 15 minutes for each CBCT scan).

Risks:
Open maxillectomy is a well-established, routine treatment modality and the
general risks are well known. The only extra risk involves the additional
exposure to ionizing radiation, although the dose of a CBCT scan is
significantly lower than that of a conventional CT of the head and neck.

Benefits:
For the patient: The surgeon*s experience is a significant factor for complete
tumor excision and, thus, for a successful maxillectomy. In this study, control
of the resected area will be performed based on the comparison of the
intraoperative CBCT with the preoperative imaging (MRI) planning. This way,
complete tumour resection (according to imaging) will be confirmed. Resection
free margins according to intraoperative imaging can potentially increase the
possibility of pathologically free margins, which in turn is a major predictive
factor of prolonged survival. Moreover, the use of imaging provides an
additional tool for the control of the proximity to significant anatomical
structures, and thus decreasing the complication rates.
Benefits in general: The use of CBCT suggests an innovative imaging technology
that may have an important contribution in the radical excision of maxillary
malignant tumours, affecting positively on the patients* prognosis. Thus, the
current study may have a significant impact on the way the procedure is
nowadays performed.