Intraoperative Xoran X-Cat Mobile CT Scan: Novel Experience in Endoscopic Endonasal Skull Base Surgery

Abstract

Intraoperative real-time imaging with MRI and CT has been used infrequently in skull base surgery over the last two decades and has been limited mostly to academic medical centers. At many centers, including ours, we routinely obtain an immediate postoperative thin-cut CT with axial, sagittal and coronal reconstructions after endonasal skull base surgery to assess for integrity of reconstruction, the presence and degree of pneumocephalus, and the presence of hematoma. Xoran Technologies has developed the X-CT mobile, low-profile, rapid, 45-second, cone beam CT scanner to provide real-time intraoperative or immediate postoperative imaging data while the patient is maintained under general anesthesia prior to the patient leaving the operating room. An IRB-approved pilot study (Western IRB 20190429) was initiated to validate the clinical quality of the X-CT in 20 patients undergoing endoscopic endonasal surgery (macroadenoma: 11, chordoma: 4, skull base meningioma: 3, arachnoid cyst: 1, skull base metastasis: 1). Data collection included specific 6-point imaging criteria of the X-CT images (presence of intracranial air, presence and measurement of midline shift, presence of intraparenchymal or intracranial blood, presence or absence of hydrocephalus, position of bone grafting or fat grafting, position of stents, catheters, and or wires) read by the surgeon. In 20 cases, the surgeon scored the intraoperative study adequate in the scoring scale and clinical utility in 20 cases. An immediate conventional MDCT scan was obtained. The review of the immediate conventional CT scan by the surgeons did not change the clinical impressions or recommendations arrived at with the intraoperative scan. Upon completion of the study, independent radiologist comparison of both imaging studies, side by side was performed to identify if due to imaging quality or intraoperative analysis, discrepancies were found. The results will be reviewed. Additional data collection includes intraoperative scan setup, scan time compared with the time to obtain a conventional scan (9 vs. 20 minutes) and adverse events related to use of the intraoperative CT (none). The radiation dose to the patient was decreased with the intraoperative scan by 42% (CTDI 28.1 mGy intraoperative cone beam and CTDI 48.4 mGy for conventional MDCT scan). This presentation will outline the process our center undertook to integrate the CT scanner into our surgical workflow (including intraoperative video demonstration), examples of imaging quality cone beam intraoperative versus conventional CT scan and provide an initial assessment of potential benefits and limitations of this novel technology. In conclusion, this intraoperative novel technology provides adequate detail and quality and precludes the need for traditional postoperative CT in endoscopic skull base surgery with potential savings in overall procedural efficiency, eliminating patient transportation risk and time and offers the surgical team intraoperative decision making if such events are identified in the operating room while the patient is under general anesthesia ([Figs 1]–[3]).