A New Frontier of Intraoperative Imaging for the Resection of Skull Base Tumors: A Systematic Review

Introduction: Skull base surgery for the removal of brain and spinal cord tumors is a significantly vital, yet operationally difficult subset of neurosurgery. The greater quantity of tumor removed, with gross total resection (GTR) often the goal, has been shown to improve lifespan, decrease morbidity and mortality rates, and lessen postoperative complications. Intraoperative imaging techniques including intraoperative magnetic resonance imaging (iMRI), computed tomography (iCT), ultrasound (iUS), and fluoroscopy have become more widely utilized and efficacious for the removal of skull base tumors. A review of the literature can provide neurosurgeons with information regarding the advantages and disadvantages of each technique, the types of tumors that each is best suited for, and if improved resection rates are more attainable with their use.

Methods: A systematic literature review was conducted using PubMed and selected based on strict inclusion and exclusion criteria. Articles were screened independently by two reviewers and a third reviewer was used to settle any conflicts. The gathered information was organized and analyzed using Excel.

Results: Our review resulted in the inclusion of 26 articles. The total cohort consisted of 732 patients with a gender predominance of 1.35:1 female:male and a mean age of 50.9 years old. The most common tumor types studied were pituitary adenoma (n = 63%), meningioma (n = 19%), and chordoma (n = 10%). An endoscopic transsphenoidal approach was used in 46% of patients and microscopic transsphenoidal in 33% of cases. The majority of iMRI cases were used for pituitary adenoma and most iCT cases were for meningioma. Using intraoperative imaging techniques, GTR was achieved in almost half of the tumors operated on with an additional 10% reporting near-total resection (NTR) indicating less than 10% residual tumor. 54% of GTR was attributed to using iMRI and 42% to iCT. iUS and fluorescence studies reported positive impacts on visualizing important vessels and tumor identification.

Conclusion: The results of this systematic review can aid neurosurgeons in making informed decisions about using intraoperative imaging techniques in skull base tumor surgeries. When safe, the total removal of a brain tumor defined as GTR should be a goal of the operation. Before the use of intraoperative imaging, the tumor remnant was subject to the surgeon’s estimate and expertise. Updated navigation techniques provide an objective measurement of the remaining tumor and thus act as a method of quality control. The availability of different techniques such as iMRI, iCT, iUS, and fluorescence provide options depending on the need to identify eloquent soft-tissue structures, bony involvement, or vital vessels.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
07 February 2025