Diagnosis of meningioma by time-resolved fluorescence spectroscopy

Abstract

Meningiomas are slow growing lesions accounting for 15 to 20% of primary brain tumors. Surgical resection is the mainstay of treatment for meningiomas causing symptoms.^{1, 2, 3} The extent of tumor resection directly correlates with prevention of recurrence. Intraoperative biopsy specimens are routinely removed by the neurosurgeon from the main tumor mass and possibly one to several dural margins. Neuropathologic evaluation for rapid intraoperative preliminary diagnosis is often requested. The standard intraoperative tissue specimen neuropathologic evaluation has been the “frozen section.” This process of freezing the tissue, slicing the frozen specimen with a microtome, and staining/analysis can, at a minimum, take 15 to $25\min$ . Multiple intraoperative “frozen section” specimen requests can lead to lengthy increases in operative time, as well as a taxing increase in workload for the surgical pathologist. Certain intracranial characteristics of meningiomas, moreover, can increase the difficulty of achieving a complete surgical resection. The “en plaque” variety and petroclival location of meningiomas are examples of meningiomas that often present difficulty in excising dura involved with tumor. In addition, some meningiomas can invade the subjacent brain parenchyma, usually the cerebral cortex. Although conventional imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) can guide the surgery, each tumor’s intraoperative appearance dictates the ease with which a surgeon will accomplish complete tumor excision. Adjunctive instrumentation may provide additional benefit in achieving the goal of complete tumor resection. Time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) represents a promising technique for identifying tumor in real time and may become an intraoperative adjunct for neuropathologic analysis and completeness of surgical tumor resections.