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Ambient light artifacts can confound Raman spectroscopy measurements performed in a clinical setting such as during open surgery. However, requiring light sources to be turned off during intraoperative spectral acquisition can be impractical because it can slow down the procedure by requiring surgeons to acquire data under light conditions different from the routine clinical practice. Here a filter system is introduced allowing in vivo Raman spectroscopy measurements to be performed with the light source of a neurosurgical microscope turned on, without interfering with the standard procedure. Ex vivo and in vivo results on calf and human brain, respectively, show that when the new filter system is used there is no significant difference between Raman spectra acquired under pitch dark conditions or with the microscope light source turned on. This is important for the clinical translation of Raman spectroscopy because of the resulting decrease in total imaging time for each measurement and because the surgeon can now acquire spectroscopic data with no disruption of the surgical workflow.

During the diagnosis and treatment process for brain cancer, clinicians often need to achieve a brain biopsy to get histological data. However there are risks associated with this procedure: 1) collected samples are not always representative of the tumor and 2) there is a risk of blood vessel rupture when the sample is taken. This type of bleeding occurs between 0.3 and 59.8% of the cases and the mortality rate can be as high as 3.9% (Dammers et al, Woodworth et al). Here we present a diffuse reflectance spectroscopy imaging system directly integrated on a brain biopsy needle to guide surgeon during needle biopsy procedures. To mitigate the risks associated with the procedure, our imaging system combines 18 optical fibers (9 used as white-light sources and 9 used as detectors) to acquire a total of 81 reflectance spectra per acquisition. A tomographic algorithm (Goyette et al) is used to reconstruct an image in the vicinity of the needle based on the optical contrast due to the optical absorption of hemoglobin (Hb) which is the main absorber in brain. The evaluation and characterization tests were first carried out in vitro using tissue-simulating phantoms reproducing human brain optical properties (absorption and scattering).

Brain needle biopsy (BNB) is performed to collect tissue when precise neuropathological diagnosis is required to provide information about tumor type, grade, and growth patterns. The principal risks associated with this procedure are intracranial hemorrhage (due to clipping blood vessels during tissue extraction), incorrect tumor typing/grading due to non-representative or non-diagnostic samples (e.g. necrotic tissue), and missing the lesion. We present an innovative device using sub-diffuse optical tomography to detect blood vessels and Raman spectroscopy to detect molecular differences between tissue types, in order to reduce the risks of misdiagnosis, incorrect tumour grading, and non-diagnostic samples. The needle probe integrates optical fibers directly onto the external cannula of a commercial BNB needle, and can perform measurements for both optical techniques through the same fibers. This integrated optical spectroscopy system uses diffuse reflectance signals to perform a 360-degree reconstruction of the tissue adjacent to the biopsy needle, based on the optical contrast associated with hemoglobin light absorption, thereby localizing blood vessels. Raman spectra measurements are also performed interstitially for tissue characterization. A detailed sensitivity of the system is presented to demonstrate that it can detect absorbers with diameters

Invasive brain cancer cells cannot be visualized during surgery and so they are often not removed. These residual cancer cells give rise to recurrences.