Monitoring Neural Tissues Properties by Modulated Imaging (MI) (MI)

While compatible with time-modulation methods, MI alternatively uses spatially-modulated illumination for imaging of tissue constituents.

The Modulated Imaging system consists of

1. a light projection system that illuminates the tissue with spatial sinusoid patterns.
2. a CCD camera which collects the diffusely reflected light in a non-contact geometry. The wavelength of illumination can be selected by bandpass filtering of a broadband source,or by use of a monochromatic source.

Lastly, tissue fluorescence measurements can be performed by placing a combination of source-blocking and bandpass emission filters in front of the camera.

The diffusely reflected amplitude of the modulated wave carries both optical property (absorption, fluorescence, scattering) and depth information. Specifically, the sampling depth of the spatially-modulated wave is a function of the frequency of illumination and the tissue optical properties.

During neurosurgery when nervous tissue is exposed by the attending neurosurgeon, intraoperative pictures will be taken using the modulated imager by the investigators.

The imaging procedure may delay completion of the surgical case by an estimated 10 to 20 minutes. This is minimal prolongation considering most brain tumor resections take several hours.

The images acquired will be processed after the surgical procedure and will not be available to the surgeon during the operative procedure.