System and method of chemical imaging using pulsed laser excitation and time-gated detection to determine tissue margins during surgery

A method comprising:

• irradiating, with substantially monochromatic pulsed laser light, a region containing a biological tissue to thereby produce Raman scattered photons;
• detecting said Raman scattered photons using time-gated detection to thereby obtain a Raman spectroscopic image from the irradiated region for at least one Raman spectroscopic value characteristic of at least one of a neoplastic portion in said region containing the biological tissue and a non-neoplastic portion of said region containing the biological tissue, wherein said Raman spectroscopic image comprises spectral information recorded at each pixel in the image;
• differentiating a boundary between the neoplastic portion and the non-neoplastic portion in the region containing the biological tissue wherein said differentiating comprises analyzing said spectral information recorded at each pixel of said Raman spectroscopic image using a method selected from the group consisting of:
• principle component analysis, cosine correlation analysis, Euclidian distance analysis, multivariate curve resolution, band t. entropy method, mahalanobis distance, adaptive subspace detector, and combinations thereof;
• and
• displaying a location of said boundary in said Raman spectroscopic image.