Side-firing probe for performing optical spectroscopy during core needle biopsy

A needle biopsy includes the step of inserting an optical spectroscopy probe in the needle and gathering optical information through a window formed in the side of the needle at its distal end. The optical probe includes an illumination optical fiber which conveys light to the tissues adjacent the side window and a detection optical fiber which collects light from the same tissues and conveys it to an optical spectroscopy instrument. Based on the results of the optical spectroscopy measurement, the optical probe may be withdrawn from the needle and a cutter advanced to acquire a sample of the tissues adjacent the side window.