Abstract: In one aspect, the invention relates to a probe. The probe includes a sheath, a flexible, bi-directionally rotatable, optical subsystem positioned within the sheath, the optical subsystem comprising a transmission fiber, the optical subsystem capable of transmitting and collecting light of a predetermined range of wavelengths along a first beam having a predetermined beam size. The probe also includes an ultrasound subsystem, the ultrasound subsystem positioned within the sheath and adapted to propagate energy of a predetermined range of frequencies along a second beam having a second predetermined beam size, wherein a portion of the first and second beams overlap a region during a scan.