A system and method for providing image guidance for placement of one or more medical devices at a target location. The method uses a distance metric based on connectedness of nodes, which is derived from a co-occurrence measure. Also disclosed are compositions as well as methods of treating a disease, substrate silencing, screening agents for therapeutic efficacy against a disease, and methods of screening for disease biomarkers. An inlet is at the proximal end of each of the plurality of windings and an outlet is at the distal end of the plurality of windings. The groove keeps a predetermined distance from the light emitting surface.