With its ultra-high transmission rate, strong anti-interference ability and long-distance transmission advantages, fiber optic cable is widely used in the Internet, telecommunications, radio and television, data centers and other fields, and is a key infrastructure to promote. With its ultra-high transmission rate, strong anti-interference ability and long-distance transmission advantages, fiber optic cable is widely used in the Internet, telecommunications, radio and television, data centers and other fields, and is a key infrastructure to promote. S troke is a leading cause of death and disability. 1 Despite efforts in prevention, early diagnosis, and improved treatments, stroke kills more than 160 000 people every year in the United States alone. 2 Approximately 795 000 Americans per year—1 every 40 s—experience a new or recurrent. Disclosed herein are medical systems, devices, and methods for identifying a blood vessel as a vein or as an artery. The system includes an optical fiber configured for insertion into a blood vessel coupled with a console having a light source, an optical receiver, processors, and logic stored in. A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable but containing one or more optical fibers that are used to carry light.