Abstract: A system and device to determine the location of a needle as it penetrates through a tissue and into a desired site, such as the epidural space, are described. The system (1000) contains a light guide (1020), a light source (1040), a light sensor (1050), and a logic unit (1060). When the tip of the needle (1010) traverses the relatively dense Ligamantum Flavum, the reflecting plane of the ligament is positioned at or near zero distance relative to the tip of the device. Once the tip enters a less dense epidural space the distance to the reflecting plane becomes greater than zero thus producing a drop in intensity of the reflected light. That drop in the intensity of the reflected light is measured by the light sensor and interpreted by a logic unit to be consistent with entry into the epidural space, allowing the system to provide a signal indicating entry into the epidural space.

Abstract: An ultrasound probe system for guiding introduction of an instrument into a patient includes a disk having a surface and an open channel passing axially through the disk and at least two ultrasound transducer elements disposed on the surface of the disk in a parallel arrangement. The open channel is configured to receive the instrument therethrough to permit alignment of the instrument with respect to the disk. Each of the ultrasound transducer elements is configured to transmit and receive ultrasonic waves for detecting an anatomical structure. A graphical representation of at least a portion of the anatomical structure can be provided for guiding the introduction or insertion of the instrument into the anatomical structure.