Devices and methods for vascular navigation, assessment and/or diagnosis

A location detection system, comprising:

• an elongate body defining a lumen at least partially along a length of the elongate body;
• two or more sensors including at least one proximal sensor and at least one distal sensor each positioned near or at a distal tip of the elongate body;
• one or more openings defined along the elongate body where each of the one or more openings is located between the at least one proximal sensor and the at least one distal sensor and where the one or more openings are configured to emit a fluid having a parameter;
• and
• a controller in communication with the two or more sensors, wherein the controller is configured to track a change in the parameter relating to concentration as determined by signals received from both the at least one proximal sensor and the at least one distal sensor and determine a position of the one or more sensors within a body of a subject based on the change in the parameter relating to concentration as received from both the at least one proximal sensor and the at least one distal sensor.