The present invention is directed to a method and system for photoacoustic imaging for guiding medical procedures. A transducer is placed near the site of the procedure. The optical fiber, coupled to an electromagnetic source, such as a laser, is attached to a medical device. During the procedure, the device and optical fiber are inserted into the procedure site where the optical fiber illuminates the procedure site, which has a thickness of approximately 2 mm. Photoacoustic images are acquired to visualize the procedure site as the procedure is proceeding in order to provide real-time guidance. This system is applicable to multiple surgical and interventional procedures, such as transsphenoidal surgery.