High-sensitive fluorescence endoscope using electrocardiograph-synchronized multiple exposure.

Abstract

PURPOSE: Fluorescence-based measurement of cardiac disease, using autofluorescent substances that already exist in the heart, has not been used for endoscopic surgery because the endoscopic lenses cannot transmit sufficient light. A highly sensitive fluorescence endoscope using an electrocardiograph (ECG)-synchronized multiple exposure (ESME) approach was developed that provides a bright fluorescent image. METHODS: A system was developed consisting of an endoscope, an excitation light, an ECG amplifier, a trigger and delay unit, and a computer. This system is based on periodic motion of the heart. Since the shape of the heart can be photographed by ECG triggering in a similar manner, a bright image can be synthesized by accumulating multiple trigger-captured images. Laboratory and in vivo experiments were performed to confirm the effectiveness of ESME. RESULTS: The experimental results revealed that the trigger unit generated the synchronization signals required to produce high-quality images of the heart depending on heart rate. The difference among trigger-captured images from the actual organ, which affects the quality of ESME images, was estimated at 0.65 mm from the calculated displacement of a marker on the heart. The results also revealed that a bright fluorescent image can be captured by ESME. CONCLUSION: A highly sensitive fluorescence endoscope using ESME was developed and successfully tested. The experimental results indicated that the method enabled high-quality image acquisition in a very low illumination environment. This system is effective for the observation of faint fluorescence in the heart and is useful for the intraoperative examination of the heart status.