COMPRESSIVE LAMINAR OPTICAL TOMOGRAPHY FOR ACTION POTENTIALS IN CARDIAC TISSUE
Takumi Harada, Naoki Tomii, Etsuko Kobayashi, Ichiro Sakuma
University of Tokyo, Japan
Fluorescent tomography has been used for identifying tumor position which stays motionlessly. The propagation of electrical activity in the brain or the heart is the fast activity which propagates several tens of meters a second and the 2D activity on the tissue surface has been measured using the membrane potential sensitive dye. However, the conventional tomography system based on the raster scanning is time consuming measuring method and cannot measure the 3D fast activity inside the tissue. In the area of cardiac electrophysiology, the arrhythmia is caused by abnormal electrical propagation in the cardiac tissue and the recent simulation studies have reported that the complicated propagation in the cardiac tissue is generated during arrhythmia. Recently, laminar optical tomography has developed for measuring 3D activity in the tissue; however, the measuring speed is not enough to record the arrhythmia.
Then, we proposed the new system which can measure in parallel and reconstruct the 3D data from fewer measurements. This system can irradiate the excitation light as various patterns using Digital Micromirror Device and is combined with compressive sensing. By combining the parallel measuring and compressive sensing, this system can measure several hundred times faster than the conventional method, though the recording speed depends on the detector performance. From the simulation experiment results, the rough 3D data can be reconstructed from several measured images and the high and low potential region can be discriminated.
This system can be extended to the multiwavelength measuring because the compressive sensing is used and there is a room for compressing the data. The unknown knowledge between the action potential and calcium ion in the cardiac tissue during arrhythmia may be made clear in the future.