Rapid near-infrared diffuse tomography for hemodynamic imaging using a low-coherence wideband light source.
Rapid near-infrared (NIR) diffuse optical tomography is implemented using a low-coherence source. The spectral bandwidth of the low-coherence source is dispersed and coupled to linearly bundled fibers, such that "spread"-spectral encoding among the bundled fibers is formed, and could be used for parallel source illumination onto tissue. In comparison with a previous spectral-encoding technique that employed multiple laser diodes, the use of a low-coherence source for spread-spectral encoding presents a few unique characteristics: (1) it provides shift-free spectral encoding; (2) it reduces the reconstruction uncertainty significantly owing to the minimization of spontaneous channel-to-channel intensity fluctuation; and (3) it enables the implementation of NIR tomography into an endoscopic imaging mode. A 20-mW superluminescent diode centered at 840 nm with a 40-nm bandwidth is used as the source, and a sampling speed of 5 Hz is obtained in a 27-mm imaging array consisting of eight sources and eight detection channels. The principles of using a low-coherence source for spread-spectral encoding are elaborated, the characteristic performances are demonstrated, and the preliminary results of imaging hemoglobin absorption variations during 10 s of voluntary breath-holding are presented.
Piao
Daqing
D
Oklahoma State University, School of Electrical and Computer Engineering, Stillwater, Oklahoma 74078-5032, USA. daqing.piao@okstate.edu
Pogue
Brian W
BW
D003199:Computer Systems; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D008029:Lighting / Q000295:instrumentation* / Q000379:methods; D010092:Oximetry / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D017156:Photoplethysmography / Q000295:instrumentation* / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000295:instrumentation* / Q000379:methods; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods