A 32-channel time-resolved instrument for medical optical tomography

A prototype multichannel time-resolved medical optical tomography system is presented, and various instrumental aspects and performance issues are discussed. The instrument has been designed primarily as a continuous bedside monitor for obtaining functional images of premature infants' brains that are at an increased risk of injury due to dysfunction in cerebral oxygenation or hemodynamics. Separate maps of the internal absorption and scattering properties can be reconstructed from purely temporal measurements of photons transmitted diffusely through the tissue, and without recourse to reference or baseline measurements. The instrument employs 32 source fibers that sequentially deliver near-infrared pulsed laser radiation of picosecond duration. Transit time measurements of very high temporal resolution and stability are made between these sources and 32 detector optodes that are located on the surface. The effectiveness of this instrument is demonstrated by successfully imaging a tissue-equivalent phantom. (C) 2000 American Institute of Physics. [S0034-6748(00)02001-3].