Fast noninvasive functional diffuse optical tomography for brain imaging

Abstract

Advances in epilepsy studies have shown that specific changes in hemodynamics precede and accompany seizure onset and propagation. However, it has been challenging to noninvasively detect these changes in real time and in humans, due to the lack of fast functional neuroimaging tools. In this study, we present a functional diffuse optical tomography (DOT) method with the guidance of an anatomical human head atlas for 3-dimensionally mapping the brain in real time. Central to our DOT system is a human head interface coupled with a technique that can incorporate topological information of the brain surface into the DOT image reconstruction. The performance of the DOT system was tested by imaging motor tasks-involved brain activities on N = 6 subjects (3 epilepsy patients and 3 healthy controls). We observed diffuse areas of activations from the reconstructed [HbT] images of patients, relative to more focal activations for healthy subjects. Moreover, significant pretask hemodynamic activations were also seen in the motor cortex of patients, which indicated abnormal activities persistent in the brain of an epilepsy patient. This work demonstrates that fast functional DOT is a valuable tool for noninvasive 3-dimensional mapping of brain hemodynamics.

Cerebral hemodynamic responses in preterm-born neonates to visual stimulation: classification according to subgroups and analysis of frontotemporal–occipital functional connectivity

“…Covering the whole head with light sensors and detectors would be ideal since this would enable NIRS imaging (tomography) to be performed with the possibility to determine precisely the depth-resolved spatiotemporal changes of tissue oxygenation and hemodynamics. 74,75 Extending the fNIRS measured signals is another possibility for future fNIRS studies with preterm-born neonates. Especially measuring changes in the cytochrome-C-oxidase 76,77,78 with broadband NIRS (B-NIRS) may give additional information, in particular regarding the changes in cerebral metabolism elicited by the functional stimulation.…”

High-density diffuse optical tomography for imaging human brain function

“…3 uses LEDs emitting 750 nm and 850 nm photons with an optical power at the head of 3.2 ± 0.3 mW and 4.3 ± 0.3 mW for each LED 46 . Other systems have used different wavelength combinations including 760 and 830 nm (the DYNOT 232 optical tomography imager of NIRx 59 ), 690 and 830 nm (the ISS Imagent™ 157 and the CW4 TechEn, Inc. system 44 ), 660, 780 and 850, 158 and even a larger set of wavelengths including 778, 808, 814, 841, 847, 879, 888, and 898 nm 159,160 . The system in Figure 3 used three 750 nm LEDs per channel to compensate for the strong attenuation in biological tissue at that wavelength.…”

“… 26,46 Alternatively, a spring loaded fiber tip can couple fibers to the scalp 59 . Furthermore, rigid outer structures aid in fiber management and suspend the weight of the fibers 158 . Recent work has designed more wearable caps with lightweight fibers 167 .…”

High‐speed X‐ray‐induced luminescence computed tomography

“…XLCT imaging shows promising higher molecular sensitivity over conventional X-ray CT imaging while maintaining the higher spatial resolution of X-ray CT imaging. Moreover, compared to traditional light excited fluorescence imaging like fluorescence molecular tomography (FMT) [8][9][10][11][12][13][14][15] or pure optical imaging such as diffuse optical tomography (DOT) [16] and bioluminescence tomography (BLT) [17][18][19][20][21], XLCT has superb tissue penetration and less excitation light interference, allowing for whole-body molecular imaging in high spatial resolution.…”