Laser Doppler imaging for intraoperative human brain mapping

Abstract

The identification and accurate location of centers of brain activity are vital both in neuro-surgery and brain research. This study aimed to provide a non-invasive, non-contact, accurate, rapid and user-friendly means of producing functional images intraoperatively. To this end a full field Laser Doppler imager was developed and integrated within the surgical microscope and perfusion images of the cortical surface were acquired during awake surgery whilst the patient performed a predetermined task. The regions of brain activity showed a clear signal (10-20% with respect to the baseline) related to the stimulation protocol which lead to intraoperative functional brain maps of strong statistical significance and which correlate well with the preoperative fMRI and intraoperative cortical electro-stimulation. These initial results achieved with a prototype device and wavelet based regressor analysis (the hemodynamic response function being derived from MRI applications) demonstrate the feasibility of LDI as an appropriate technique for intraoperative functional brain imaging.

See the Brain at Work — Intraoperative Laser Doppler Functional Brain Imaging

“…Finally, in (c), we show the full area of the craniotomy and the corresponding MRI Mercator representation with fMRI activations (white) for a finger tapping task. The region correlates well with that detected by LDI [11]. …”

Intraoperative optical imaging of intrinsic signals: a reliable method for visualizing stimulated functional brain areas during surgery

“…11,17,22 By use of a wide field laser Doppler imaging setup mounted to a neurosurgical microscope, changes in the perfusion of the cortex caused by finger tapping in an awake patient have been demonstrated. 22 In a few patients, the feasibility of imaging general brain perfusion by using laser speckle imaging was also shown.…”

“…11,17,22 By use of a wide field laser Doppler imaging setup mounted to a neurosurgical microscope, changes in the perfusion of the cortex caused by finger tapping in an awake patient have been demonstrated. 22 In a few patients, the feasibility of imaging general brain perfusion by using laser speckle imaging was also shown. 11,17 However, both methods need an additional laser source integrated into the surgical microscope, which increases complexity of the imaging setup and requires additional expenditure for the medical approval by regulatory boards.…”

Early monitoring of cerebral hypoperfusion in rats by laser speckle imaging and functional photoacoustic microscopy

“…Besides high time resolution, high spatial resolution and the capacity of 3D image make our method especially preponderant in early detection of cerebral hypoperfusion. Other potential applications in cerebrovascular diseases are immeasurable, such as intraoperative monitoring and post-treatment therapeutic efficacy evaluation in brain vascular malformations or brain aneurysm, 50 guidance for precise excision of the micro infarct tissues in brain ischemia, etc. 51 Although all the measurements are from the cerebral cortex, many studies manifest that there are significant changes in blood velocity and oxygen metabolism in cerebral cortex induced by cerebral hypoperfusion.…”