Visualization of cortical activation in human brain by flavoprotein fluorescence imaging

Area of Science:

• Neurosurgery
• Neuroscience
• Medical Imaging

Background:

• Conventional optical imaging methods like intraoperative perfusion-dependent imaging (iPDI) have limitations in visualizing rapid neural activity.
• Direct visualization of cortical activations is crucial for effective neuromonitoring during neurosurgery.

Purpose of the Study:

• To develop and evaluate intraoperative flavoprotein fluorescence imaging (iFFI) as an innovative method for real-time brain mapping and neuromonitoring in human neurosurgery.
• To compare the efficacy of iFFI with conventional iPDI in visualizing cortical activations.

Main Methods:

• iFFI and iPDI were performed on seven patients undergoing craniotomy for intracerebral tumors.
• A single operative microscope with a laser light source (iFFI) and xenon lamp (iPDI) was used, capturing images with the same camera.
• Cortical responses to bipolar stimulation were analyzed, with significant signal changes defined as exceeding 3 standard deviations from baseline.

Main Results:

• iFFI revealed biphasic signals (early positive F1, delayed negative F2) reflecting rapid cortical activity.
• iPDI showed a single delayed negative peak (P1), significantly later than F1 and overlapping with F2.
• F1 was more localized to the stimulus site compared to the widespread F2 and P1 signals, indicating faster neural responses.

Conclusions:

• iFFI successfully visualized rapid evoked cortical activity in humans during surgery for the first time.
• iFFI provides real-time insights into neural activation that precede perfusion-dependent signals.
• Further advancements in iFFI technology hold promise for its establishment as a critical intraoperative neuromonitoring tool.