A heat flow approach to functional infrared thermography

Area of Science:

• Neuroscience
• Medical Imaging
• Surgical Technology

Background:

• Functional infrared thermography (fIRTH) is a noncontact method for intraoperative brain mapping.
• It relies on neurovascular coupling to detect temperature changes in activated cortical areas.
• Current analysis methods using absolute temperature are inconsistent indicators of brain activity.

Purpose of the Study:

• To compare the efficacy of analyzing fIRTH data using heat flow (time derivative of temperature) versus local heating (absolute temperature).
• To determine if heat flow analysis improves the accuracy of intraoperative functional brain mapping.

Main Methods:

• Developed functional maps using both local heating and local heat flow approaches.
• Calculated a group thermal response function and correlated it to cortical surface ROIs.
• Assessed map validity against direct electrical stimulation, the clinical gold standard.

Main Results:

• Heat flow analysis showed significant improvement for face motor mapping (ROC-AUC 0.89 vs 0.68) and marginal improvement for hand motor mapping (ROC-AUC 0.96 vs 0.93).
• Both methods were similarly inconsistent for hand sensory area identification (ROC-AUC ~0.69).
• Heat flow approach reduced activation artifacts outside stimulation sites.

Conclusions:

• Analyzing fIRTH data with the temporal derivative (heat flow) is crucial for long-block designs.
• This method enhances the reliability of brain activity indicators.
• Improved analysis is essential for establishing fIRTH as a robust brain mapping technique.