Comparison of Compressional and Elastic Transcranial Photoacoustic Simulations for Presurgical Planning

Patient simulations can be a powerful tool to plan placement of photoacoustic imaging components for surgical guidance. This work uses compressional and elastic wave simulations to investigate each simulation method's influence on transcranial photoacoustic image quality. Compressional and elastic photoacoustick Wave simulations were performed based on a CT volume of a human cadaver head. Photoacoustic targets were placed in the locations of the internal carotid arteries and surgical instruments. An ultrasound transducer received signals from three acoustic windows (the ocular region, nasal cavity, and temporal region). Target visibility, target size estimates, and target-to-instrument distances were measured using contrast, resolution, and relative source distances, respectively, for each simulation method. Target contrast differences between images created with compressional and elastic simulations were at most 1.15 dB in nasal cavity. The largest lateral resolution difference between simulation types was 1.27 mm for the nasal cavity. Axial resolution and target-to-instrument distance differed by at most 0.02 mm and 0.07 mm between simulation types, respectively. Therefore, less time-consuming and less memory-intensive compressional-wave-only simulations would likely be sufficient to predict target visibility and target-to-instrument distances from transcranial photoacoustic images, while computationally heavy elastic wave simulations may be necessary to determine true target sizes with sub-millimeter accuracy.