Benchmark problems for transcranial ultrasound simulation: Intercomparison of compressional wave models

Area of Science:

• Acoustics
• Biomedical Engineering
• Computational Modeling

Background:

• Computational models of acoustic wave propagation are crucial for transcranial ultrasound (TUS) therapies, aiding in calculations for intracranial pressure and skull distortion correction.
• Standardized benchmarks are needed to enable intercomparison of diverse modeling tools and techniques within the research community.

Purpose of the Study:

• To establish a set of numerical benchmarks for acoustic wave propagation in transcranial ultrasound.
• To present intercomparison results from multiple computational modeling tools using these benchmarks.

Main Methods:

• Defined nine benchmarks of increasing geometric complexity, including single-layer bone, multi-layer bone, and whole skull models.
• Utilized two transducer configurations (focused bowl and plane piston at 500 kHz) across 18 benchmark permutations.
• Employed eleven distinct modeling tools representing various numerical techniques (FDTD, ASM, pseudospectral, BEM, SEM).

Main Results:

• Demonstrated good agreement among the eleven computational models, especially in predicting the acoustic focus's position, size, and magnitude within the skull.
• Achieved median differences of less than 10% for focal pressure and 1 mm for focal position in cross-comparisons between models.
• Found that benchmark definitions, results, and intercomparison codes are publicly available.

Conclusions:

• The established benchmarks provide a reliable framework for validating computational models of acoustic wave propagation for TUS.
• The intercomparison results confirm the general accuracy and consistency of various numerical methods used in the field.
• Availability of benchmark data promotes further development and standardization in TUS modeling.