Interleave-Sampled Photoacoustic Imaging for High-Frequency Resolution
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Solution Overview
Problem
High-frequency photoacoustic tomography is limited by the high cost and hardware requirements of ultrasound data acquisition systems with high sampling rates, and lower sampling rates in clinical ultrasound DAQs negatively impact high-frequency imaging resolution.
Innovation Solution
An interleave-sampled PA imaging technique that modulates the temporal offset of light pulses relative to sampling time, effectively doubling the sampling rate without requiring complex DAQ circuits, allowing high-frequency imaging with a relatively low sampling rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high sampling rate (>60 MHz) is used to capture high-frequency PA signals, then the imaging resolution is improved, but the hardware cost and system complexity increase significantly
Solution Approach 1:
The patent divides the sampling process into multiple segments by using multiple acquisitions at a lower sampling rate. Each acquisition captures a portion of the high-frequency signal, and these segments are then combined through interpolation to reconstruct the complete high-frequency signal, achieving equivalent resolution to a single high-rate acquisition without the associated hardware complexity
Solution Approach 2:
The patent performs preliminary low-rate acquisitions that capture sufficient signal information, then applies digital signal processing (interpolation) to preliminarily reconstruct the high-frequency content before final image formation, avoiding the need for expensive high-rate hardware from the outset
2Device complexity
If a low sampling rate (e.g., 32-60 MHz) is used to reduce hardware cost, then the system complexity is reduced, but the ability to capture high-frequency signals above the Nyquist limit is lost
Solution Approach 1:
The patent introduces digital interpolation as an intermediary process between the low-rate acquisition and the final high-frequency reconstruction. This intermediary algorithm fills in the missing high-frequency information that would otherwise be lost, effectively mediating between the limited hardware capabilities and the desired high-frequency signal capture
Solution Approach 2:
The patent changes the temporal sampling parameter by performing multiple acquisitions with different time offsets or phases. By varying the sampling timing parameters across acquisitions and combining them through interpolation, the system recovers high-frequency information that any single low-rate acquisition would miss
3Measurement precision
If multiple acquisitions are performed to double the effective sampling rate, then the sampling resolution is improved, but the frame rate is reduced by a factor of two
Solution Approach 1:
The patent employs periodic acquisitions at a lower rate, where multiple periodic cycles are performed with specific temporal offsets. This periodic structure allows the use of interpolation algorithms to combine the periodic data sets, achieving an effective sampling rate doubling while managing the frame rate reduction through efficient processing of the periodic acquisitions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The technique achieves higher axial and lateral resolution, capturing high-frequency information and improving signal-to-noise ratio, as demonstrated by both phantom and in vivo studies, while reducing the need for expensive hardware.
Implementation Method 1
a plurality of light pulses is generated that cause ultrasonic emission from the sample
Data Source
AI summary
In accordance with a method of obtaining at least one photoacoustic (PA) image of a sample, a plurality of light pulses is generated that cause ultrasonic emission from the sample. Ultrasonic emission signals from the sample caused by each of the light pulses are received. The ultrasonic emission signals are sampled to obtain sampled data values. A time duration between a time at which the light pulses are generated and a time at which the sampling of the ultrasonic emission signals is performed is modulated. At least one photoacoustic image of the sample is reconstructed from the sampled data values of the ultrasonic emission signals.