Ultrasound Transducer Mapping via MR-ARFI
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Solution Overview
Problem
Existing methods for mapping phased-array ultrasound transducers are limited by the need for auxiliary equipment and reduced power levels during calibration, which can undermine the validity of adjustments and lead to improper focus location and reduced therapy effectiveness.
Innovation Solution
The method involves generating an ultrasound focus in a phantom and using magnetic-resonance acoustic radiation force imaging (MR-ARFI) to measure and optimize focus quality by adjusting phase and amplitude settings of transducer elements, allowing for calibration at normal operational power levels without explicit determination of element locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional hydrophone-based mapping methods are used, then transducer element locations can be measured, but additional auxiliary equipment is required and mapping must be performed at reduced power levels which undermines adjustment validity
Solution Approach 1:
The transducer array maps itself by using its own therapeutic ultrasound beams to generate acoustic radiation force displacements in the patient's tissue. The MR imaging system detects these self-generated displacements, eliminating the need for external hydrophones or auxiliary mapping equipment. The system serves its own mapping function through its therapeutic operation.
Solution Approach 2:
MR acoustic radiation force imaging (MR-ARFI) serves as an intermediary measurement technique that can detect tissue displacements caused by ultrasound at full therapeutic power levels. This intermediary method replaces the traditional hydrophone-based measurement system, enabling both accurate location measurement and full-power operation compatibility.
2Reliability
If mapping is performed at reduced power levels to protect hydrophone, then transducer locations can be measured, but the validity of adjustments under therapeutic conditions is undermined
Solution Approach 1:
MR-ARFI imaging acts as an intermediary measurement system that can withstand full therapeutic ultrasound power levels without damage. Unlike hydrophones that require reduced power protection, the MR imaging system safely measures tissue displacements even at maximum therapeutic intensities, ensuring adjustment validity is maintained under actual therapeutic conditions.
Solution Approach 2:
The patent replaces the mechanical hydrophone measurement system with an MR imaging-based displacement detection system. This substitution eliminates the power level limitation imposed by hydrophone fragility, allowing mapping to be performed at full therapeutic power levels where the actual therapeutic effects occur.
3Loss of information
If explicit determination of transducer element locations is performed using triangulation, then element positions can be calculated, but additional auxiliary equipment and complex procedures are required
Solution Approach 1:
The system determines transducer element locations by measuring the acoustic radiation force displacements they directly generate in the patient's tissue during normal operation. Each element's location is inferred from its own therapeutic beam's effect on tissue, eliminating the need for external measurement devices and complex triangulation procedures.
Solution Approach 2:
The patent replaces the acoustic triangulation measurement system with an MR imaging displacement detection system. Instead of using hydrophones and time-of-flight measurements to calculate locations, the system directly images the tissue displacements caused by each element's therapeutic beam, simplifying the mapping procedure and eliminating auxiliary equipment requirements.
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
This approach improves focus quality by maximizing intensity and displacement in the phantom, reducing the need for additional equipment and ensuring accurate adjustments for better therapeutic outcomes.
Implementation Method 1
driving the plurality of transducer elements so as to generate an ultrasound focus
Implementation Method 2
measuring a displacement associated with the focus by ARFI
Implementation Method 3
using magnetic-resonance acoustic radiation force imaging (MR-ARFI) to measure and optimize focus quality
Data Source
AI summary
Ultrasound transducers may be mapped by varying a focus-affecting parameter and adjusting the parameter so as to improve focus quality. In some embodiments, mapping involves successively varying the phase of one transducer element, or group of elements, with respect to a constant phase of the other transducer elements, and determining the phase at which a tissue displacement in the ultrasound focus is maximized.