HIFU Pulsing Protocol for Predictable Tissue Emulsification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current high intensity focused ultrasound (HIFU) treatments for tissue ablation face challenges in reliability, predictability, and consistency due to stochastic cavitation, requiring high peak negative pressures and resulting in unpredictable tissue emulsification and thermal coagulation.
Innovation Solution
A HIFU pulsing protocol that generates shock waves with millisecond boiling, using peak positive pressures, ultrasound frequency, pulse repetition frequency, and duty cycle to induce mechanical fractionation of tissue with minimal thermal effects, and includes systems to detect boiling and differentiate mechanical from thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high peak negative pressures are used to induce cavitation for tissue emulsification, then mechanical disruption of tissue is achieved, but the treatment becomes unpredictable and difficult to reproduce
Solution Approach 1:
The patent changes the key parameter from peak negative pressure to peak positive pressure. By using peak positive pressures in the range of 2-20 MPa (compared to -20 MPa negative pressures), the treatment achieves predictable mechanical tissue disruption without requiring extremely high pressure levels, thereby improving reliability while reducing device complexity requirements
Solution Approach 2:
The patent employs periodic pulsed ultrasound delivery with duty cycles of 1-10% and pulse repetition frequencies of 1-100 Hz. This periodic action allows mechanical tissue disruption while providing cooling intervals that prevent thermal coagulation, making the treatment more predictable and controllable compared to continuous high-pressure exposure
2Reliability
If large aperture transducers with high focusing angles are used to achieve high peak negative pressures, then cavitation cloud formation is possible, but the device complexity and power output requirements increase
Solution Approach 1:
The patent inverts the pressure approach by using peak positive pressures instead of peak negative pressures. This parameter change allows the use of smaller aperture transducers with lower focusing angles, as the positive pressure shocks directly mechanically disrupt tissue without requiring the extreme negative pressure conditions that necessitate large, complex transducer systems
Solution Approach 2:
The patent inverts the conventional cavitation approach by using positive pressure shocks rather than negative pressure cavitation. This inversion eliminates the need for large aperture transducers and high power output capabilities, as the positive pressure mechanism achieves tissue disruption through a different physical pathway that is less demanding on transducer specifications
3Productivity
If continuous-wave HIFU exposure is used for tissue ablation, then thermal coagulation occurs, but surrounding tissue suffers undesirable thermal effects
Solution Approach 1:
The patent uses periodic pulsed ultrasound delivery with low duty cycles (1-10%) instead of continuous-wave exposure. The pulses are delivered at repetition frequencies of 1-100 Hz with durations of 10-1000 microseconds, providing mechanical tissue disruption during the pulse while allowing thermal dissipation during the off-period, thus achieving ablation efficiency without surrounding tissue thermal damage
Solution Approach 2:
The patent uses very short pulse durations (10-1000 microseconds) that are shorter than the thermal diffusion time constant of tissue. This allows the mechanical disruption to occur rapidly before heat can diffuse to surrounding tissues, effectively skipping the thermal damage phase and achieving productivity without harmful thermal side effects
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 protocol achieves repeatable, localizable, and predictable mechanical tissue destruction at lower pressure levels with minimal thermal coagulation, allowing for deeper penetration and controlled tissue emulsification.
Implementation Method 1
In several embodiments, for example, a HIFU pulsing protocol can generate shock waves at a target site that induce millisecond boiling to mechanically damage tissue with little to no thermal effect
Implementation Method 2
Histotripsy techniques, for example, can induce cavitation by delivering pulses of high peak negative pressures that are significantly higher than the tensile strength of the tissue
Implementation Method 3
HIFU thermal treatments increase the temperature of tissue at a focal region such that the tissue quickly forms a thermally coagulated treatment volume
Data Source
AI summary
Methods and systems for non-invasive treatment of tissue using high intensity focused ultrasound (“HIFU”) therapy. A method of non-invasively treating tissue in accordance with an embodiment of the present technology, for example, can include positioning a focal plane of an ultrasound source at a target site in tissue. The ultrasound source can be configured to emit HIFU waves. The method can further include pulsing ultrasound energy from the ultrasound source toward the target site, and generating shock waves in the tissue to induce boiling of the tissue at the target site within milliseconds. The boiling of the tissue at least substantially emulsifies the tissue.