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Spatial and Temporal Control of Hyperthermia Using Real Time Ultrasonic Thermal Strain Imaging with Motion Compensation, Phantom Study.

Foiret J, Ferrara KW - PLoS ONE (2015)

Bottom Line: However, combined ultrasound imaging and therapy systems offer the benefits of simple, low-cost devices that can be broadly applied.Here, we propose a motion compensation method based on the acquisition of multiple reference frames prior to treatment.The technique was tested in the presence of 2-D and 3-D physiological-scale motion and was found to provide effective real-time temperature monitoring.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, United States of America.

ABSTRACT
Mild hyperthermia has been successfully employed to induce reversible physiological changes that can directly treat cancer and enhance local drug delivery. In this approach, temperature monitoring is essential to avoid undesirable biological effects that result from thermal damage. For thermal therapies, Magnetic Resonance Imaging (MRI) has been employed to control real-time Focused Ultrasound (FUS) therapies. However, combined ultrasound imaging and therapy systems offer the benefits of simple, low-cost devices that can be broadly applied. To facilitate such technology, ultrasound thermometry has potential to reliably monitor temperature. Control of mild hyperthermia was previously achieved using a proportional-integral-derivative (PID) controller based on thermocouple measurements. Despite accurate temporal control of heating, this method is limited by the single position at which the temperature is measured. Ultrasound thermometry techniques based on exploiting the thermal dependence of acoustic parameters (such as longitudinal velocity) can be extended to create thermal maps and allow an accurate monitoring of temperature with good spatial resolution. However, in vivo applications of this technique have not been fully developed due to the high sensitivity to tissue motion. Here, we propose a motion compensation method based on the acquisition of multiple reference frames prior to treatment. The technique was tested in the presence of 2-D and 3-D physiological-scale motion and was found to provide effective real-time temperature monitoring. PID control of mild hyperthermia in presence of motion was then tested with ultrasound thermometry as feedback and temperature was maintained within 0.3°C of the requested value.

No MeSH data available.


Related in: MedlinePlus

Experimental setup and tested artificial motions.(A) The diagnostic imaging array was placed above the tissue-mimicking phantom and physiological motion was simulated by moving the array using a 3-axis motorized stage. The single transducer element generating heat and the phantom were fixed. Ultrasound data were acquired on a programmable ultrasound system (Vantage 256, Verasonics) and processed and displayed in real-time using a dedicated computer. (B) Simulated cyclic motions: axial compression (1-D motion) and linear translations with in-plane (2-D motion) or out-of-plane displacement (3-D motion). Axial compression was generated by direct contact of the probe with the phantom.
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pone.0134938.g001: Experimental setup and tested artificial motions.(A) The diagnostic imaging array was placed above the tissue-mimicking phantom and physiological motion was simulated by moving the array using a 3-axis motorized stage. The single transducer element generating heat and the phantom were fixed. Ultrasound data were acquired on a programmable ultrasound system (Vantage 256, Verasonics) and processed and displayed in real-time using a dedicated computer. (B) Simulated cyclic motions: axial compression (1-D motion) and linear translations with in-plane (2-D motion) or out-of-plane displacement (3-D motion). Axial compression was generated by direct contact of the probe with the phantom.

Mentions: A 5 MHz single-element transducer (IL0508HP, Valpey-Fischer, MA) was used to generate heat in an agarose-based tissue mimicking phantom. A 5 MHz 128-element imaging array (L7-4, Philips ATL, WA) was placed above the phantom with the imaging plane perpendicular to the heating transducer beam axis as depicted in Fig 1A. Physiological motion was simulated by moving the probe with a 3-D linear motorized stage remotely activated by a motion controller (ESP300, Newport Corporation, Irvine, CA). The choice of moving the imaging array rather than the phantom was to mimic an ultrasound treatment with real-time motion correction of the HIFU beam to track the target [36]. In this scenario, the ultrasound-generated heat was independent of the motion which facilitates evaluation of the quality of the temperature estimates. Radio-Frequency (RF) data were acquired with an ultrasonic acquisition system (Vantage 256, Verasonics, Redmond, WA) at a sampling frequency of 20 MHz.


Spatial and Temporal Control of Hyperthermia Using Real Time Ultrasonic Thermal Strain Imaging with Motion Compensation, Phantom Study.

Foiret J, Ferrara KW - PLoS ONE (2015)

Experimental setup and tested artificial motions.(A) The diagnostic imaging array was placed above the tissue-mimicking phantom and physiological motion was simulated by moving the array using a 3-axis motorized stage. The single transducer element generating heat and the phantom were fixed. Ultrasound data were acquired on a programmable ultrasound system (Vantage 256, Verasonics) and processed and displayed in real-time using a dedicated computer. (B) Simulated cyclic motions: axial compression (1-D motion) and linear translations with in-plane (2-D motion) or out-of-plane displacement (3-D motion). Axial compression was generated by direct contact of the probe with the phantom.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526517&req=5

pone.0134938.g001: Experimental setup and tested artificial motions.(A) The diagnostic imaging array was placed above the tissue-mimicking phantom and physiological motion was simulated by moving the array using a 3-axis motorized stage. The single transducer element generating heat and the phantom were fixed. Ultrasound data were acquired on a programmable ultrasound system (Vantage 256, Verasonics) and processed and displayed in real-time using a dedicated computer. (B) Simulated cyclic motions: axial compression (1-D motion) and linear translations with in-plane (2-D motion) or out-of-plane displacement (3-D motion). Axial compression was generated by direct contact of the probe with the phantom.
Mentions: A 5 MHz single-element transducer (IL0508HP, Valpey-Fischer, MA) was used to generate heat in an agarose-based tissue mimicking phantom. A 5 MHz 128-element imaging array (L7-4, Philips ATL, WA) was placed above the phantom with the imaging plane perpendicular to the heating transducer beam axis as depicted in Fig 1A. Physiological motion was simulated by moving the probe with a 3-D linear motorized stage remotely activated by a motion controller (ESP300, Newport Corporation, Irvine, CA). The choice of moving the imaging array rather than the phantom was to mimic an ultrasound treatment with real-time motion correction of the HIFU beam to track the target [36]. In this scenario, the ultrasound-generated heat was independent of the motion which facilitates evaluation of the quality of the temperature estimates. Radio-Frequency (RF) data were acquired with an ultrasonic acquisition system (Vantage 256, Verasonics, Redmond, WA) at a sampling frequency of 20 MHz.

Bottom Line: However, combined ultrasound imaging and therapy systems offer the benefits of simple, low-cost devices that can be broadly applied.Here, we propose a motion compensation method based on the acquisition of multiple reference frames prior to treatment.The technique was tested in the presence of 2-D and 3-D physiological-scale motion and was found to provide effective real-time temperature monitoring.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, United States of America.

ABSTRACT
Mild hyperthermia has been successfully employed to induce reversible physiological changes that can directly treat cancer and enhance local drug delivery. In this approach, temperature monitoring is essential to avoid undesirable biological effects that result from thermal damage. For thermal therapies, Magnetic Resonance Imaging (MRI) has been employed to control real-time Focused Ultrasound (FUS) therapies. However, combined ultrasound imaging and therapy systems offer the benefits of simple, low-cost devices that can be broadly applied. To facilitate such technology, ultrasound thermometry has potential to reliably monitor temperature. Control of mild hyperthermia was previously achieved using a proportional-integral-derivative (PID) controller based on thermocouple measurements. Despite accurate temporal control of heating, this method is limited by the single position at which the temperature is measured. Ultrasound thermometry techniques based on exploiting the thermal dependence of acoustic parameters (such as longitudinal velocity) can be extended to create thermal maps and allow an accurate monitoring of temperature with good spatial resolution. However, in vivo applications of this technique have not been fully developed due to the high sensitivity to tissue motion. Here, we propose a motion compensation method based on the acquisition of multiple reference frames prior to treatment. The technique was tested in the presence of 2-D and 3-D physiological-scale motion and was found to provide effective real-time temperature monitoring. PID control of mild hyperthermia in presence of motion was then tested with ultrasound thermometry as feedback and temperature was maintained within 0.3°C of the requested value.

No MeSH data available.


Related in: MedlinePlus