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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

PID control of temperature elevation using strain-based temperature measurement.Comparison between requested temperature and strain-based temperature during PID control of hyperthermia (A) without motion and (B) in the presence of 2-D periodic motion with different displacements.
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pone.0134938.g009: PID control of temperature elevation using strain-based temperature measurement.Comparison between requested temperature and strain-based temperature during PID control of hyperthermia (A) without motion and (B) in the presence of 2-D periodic motion with different displacements.

Mentions: The 2-D motion pattern tested in the previous section was used to evaluate thermal strain as the feedback for a PID controller and was first tested without probe motion. As displayed in Fig 9A, tracking of the temperature was successfully achieved and temperature was maintained within 0.1°C of the requested +4°C increase in the steady-state. In this case, the standard deviation of the temperature was smaller than 0.1°C which demonstrates the high accuracy of the thermal strain estimation. The slow temperature rise was sufficient to smooth the system response and no oscillations were observed during the experiments. The 4 Hz framerate allowed a sufficient flow of feedback information for an accurate control of temperature. At the end the heating (t = 260 s), the magnitude of the correlation over the ROI reached a minimum value of 0.87 in relation with the thermal lens effect.


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)

PID control of temperature elevation using strain-based temperature measurement.Comparison between requested temperature and strain-based temperature during PID control of hyperthermia (A) without motion and (B) in the presence of 2-D periodic motion with different displacements.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134938.g009: PID control of temperature elevation using strain-based temperature measurement.Comparison between requested temperature and strain-based temperature during PID control of hyperthermia (A) without motion and (B) in the presence of 2-D periodic motion with different displacements.
Mentions: The 2-D motion pattern tested in the previous section was used to evaluate thermal strain as the feedback for a PID controller and was first tested without probe motion. As displayed in Fig 9A, tracking of the temperature was successfully achieved and temperature was maintained within 0.1°C of the requested +4°C increase in the steady-state. In this case, the standard deviation of the temperature was smaller than 0.1°C which demonstrates the high accuracy of the thermal strain estimation. The slow temperature rise was sufficient to smooth the system response and no oscillations were observed during the experiments. The 4 Hz framerate allowed a sufficient flow of feedback information for an accurate control of temperature. At the end the heating (t = 260 s), the magnitude of the correlation over the ROI reached a minimum value of 0.87 in relation with the thermal lens effect.

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