Limits...
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

Comparison of estimated temperature elevation with and without artificial 1-D and 2-D physiological motion.(A) Axial compression in 1-D (ax. comp.), (B) in-plane diagonal motion (2-D) in the presence of a 4°C increase, and (C) in-plane diagonal motion (2-D) in presence of a 7°C increase. (D) Comparison of temperature estimation in presence of periodic 2-D motion (2-s period) and aperiodic motion. For the aperiodic motion, the displacement was diagonal and bounded to a maximum displacement of 7.1 mm but the speed and position was varied randomly during the motion. For all of the measurements, HIFU was applied between t = 10 s and t = 40 s. Movies of the strain-based temperature map superimposed on the B-mode image in the presence of axial compression and 2-D diagonal motion are provided in the supplementary materials S1 and S2 Movies, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4526517&req=5

pone.0134938.g006: Comparison of estimated temperature elevation with and without artificial 1-D and 2-D physiological motion.(A) Axial compression in 1-D (ax. comp.), (B) in-plane diagonal motion (2-D) in the presence of a 4°C increase, and (C) in-plane diagonal motion (2-D) in presence of a 7°C increase. (D) Comparison of temperature estimation in presence of periodic 2-D motion (2-s period) and aperiodic motion. For the aperiodic motion, the displacement was diagonal and bounded to a maximum displacement of 7.1 mm but the speed and position was varied randomly during the motion. For all of the measurements, HIFU was applied between t = 10 s and t = 40 s. Movies of the strain-based temperature map superimposed on the B-mode image in the presence of axial compression and 2-D diagonal motion are provided in the supplementary materials S1 and S2 Movies, respectively.

Mentions: An illustration of real-time temperature monitoring combining ultrasound imaging with a temperature map is given in Fig 5. The real-time display provides both spatial and temporal information regarding the temperature distribution. Tracking the center of the heated region gives the estimated temperature elevation as a function of time which is displayed in Fig 6. Temperature was averaged over a ROI of 3λ×3λ (0.9×0.9 mm2). Movies of the associated sequences are provided in the supplementary materials S1, S2 and S3 Movies. For all measurements in the presence of motion, a high correlation was obtained with the reference measurement with a clear separation between the heating and cooling phases. Differences between the experiments result from the deformation of the phantom (axial compression) or the motion of the imaging array (3-D motion).


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)

Comparison of estimated temperature elevation with and without artificial 1-D and 2-D physiological motion.(A) Axial compression in 1-D (ax. comp.), (B) in-plane diagonal motion (2-D) in the presence of a 4°C increase, and (C) in-plane diagonal motion (2-D) in presence of a 7°C increase. (D) Comparison of temperature estimation in presence of periodic 2-D motion (2-s period) and aperiodic motion. For the aperiodic motion, the displacement was diagonal and bounded to a maximum displacement of 7.1 mm but the speed and position was varied randomly during the motion. For all of the measurements, HIFU was applied between t = 10 s and t = 40 s. Movies of the strain-based temperature map superimposed on the B-mode image in the presence of axial compression and 2-D diagonal motion are provided in the supplementary materials S1 and S2 Movies, respectively.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134938.g006: Comparison of estimated temperature elevation with and without artificial 1-D and 2-D physiological motion.(A) Axial compression in 1-D (ax. comp.), (B) in-plane diagonal motion (2-D) in the presence of a 4°C increase, and (C) in-plane diagonal motion (2-D) in presence of a 7°C increase. (D) Comparison of temperature estimation in presence of periodic 2-D motion (2-s period) and aperiodic motion. For the aperiodic motion, the displacement was diagonal and bounded to a maximum displacement of 7.1 mm but the speed and position was varied randomly during the motion. For all of the measurements, HIFU was applied between t = 10 s and t = 40 s. Movies of the strain-based temperature map superimposed on the B-mode image in the presence of axial compression and 2-D diagonal motion are provided in the supplementary materials S1 and S2 Movies, respectively.
Mentions: An illustration of real-time temperature monitoring combining ultrasound imaging with a temperature map is given in Fig 5. The real-time display provides both spatial and temporal information regarding the temperature distribution. Tracking the center of the heated region gives the estimated temperature elevation as a function of time which is displayed in Fig 6. Temperature was averaged over a ROI of 3λ×3λ (0.9×0.9 mm2). Movies of the associated sequences are provided in the supplementary materials S1, S2 and S3 Movies. For all measurements in the presence of motion, a high correlation was obtained with the reference measurement with a clear separation between the heating and cooling phases. Differences between the experiments result from the deformation of the phantom (axial compression) or the motion of the imaging array (3-D motion).

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