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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

Comparison of estimated temperature elevation with and without 3-D artificial physiological motion.Temperature elevation measured for the 3-D diagonal motion with a total displacement of (A) 5.2 mm, (B) 6.9 mm, and (C) 8.7 mm. For all three measurements, HIFU was applied between t = 10 s and t = 40 s. (D) Lower temperature values are associated with out-of-plane periodicity as the probe moves away from the focal spot. A movie of the strain-based temperature map superimposed on the B-mode image in the presence of 3-D diagonal motion is provided in the supplementary materials (S3 Movie).
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pone.0134938.g007: Comparison of estimated temperature elevation with and without 3-D artificial physiological motion.Temperature elevation measured for the 3-D diagonal motion with a total displacement of (A) 5.2 mm, (B) 6.9 mm, and (C) 8.7 mm. For all three measurements, HIFU was applied between t = 10 s and t = 40 s. (D) Lower temperature values are associated with out-of-plane periodicity as the probe moves away from the focal spot. A movie of the strain-based temperature map superimposed on the B-mode image in the presence of 3-D diagonal motion is provided in the supplementary materials (S3 Movie).

Mentions: Lastly, the results for 3-D motion are presented in Fig 7A, 7B and 7C. Compared to the previous 1-D and 2-D motion, cyclic oscillations are clearly observed in the temperature estimation resulting from the back and forth motion of the probe as summarized in Fig 7D. As the probe undergoes motion, the imaging plane was moved away from the heated region (fixed in space) and the temperature elevation decreased accordingly. The upper bound of the curve followed the temperature estimated when the imaging array was right above the focal spot while the lower bound followed the temperature estimated when the imaging array was at the most distant point in elevation (along y axis). Thus higher out-of-plane displacement led to greater temperature oscillations. This result shows that the temperature estimation is able to track the out-of-plane motion. Without heating, the RMSE generated by the 3-D motion was estimated to be 0.08°C, 0.10°C and 0.11°C for a total displacement of 5.2, 6.9 and 8.7 mm, respectively.


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 3-D artificial physiological motion.Temperature elevation measured for the 3-D diagonal motion with a total displacement of (A) 5.2 mm, (B) 6.9 mm, and (C) 8.7 mm. For all three measurements, HIFU was applied between t = 10 s and t = 40 s. (D) Lower temperature values are associated with out-of-plane periodicity as the probe moves away from the focal spot. A movie of the strain-based temperature map superimposed on the B-mode image in the presence of 3-D diagonal motion is provided in the supplementary materials (S3 Movie).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134938.g007: Comparison of estimated temperature elevation with and without 3-D artificial physiological motion.Temperature elevation measured for the 3-D diagonal motion with a total displacement of (A) 5.2 mm, (B) 6.9 mm, and (C) 8.7 mm. For all three measurements, HIFU was applied between t = 10 s and t = 40 s. (D) Lower temperature values are associated with out-of-plane periodicity as the probe moves away from the focal spot. A movie of the strain-based temperature map superimposed on the B-mode image in the presence of 3-D diagonal motion is provided in the supplementary materials (S3 Movie).
Mentions: Lastly, the results for 3-D motion are presented in Fig 7A, 7B and 7C. Compared to the previous 1-D and 2-D motion, cyclic oscillations are clearly observed in the temperature estimation resulting from the back and forth motion of the probe as summarized in Fig 7D. As the probe undergoes motion, the imaging plane was moved away from the heated region (fixed in space) and the temperature elevation decreased accordingly. The upper bound of the curve followed the temperature estimated when the imaging array was right above the focal spot while the lower bound followed the temperature estimated when the imaging array was at the most distant point in elevation (along y axis). Thus higher out-of-plane displacement led to greater temperature oscillations. This result shows that the temperature estimation is able to track the out-of-plane motion. Without heating, the RMSE generated by the 3-D motion was estimated to be 0.08°C, 0.10°C and 0.11°C for a total displacement of 5.2, 6.9 and 8.7 mm, respectively.

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