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Focused ultrasound therapy

When ultrasound is focused in a small volume of tissue, absorption of acoustical energy results in localized heating and elevation of temperature, which can be utilized to achieve therapeutic effects. The approach is often referred to as high-intensity focused ultrasound (HIFU), or focused ultrasound (FUS). In addition to thermal mechanisms, bioeffects can also be achieved in mechanical manner e.g. by using ultrasound in combination with cavitating ultrasound bubbles.

In a typical treatment setting, a phased array, composed of multiple ultrasonic transducers, is driven such that the ultrasound waves emitted from the device form a millimeter scale focus in a prescribed position in a patient. Since the ultrasound is delivered from outside the patient through an intact skin into the target, the technique has been referred to as bloodless surgery. During the ultrasound treatment sonications, the patient is monitored using e.g. magnetic resonance imaging (MRI) based thermometry, and ultrasound imaging based cavitation monitoring or mapping.

Some of the applications of focused ultrasound therapy under research or clinical use include:

• Transcranial focused ultrasound for functional neurosurgery
• Transient blood-brain barrier opening and targeted drug delivery
• Neuromodulation or neurostimulation

Main lines of research in ultrasound therapy in the group are:

• Development of tools for treatment planning
• Optimization of the treatment delivery
• Methodology research on ultrasound

Seniors working on ultrasound/contact person

• Aki Pulkkinen

Past and present collaborators

• Focused ultrasound group / professor Kullervo Hynynen, Sunnybrook Research Institute, Canada

Publications

1. A. Hughes, Y. Huang, A. Pulkkinen, M. L. Scwartz, A. M. Lozano, and K. Hynynen
   A numerical study on the oblique focus in MR-guided transcranial focused ultrasound
   Physics in Medicine and Biology 61 (22): 8025-8043 (2016)

2. A. Pulkkinen, B. Werner, E. Martin, and K. Hynynen
   Numerical simulations of clinical focused ultrasound functional neurosurgery
   Physics in Medicine and Biology 59 (7): 1679-1700 (2014)

3. J. Song, A. Pulkkinen, Y. Huang, and K. Hynynen
   Investigation of Standing-Wave Formation in a Human Skull for a Clinical Prototype of a Large-Aperture, Transcranial MR-Guided Focused Ultrasound (MRgFUS) Phased Array: An Experimental and Simulation Study
   IEEE Transactions on Biomedical Engineering 59 (2): 435-444 (2012)

4. N. Ellens, A. Pulkkinen, J. Song, and K. Hynynen
   The utility of sparse 2D fully electronically steerable focused ultrasound phased arrays for thermal surgery: a simulation study
   Physics in Medicine and Biology 56 (15): 4913-4932 (2011)

5. A. Pulkkinen, Y. Huang, J. Song, and K. Hynynen
   Simulations and measurements of transcranial low-frequency ultrasound therapy: skull-base heating and effective area of treatment
   Physics in Medicine and Biology 56 (15): 4661-4683 (2011)

6. A. Pulkkinen, and K. Hynynen
   Computational aspects in high intensity ultrasonic surgery planning
   Computerized Medical Imaging and Graphics 34 (1): 69-78 (2010)

Earlier publications

1. J. Huttunen, M. Malinen, T. Huttunen and J. P. Kaipio
   Determination of heterogenous thermal parameters using ultrasound induced heating and MR thermal mapping
   Physics in Medicine and Biology, 51, 1011-1032, 2006.

2. M. Malinen, S. R. Duncan, T. Huttunen, and J. P. Kaipio
   Feedforward and feedback control of ultrasound surgery
   Applied Numerical Mathematics, 56, 55-79, 2006.

3. T. Huttunen, M. Malinen J. P. Kaipio, P. J. White and K. Hynynen
   A full-wave Helmholtz model for continuous-wave ultrasound transmission
   IEEE Transactions in Ultrasonics, Felloelectric and Frequency Control, 52(3), 397-409, 2005.

4. M. Malinen, T. Huttunen, J. P. Kaipio and K. Hynynen
   Scanning path optimization for ultrasound surgery
   Physics in Medicine and Biology, 50,3473-3490, 2005.

5. M. Malinen, T. Huttunen, Hynynen, K. and J. P. Kaipio
   A model-based thermal dose optimization method for ultrasound surgery of the breast
   Medical Physics, 5, 1296-1307, 2004.

6. T. Huttunen, J. P. Kaipio and K. Hynynen
   Modeling of anomalies due to hydrophones in continuous-wave ultrasound fields
   IEEE Transactions in Ultrasonics, Ferroelectric and Frequency Control, 50(11), 1486-1500, 2003.

7. M. Malinen, T. Huttunen and J. P. Kaipio
   An optimal control approach for ultrasound induced heating
   International Journal of Control, 76, 1323-1336, 2003.

8. M. Malinen, T. Huttunen and J. P. Kaipio
   Thermal dose optimization method for ultrasound surgery
   Physics in Medicine and Biology, 48, 745-762, 2003.