User:LauraMorchi/sandbox

Image-guidance

HIFU therapy requires careful monitoring and so is usually performed in conjunction with other imaging techniques.

Pre-operative imaging, for instance CT and MRI, are usually used to identify general parameters of the target anatomy. Real-time imaging, on the other hand, is necessary for safe and accurate noninvasive targeting and therapy monitoring. Both MRI and Medical ultrasound imaging have been used for guidance in FUS treatment. These techniques are known as Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) and Ultrasound guided Focused Ultrasound Surgery (USgFUS) respectively . MRgFUS is a 3D imaging technique which features high soft tissue contrast and provides information about temperature, thus allowing to monitor ablation. However, low frame rate makes this technique perform poorly in real-time imaging and high costs represent a significant limitation to its use . USgFUS, differently, is a 2D imaging technique in which, although no system to provide quantitative information on temperature has been commercially developed so far, several benefits are exploited, such as high frame rate (up to 1000 images per second), low cost and minimal adverse health effects. In addition, treatment outcomes can be estimated in real time through visual inspection of hyperechoic changes in standard B-mode images . Being MRgFUS a high-cost, labor intensive and slow imaging technique, recently, research groups are putting more efforts in improving USgFUS technology. In the early clinical USgFUS platforms, the patient is reclined on the treatment table, partially immersed in water through which the treatment is delivered. This configuration guarantees an adequate acoustic coupling between the transducer and the patient’s body during the entire duration of the therapy . However, being the transducer positioned under the operative table, the set-up lacks in flexibility, thus limiting the surgeon’s ability in terms of intervention planning, and diminishing possible treatable areas. To overcome these limits, alternative solutions have been investigated and proposed. In particuar, in some solutions, the transducer is attached to a mechanical arm so as to be nimbly moved either manually or using a software control for accurate positioning with respect to the therapy target. A liquid-filled balloon is often interposed between the transducer and the patient as an acoustic coupling system to ensure the efficiency of the therapy. Examples of platforms adopting this approach include manually manipulated arms, like the commercial Echopulse by Theraclion (Malakoff, France) , used in applications like breast and thyroid treatment, and robotic research platforms in which a precise and accurate positioning of the mechanical arm is achieved through computer control, like the FUTURA platform . The concept behind this latter robotic approach is also known as computer-assisted surgery.