Real‐time adaptive methods for treatment of mobile organs by MRI‐controlled high‐intensity focused ultrasound

Senneville, Baudouin Denis de; Mougenot, Charles; Moonen, Chrit

doi:10.1002/mrm.21124

Cited by 176 publications

(168 citation statements)

References 38 publications

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“…Phased-array transducers offer a very fast displacement of the focal point with 15 positions updated per second (for our in-house-designed HIFU system). Therefore, this volumetric heating temperature control may also be combined with motion tracking of the target region, as recently demonstrated (22). …”

Section: Discussionmentioning

confidence: 93%

Three‐dimensional spatial and temporal temperature control with MR thermometry‐guided focused ultrasound (MRgHIFU)

Mougenot

Quesson

Senneville

et al. 2008

Magnetic Resonance in Med

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128

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High-intensity focused ultrasound (HIFU) is an efficient noninvasive technique for local heating. Using MRI thermal maps, a proportional, integral, and derivative (PID) automatic temperature control was previously applied at the focal point, or at several points within a plane perpendicular to the beam axis using a multispiral focal point trajectory. This study presents a flexible and rapid method to extend the spatial PID temperature control to three dimensions during each MR dynamic. The temperature in the complete volume is regulated by taking into account the overlap effect of nearby sonication points, which tends to enlarge the heated area along the beam axis. Volumetric temperature control in vitro in gel and in vivo in rabbit leg muscle was shown to provide temperature control with a precision close to that of the temperature MRI measurements. High-intensity focused ultrasound (HIFU) is an efficient noninvasive technique to produce local heating deep inside the human body (1,2). MRI provides excellent visualization of anatomical structures and tumors for treatment planning (3). In addition, MRI can provide continuous temperature mapping based on the proton resonance frequency (PRF) shift of water with a good spatial and temporal resolution (4,5) for real-time therapy control. New MRI developments in high-field, rapid imaging and magnet field stability have contributed to the performance of MRI temperature mapping. In parallel, major improvement in ultrasound technology have been made in the field of phased-array MR-compatible transducers (6). These recent developments offer the possibility to treat several points simultaneously and in a minimal amount of time.Automatic control of the temperature (7) or the thermal dose effect (8) during HIFU heating has been shown to be feasible. Using rapid temperature MRI methods and realtime data processing, an automatic proportional, integral, and derivative (PID) temperature feedback loop has been presented to control the temperature in a single point, the HIFU focal spot (9). This temperature control method has been extended to several points (10) using a multispiral trajectory of the HIFU focal point within a single plane perpendicular to the beam axis. In the latter method, the energy deposition during the next multispiral trajectory is calculated upon completion of the previous one. The resulting volume treated in three dimensions is deduced from numerical simulations. The focal point trajectory remains in a plane perpendicular to the beam axis since the overlap of the acoustic field for each focal point location presents difficulties for volumetric temperature control along the beam axis.Here, a novel method is proposed for volumetric temperature regulation with temperature control for each voxel of the predefined volume by taking into account beam overlap for the different sonication points. The optimum focal point locations and HIFU intensities are determined following each volumetric temperature map, leading to a rapid and flexible method. The new method was ...

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Section: Discussionmentioning

confidence: 93%

Three‐dimensional spatial and temporal temperature control with MR thermometry‐guided focused ultrasound (MRgHIFU)

Mougenot

Quesson

Senneville

et al. 2008

Magnetic Resonance in Med

Self Cite

128

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“…No motion correction was necessary, as the temperature measurement was always performed at the same moment in the breathing cycle at the same organ position. Different from liver thermometry during focused ultrasound application, which has been reported to be difficult (29), a lower temporal and spatial resolution of the data may be sufficient for the sequential approach presented here.…”

Section: Discussionmentioning

confidence: 99%

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

Rempp

Clasen

Boss

et al. 2009

Magnetic Resonance Imaging

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Purpose:To assess the feasibility of magnetic resonance (MR) thermometry after thermoablative therapy and to quantitatively evaluate the ability of two sequence types to predict cell necrosis. Methods:Twenty patients with hepatic tumors were treated by MR-guided radiofrequency ablation. For each 10 patients, postinterventionally performed gradient echo and segmented echo planar imaging sequences were used to calculate temperature maps based on the proton resonance frequency shift method. Contrast-enhanced images acquired 1 month after therapy were registered on the temperature maps and the necrotic, nonenhanced area was segmented and compared to the area with a displayed temperature above 60°C. Sensitivity and positive predictive value of the temperature map was calculated, using the follow-up imaging as the gold standard. Results:Temperature mapping reached acceptable image quality in 45/47 cases. Sensitivity, ie, the rate of correctly detected coagulated tissue was 0.82 Ϯ 0.08 for the gradient echo imaging (GRE) sequence and 0.81 Ϯ 0.14 for the echo planar imaging (EPI) sequence. Positive predictive value, ie, the rate of voxel in the temperature map over 60°C that actually developed necrosis, was 0.90 Ϯ 0.07 for the GRE sequence and 0.84 Ϯ 0.11 for the EPI sequence. Conclusion:Sequential MR temperature mapping allows for the prediction of the coagulation zone with an acceptable sensitivity and positive predictive value using EPI and GRE sequences. REAL-TIME TEMPERATURE MAPPING of magnetic resonance (MR)-guided minimally invasive radiofrequency (RF) ablation has been shown to be feasible both ex vivo (1) and in vivo (2-5), and has the potential of becoming the gold standard for therapy monitoring of thermoablative therapies. Different MR techniques have been proposed for temperature measurement (6 -10); the most frequently used is the proton resonance frequency shift (PRF) method (11-14), which is based on a temperature-dependent phase shift allowing for the measurement of temperature changes relative to a baseline image. With frequent repetitive measurements during thermoablative therapy, this approach allows a precise estimation of the lethal thermal dose (15) based on the Arrhenius model (16,17) and could be used to predict the size and position of the coagulation zone in animal studies (3,5). Furthermore, real-time temperature monitoring could allow for visualizing a vessel-related cooling effect and thus prevent a survival of cancer cells due to an undetected heat-sink effect.Due to technical and medical challenges linked to this approach, the majority of the literature up to now concerns preclinical questions. In case of RF ablation, the simultaneous use of an RF generator with frequencies between 300 and 500 kHz during imaging decreases image quality (6,18). To date, only noncommercial filters were used to overcome this problem (4,18) or generators with an adapted frequency were employed in animal studies (3,19). Therefore, we performed temperature measurement with a sequential approach: The sedated pat...

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“…Ultimately, it would be desirable to be able to treat free-breathing awake patients. This may be possible using real-time motion tracking, perhaps using the ultrasound probe itself to track the motion (30), a phased array with a large steering range, and motioninsensitive MR thermometry schemes (31)(32)(33).…”

Section: Livermentioning

confidence: 99%

“…Such phased array devices will develop further to their full potential through the implementation of treatment plans that include beam aberration correction (80) and the optimization of thermal dose delivery (81). Fully automatic closed-loop feedback to control heating (40,57,81,82) combined with robust motion detection and correction schemes for the MR thermometry (31)(32)(33)83) will also likely reach the clinic for MRgFUS.…”

Section: Future Development Of Technologymentioning

confidence: 99%

Current status and future potential of MRI‐guided focused ultrasound surgery

Jólesz

McDannold

2008

Magnetic Resonance Imaging

112

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The combination of the imaging abilities of magnetic resonance imaging (MRI) with the ability to delivery energy to targets deep in the body noninvasively with focused ultrasound presents a disruptive technology with the potential to significantly affect healthcare. MRI offers precise targeting, visualization, and quantification of temperature changes and the ability to immediately evaluate the treatment. By exploiting different mechanisms, focused ultrasound offers a range of therapies, ranging from thermal ablation to targeted drug delivery. This article reviews recent preclinical and tests clinical of this technology. WHILE ITS POTENTIAL has been recognized for decades (1-4), focused ultrasound (FUS) therapy has been in the incubation phase for a long time. Although it has been tested in numerous animal experiments, its widespread clinical realization has lagged, primarily due to the lack of intraprocedural accurate temperature monitoring. When the idea of MRI-guidance was introduced in connection with FUS and MRI thermometry during sonication was demonstrated (5,6), it was anticipated that MR-guided FUS surgery (MRgFUS) would be widely accepted clinically within a few years. Despite these early expectations, there has been relatively slow progress in the clinical implementation of MRgFUS.Early development concentrated primarily on breast tumors (benign fibroadenoma (7,8) and malignant breast cancer (9,10)). These early implementations of the MRgFUS technology motivated the improvement of transducer technology from single-element transducers to MRI-compatible multielement phase arrays (11). There was also significant progress in MRI thermometry and its use to monitor and control sonications. Importantly, too, methods were developed to robustly quantify temperature changes (12). At first, only 2D temperature maps were obtained by MRI to allow for accurate targeting of the beam (13). Later these thermal images were used to generate maps of the thermal dose (14) that could then be used to tailor the energy deposition using closed-loop feedback control (15). This preclinical work led to the development of the first commercial system by InSightec (Haifa, Israel), the Exablate 2000, the first implementation of a fully integrated MRgFUS system that combined a phased array transducer, a computer-controlled robotic positioner, and a workstation that integrated control based on MR thermometry.The early limited clinical trials of breast tumor treatment (8 -10,16,17) were followed by the first major clinical application: the noninvasive therapy of benign uterine fibroids (18,19). The successful Phase I trial was followed by a multicenter . These clinical trials led to the approval of this technology for the treatment of uterine fibroids in several countries, including the United States. Examples of MR thermometry and postablation imaging of a uterine fibroid ablation are shown in Figure 1.The success of uterine fibroid ablation has invigorated the entire field. Technology has rapidly improved and clinical applications ke...

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Real‐time adaptive methods for treatment of mobile organs by MRI‐controlled high‐intensity focused ultrasound

Cited by 176 publications

References 38 publications

Three‐dimensional spatial and temporal temperature control with MR thermometry‐guided focused ultrasound (MRgHIFU)

Three‐dimensional spatial and temporal temperature control with MR thermometry‐guided focused ultrasound (MRgHIFU)

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

Current status and future potential of MRI‐guided focused ultrasound surgery

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