Real‐time monitoring of radiofrequency ablation of rabbit liver by respiratory‐gated quantitative temperature MRI

Lepetit‐Coiffé, Matthieu; Quesson, Bruno; Séror, Olivier; Dumont, Erik; Bail, Brigitte Le; Moonen, Chrit; Trillaud, Hervé

doi:10.1002/jmri.20605

Cited by 58 publications

(68 citation statements)

References 24 publications

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“…Conventional respiratory gating in animals under general anesthesia and mechanical respiration (93) has been successfully used. Respiratory gating during free breathing has also been used (94), but gating can fail when the respiratory cycle is irregular, leading to motion artifacts and errors in the temperature maps (84). Others have described motion detection and movement registration with navigator echoes for displacements of ex vivo tissue (87).…”

Section: Prf Thermometry and Motionmentioning

confidence: 99%

MR thermometry

Rieke

Pauly

2008

Magnetic Resonance Imaging

1,019

952

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Minimally invasive thermal therapy as local treatment of benign and malignant diseases has received increasing interest in recent years. Safety and efficacy of the treatment require accurate temperature measurement throughout the thermal procedure. Noninvasive temperature monitoring is feasible with magnetic resonance (MR) imaging based on temperature-sensitive MR parameters such as the proton resonance frequency (PRF), the diffusion coefficient (D), T 1 and T 2 relaxation times, magnetization transfer, the proton density, as well as temperature-sensitive contrast agents. In this article the principles of temperature measurements with these methods are reviewed and their usefulness for monitoring in vivo procedures is discussed. Whereas most measurements give a temperature change relative to a baseline condition, temperature-sensitive contrast agents and spectroscopic imaging can provide absolute temperature measurements. The excellent linearity and temperature dependence of the PRF and its near independence of tissue type have made PRF-based phase mapping methods the preferred choice for many in vivo applications. Accelerated MRI imaging techniques for real-time monitoring with the PRF method are discussed. Special attention is paid to acquisition and reconstruction methods for reducing temperature measurement artifacts introduced by tissue motion, which is often unavoidable during in vivo applications.

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Section: Prf Thermometry and Motionmentioning

confidence: 99%

MR thermometry

Rieke

Pauly

2008

Magnetic Resonance Imaging

1,019

952

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“…However, not all patients may qualify for breath holds or general anesthesia, and the methods are not suitable for cardiac ablation. Conventional respiratory gating has been used under general anesthesia 8 and free breathing, 9 but gating can fail when the respiratory cycle is irregular, leading to motion artifacts and errors in the temperature maps. 10 Methods for temperature estimation in the presence of motion can be divided into two categories: methods based on a multibaseline strategy and methods based on a referenceless strategy.…”

Section: Introductionmentioning

confidence: 99%

Hybrid referenceless and multibaseline subtraction MR thermometry for monitoring thermal therapies in moving organs

et al. 2010

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Purpose: Magnetic resonance thermometry using the proton resonance frequency ͑PRF͒ shift is a promising technique for guiding thermal ablation. For temperature monitoring in moving organs, such as the liver and the heart, problems with motion must be addressed. Multi-baseline subtraction techniques have been proposed, which use a library of baseline images covering the respiratory and cardiac cycle. However, main field shifts due to lung and diaphragm motion can cause large inaccuracies in multi-baseline subtraction. Referenceless thermometry methods based on polynomial phase regression are immune to motion and susceptibility shifts. While referenceless methods can accurately estimate temperature within the organ, in general, the background phase at organ/ tissue interfaces requires large polynomial orders to fit, leading to increased danger that the heated region itself will be fitted by the polynomial and thermal dose will be underestimated. In this paper, a hybrid method for PRF thermometry in moving organs is presented that combines the strengths of referenceless and multi-baseline thermometry. Methods: The hybrid image model assumes that three sources contribute to image phase during thermal treatment: Background anatomical phase, spatially smooth phase deviations, and focal, heat-induced phase shifts. The new model and temperature estimation algorithm were tested in the heart and liver of normal volunteers, in a moving phantom HIFU heating experiment, and in numerical simulations of thermal ablation. The results were compared to multi-baseline and referenceless methods alone. Results: The hybrid method allows for in vivo temperature estimation in the liver and the heart with lower temperature uncertainty compared to multi-baseline and referenceless methods. The moving phantom HIFU experiment showed that the method accurately estimates temperature during motion in the presence of smooth main field shifts. Numerical simulations illustrated the method's sensitivity to algorithm parameters and hot spot features. Conclusions: This new hybrid method for MR thermometry in moving organs combines the strengths of both multi-baseline subtraction and referenceless thermometry and overcomes their fundamental weaknesses.

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“…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 patients were treated and the energy application was directly followed by temperature mapping, instead of continuously measuring the temperature during the ablation.…”

Section: Discussionmentioning

confidence: 99%

“…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)(3)(4)(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)(12)(13)(14), which is based on a temperature-dependent phase shift allowing for the measurement of temperature changes relative to a baseline image.…”

mentioning

confidence: 99%

“…Different MR techniques have been proposed for temperature measurement (6 -10); the most frequently used is the proton resonance frequency shift (PRF) method (11)(12)(13)(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.…”

mentioning

confidence: 99%

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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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Real‐time monitoring of radiofrequency ablation of rabbit liver by respiratory‐gated quantitative temperature MRI

Cited by 58 publications

References 24 publications

MR thermometry

MR thermometry

Hybrid referenceless and multibaseline subtraction MR thermometry for monitoring thermal therapies in moving organs

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

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