Referenceless MR Thermometry for Monitoring Thermal Ablation in the Prostate

Rieke, Viola; Kinsey, Adam M.; Ross, Anthony B.; Nau, William H.; Diederich, Chris J.; Sommer, Graham; Pauly, Kim Butts

doi:10.1109/tmi.2007.892647

Cited by 70 publications

(55 citation statements)

References 29 publications

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“…For an immobilized breast, a spatially averaged respirationinduced B 0 variation of 0.14 parts per million (ppm) has been reported (19). This corresponds to a PRFS measurement fluctuation of approximately 14 C. While the prostate is less prone to respiratory motion effects, bowel movement and involuntary muscle contractions can cause similar motion-induced measurement errors due to temporal field perturbations (20). In these challenging anatomies, methods for correcting measurement inaccuracies due to phase disturbances are critical.…”

Section: Conclusion: Ex Vivo and In Vivo Resultsmentioning

confidence: 99%

“…The reference less method (20)(21)(22) uses phase information outside of the heated area to estimate background phase in the heated zone, thus allowing both the background phase information and temperature induced phase change to be obtained from a single image. Deriving the temperature map from a single image can significantly reduce errors caused by motion and time-varying field perturbations.…”

Section: Conclusion: Ex Vivo and In Vivo Resultsmentioning

confidence: 99%

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Fat‐referenced MR thermometry in the breast and prostate using IDEAL

Hofstetter

Dixon

Kempf

et al. 2012

Magnetic Resonance Imaging

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Purpose: To demonstrate a three-echo fat-referenced MR thermometry technique that estimates and corrects for time-varying phase disturbances in heterogeneous tissues. Materials and Methods:Fat protons do not exhibit a temperature-dependent frequency shift. Fat-referenced thermometry methods exploit this insensitivity and use the signal from fat to measure and correct for magnetic field disturbances. In this study, we present a fat-referenced method that uses interpolation of the fat signal to correct for phase disturbances in fat free regions. Phantom and ex vivo tissue cool-down experiments were performed to evaluate the accuracy of this method in the absence of motion. Non-heated in vivo imaging of the breast and prostate was performed to demonstrate measurement robustness in the presence of systemic and motioninduced field disturbances. Measurement accuracy of the method was compared to conventional proton resonance frequency shift MR thermometry.Results: In the ex vivo porcine tissue experiment, maximum measurement error of the fat-referenced method was reduced 42% from 3.3 to 1.9C when compared to conventional MR thermometry. In the breasts, measurement errors were reduced by up to 70% from 6.4 to 1.9 C.Conclusion: Ex vivo and in vivo results show that the proposed method reduces measurement errors in the heterogeneous tissue experiments when compared to conventional MR thermometry.

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Section: Conclusion: Ex Vivo and In Vivo Resultsmentioning

confidence: 99%

Section: Conclusion: Ex Vivo and In Vivo Resultsmentioning

confidence: 99%

Fat‐referenced MR thermometry in the breast and prostate using IDEAL

Hofstetter

Dixon

Kempf

et al. 2012

Magnetic Resonance Imaging

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“…This is often the case for thermal ablation procedures but not in hyperthermia. Because of echo time-dependent phase discontinuities between water and fat regions, which would inhibit polynomial fitting, fat needs to be suppressed or the reconstruction algorithm should be modified to be able to handle both tissue types (100). Figure 8 shows temperature maps in a canine prostate without heating, while light pressure was applied to the animal's abdomen, demonstrating the ability of referenceless thermometry to measure temperature in the presence of tissue motion.…”

Section: Prf Thermometry and Motionmentioning

confidence: 99%

MR thermometry

Rieke

Pauly

2008

Magnetic Resonance Imaging

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1,005

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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“…Any intra-scan motion leading to misregistration with the reference phase image results in temperature errors. These errors might be caused by respiratory, cardiac, peristaltic or bulk motion with standard deviations of >±10°C even without any application of heat (25,73). Structural changes of the treatment area due to tissue coagulation during an ablation procedure (40) This library is used to link the phase measured during thermal therapy to the correct reference image by means of an acquired navigator echo (22), non-similarity coefficients (77) or intercorrelation coefficients (78,79).…”

Section: Motionmentioning

confidence: 99%

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

Winter

Oberacker

Paul

et al. 2015

International Journal of Hyperthermia

185

165

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Clinically established thermal therapies like thermo ablative approaches or adjuvant hyperthermia treatment rely on accurate thermal dose information for the evaluation and adaptation of the thermal therapy. Intratumoral temperature measurements have been correlated successfully with clinical endpoints. Magnetic resonance imaging is the most suitable technique for non-invasive thermometry avoiding complications related to invasive temperature measurements. Since the advent of MR thermometry two decades ago, numerous MR thermometry techniques have been developed continuously increasing accuracy and robustness for in vivo applications. While this progress was primarily focused on relative temperature mapping, current and future efforts will likely close the gap towards quantitative temperature readings. These efforts are essential to benchmark thermal therapy efficiency, understand temperature related biophysical and physiological processes and to use these insights to set new landmarks for diagnostic and therapeutic applications. With that in mind, this review summarizes and discusses advances in MR thermometry providing practical considerations, pitfalls and technical obstacles constraining temperature measurement accuracy, spatial and temporal resolution in vivo. Established approaches and current trends in thermal therapy hardware are surveyed with respect to potential benefits for MR thermometry.3

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Referenceless MR Thermometry for Monitoring Thermal Ablation in the Prostate

Cited by 70 publications

References 29 publications

Fat‐referenced MR thermometry in the breast and prostate using IDEAL

Fat‐referenced MR thermometry in the breast and prostate using IDEAL

MR thermometry

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

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