Modeling and observation of temperature changes <i>in Vivo</i> using MRI

Young, I. R.; Hand, J.W.; Oatridge, Angela; Prior, M.V.

doi:10.1002/mrm.1910320311

Cited by 103 publications

(70 citation statements)

References 32 publications

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“…The proton resonant frequency technique appears to be the most suitable method for online thermometry [12,13,19,[32][33][34], since it is nearly independent of tissue characteristics, is linear with temperature increase and is compatible with fast imaging sequences. In the present study, the feasibility of quantitative MR thermometry monitoring simultaneously with radiofrequency ablation on pig liver in vivo was demonstrated using standard clinical MR and radiofrequency instrumentation.…”

Section: Discussionmentioning

confidence: 99%

Real time monitoring of radiofrequency ablation based on MR thermometry and thermal dose in the pig liver in vivo

et al. 2007

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Real time monitoring of radiofrequency ablation based on MR thermometry and thermal dose in the pig liver in vivo Abstract To evaluate the feasibility and accuracy of MR thermometry based on the thermal dose (TD) concept for monitoring radiofrequency (RF) ablations, 13 RF ablations in pig livers were performed under continuous MR thermometry at 1.5 T with a filtered clinical RF device. Respiratory gated fast gradient echo images were acquired simultaneously to RF deposition for providing MR temperature maps with the proton resonant frequency technique. Residual motion, signal to noise ratio (SNR) and standard deviation (SD) of MR temperature images were quantitatively analyzed to detect and reject artifacted images in the time series. SD of temperature measurement remained under 2°C. Macroscopic analysis of liver ablations showed a white zone (Wz) surrounded by a red zone (Rz). A detailed histological analysis confirmed the ongoing nature of the coagulation necrosis in both Wz and Rz. Average differences (±SD) between macroscopic size measurements of Wz and Rz and TD predictions of ablation zones were 4.1 (±1.93) mm and −0.71 (±2.47) mm, respectively. Correlation values between TD and Wz and TD and Rz were 0.97 and 0.99, respectively. MR thermometry monitoring based on TD is an accurate method to delineate the size of the ablation zone during the RF procedure and provides a clinical endpoint.

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Section: Discussionmentioning

confidence: 99%

Real time monitoring of radiofrequency ablation based on MR thermometry and thermal dose in the pig liver in vivo

et al. 2007

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“…The quantification of temperature changes using T 1 effects is difficult because the temperature coefficient of the individual tissues is usually not known and the physiologic response of the living tissue to heat can seriously affect the quantification (30). Nonlinear effects can also occur if the tissue properties change, eg, due to coagulation, which has been found in ex vivo tissue to occur at temperatures as low as 43°C (29).…”

Section: T 1 Relaxation Time Of Water Protonsmentioning

confidence: 99%

“…This results in a decrease in the MR visible signal in areas of macromolecules affected by magnetization transfer. Because these MT exchange processes are temperature-dependent, they can potentially be used for temperature measurements (30,40). However, the sensitivity of this method is limited and strongly tissue-dependent.…”

Section: Magnetization Transfermentioning

confidence: 99%

MR thermometry

Rieke

Pauly

2008

Magnetic Resonance Imaging

1,007

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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“…[21][22][23]. As T1-weighted sequences are particularly dependent on the type and status of the tissue (24,25), they are mainly recommended in low-field systems because of their higher contrast. On the contrary, diffusion methods still suffer from technical and methodical limitations in clinical practice (26).…”

Section: Introductionmentioning

confidence: 99%

Noninvasive Magnetic Resonance Thermography of Recurrent Rectal Carcinoma in a 1.5 Tesla Hybrid System

Gellermann¹,

Wlodarczyk²,

Hildebrandt³

et al. 2005

Cancer Research

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To implement noninvasive thermometry, we installed a hybrid system consisting of a radiofrequency multiantenna applicator (SIGMA-Eye) for deep hyperthermia (BSD-2000/3D) integrated into the gantry of a 1.5 Tesla magnetic resonance (MR) tomograph Symphony. This system can record MR data during radiofrequency heating and is suitable for application and evaluation of methods for MR thermography. In 15 patients with preirradiated pelvic rectal recurrences, we acquired phase data sets (25 slices) every 10 to 15 minutes over the treatment time (60-90 minutes) using gradient echo sequences (echo time = 20 ms), transformed the phase differences to MR temperatures, and fused the color-coded MR-temperature distributions with anatomic T1-weighted MR data sets. We could generate one complete series of MR data sets per patient with satisfactory quality for further analysis. In fat, muscle, water bolus, prostate, bladder, and tumor, we delineated regions of interest (ROI), used the fat ROI for drift correction by transforming these regions to a phase shift zero, and evaluated the MR-temperature frequency distributions. Mean MR temperatures (T MR ), maximum T MR , full width half maximum (FWHM), and other descriptors of tumors and normal tissues were noninvasively derived and their dependencies outlined. In 8 of 15 patients, direct temperature measurements in reference points were available. We correlated the tumor MR temperatures with direct measurements, clinical response, and tumor features (volume and location), and found reasonable trends and correlations. Therefore, the mean T MR of the tumor might be useful as a variable to evaluate the quality and effectivity of heat treatments, and consequently as optimization variable. Feasibility of noninvasive MR thermography for regional hyperthermia has been shown and should be further investigated. (Cancer Res 2005; 65(13): 5872-80)

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Modeling and observation of temperature changes in Vivo using MRI

Cited by 103 publications

References 32 publications

Real time monitoring of radiofrequency ablation based on MR thermometry and thermal dose in the pig liver in vivo

Real time monitoring of radiofrequency ablation based on MR thermometry and thermal dose in the pig liver in vivo

MR thermometry

Noninvasive Magnetic Resonance Thermography of Recurrent Rectal Carcinoma in a 1.5 Tesla Hybrid System

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