Influence of water and fat heterogeneity on fat‐referenced MR thermometry

Baron, Paul; Deckers, Roel; Bouwman, Job G.; Bakker, Chris J.G.; Greef, Martijn de; Viergever, Max A.; Moonen, Chrit; Bartels, Lambertus W.

doi:10.1002/mrm.25727

Cited by 24 publications

(45 citation statements)

References 45 publications

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“…Methylene protons, on the contrary, are not a good reference for water protons, as they reside in different compartments and experience different field perturbations. Consequently, variations in the water/fat spatial distribution are expected to lead to variations in the observed water-fat frequency difference (23) and, unless the exact distribution of water and fat spins is known at the sub-voxel level, PRF-based thermometry methods are expected to show an acceptable performance only at moderate temperature elevations and/or in voxels with low fat contents.…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, the local magnetic field perturbation due to magnetic susceptibility mismatch between water and fat compartments was first computed in MATLAB (MathWorks, Natick, MA), similarly to what was recently done by Baron et al (23). This was accomplished by using a Fourier based method first introduced by Deville et al (34) and by Salomir et al (35).…”

Section: Methodsmentioning

confidence: 99%

“…In fatty tissues, inadvertent motion and phase-unwrapping errors caused by susceptibility gradients generated by water/fat interfaces can render temperature readings less accurate. The effect of such susceptibility gradients on the accuracy of MR thermometry was already analyzed previously by De Poorter et al (22) and, more recently, by Baron et al (23), who proposed a model-based correction method to estimate the proton resonance frequency shift caused by temperature-induced magnetic susceptibility changes in the presence of fat (24). Another way to improve the accuracy of PRF shift (PRFS) based MR thermometry is to use a ‘temperature independent’ resonance frequency, usually that of the methylene protons of nearby lipid molecules, as an internal reference to correct for field variations (25,26) or even to extract absolute temperature information (27).…”

Section: Introductionmentioning

confidence: 98%

“…Another way to improve the accuracy of PRF shift (PRFS) based MR thermometry is to use a ‘temperature independent’ resonance frequency, usually that of the methylene protons of nearby lipid molecules, as an internal reference to correct for field variations (25,26) or even to extract absolute temperature information (27). Unfortunately, since water and lipid spins always reside in different tissue or cell compartments, the effect of local susceptibility gradients cannot be completely removed, as also pointed out by Baron et al (23). To make matters worse, even though the resonance frequency of lipid spins remains virtually temperature independent over a wide range with a coefficient measured to be around +0.00018 ppm/°C (28), the magnetic susceptibility of fat has a relatively strong temperature dependence of 0.01 ppm/°C (22,29), which can lead to significant temperature-induced changes in the local magnetic field distribution, reducing the accuracy of PRF-based relative temperature measurements in the presence of fat.…”

Section: Introductionmentioning

confidence: 99%

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Accurate MR thermometry by hyperpolarized ¹²⁹Xe

Zhang

Burant

McCallister

et al. 2016

Magnetic Resonance in Med

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Purpose To investigate the temperature dependence of the resonance frequency of Lipid-Dissolved Xenon (LDX) and to assess the accuracy of LDX-based MR thermometry. Methods The chemical shift temperature dependence of water protons, methylene protons, and LDX was measured from samples containing tissues with varying fat contents using a high-resolution NMR spectrometer. LDX results were then used to acquire relative and absolute temperature maps in vivo and the results were compared to PRF-based MR thermometry. Results The temperature dependence of PRF is strongly affected by the specific distribution of water and fat. A redistribution of water and fat compartments can reduce the apparent temperature dependence of the water chemical shift from −0.01ppm/°C to −0.006ppm, whereas the LDX chemical shift shows a consistent temperature dependence of −0.21ppm/°C. The use of the methylene protons resonance frequency as internal reference improves the accuracy of LDX-based MR thermometry but degrades that of PRF-based MR thermometry as microscopic susceptibility gradients affected lipid and water spins differently. Conclusion The LDX resonance frequency, with its higher temperature dependence, provides more accurate and precise temperature measurements, both in vitro and in vivo. More importantly, the resonance frequency of nearby methylene protons can be used to extract absolute temperature information.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Accurate MR thermometry by hyperpolarized ¹²⁹Xe

Zhang

Burant

McCallister

et al. 2016

Magnetic Resonance in Med

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“…This is a major drawback of the PRF method for accurate MR thermometry in and around fatty tissues (43,62). While the temperature dependent magnetic susceptibility of water based tissue is rather small with ݀߯ ௪௧ /݀ܶ = 0.0016 ‫ܥ°/݉‬ (muscle tissue (42)) as compared to the changes in the electron screening constant, the susceptibility of fat ݀߯ ௧ /݀ܶ = 0.0039 − 0.0076 ‫ܥ°/݉‬ (breast fat (43)) is close to the proton electron screening of water (43) ( Table I).…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Magnetic resonance thermometry: Methodology, pitfalls and practical solutions

Winter

Oberacker

Paul

et al. 2015

International Journal of Hyperthermia

176

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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