<i>T</i><sub>1</sub> relaxation time at 0.2 Tesla for monitoring regional hyperthermia: Feasibility study in muscle and adipose tissue

Peller, Michael; Reinl, Herbert M.; Weigel, Andreas; Meininger, Martin; Issels, Rolf D.; Reiser, Maximilian

doi:10.1002/mrm.10155

Cited by 40 publications

(44 citation statements)

References 36 publications

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“…Studies with a few patients have been performed at Duke University (Durham, NC) 20 and at Klinikum Grosshadern (Munich, Germany). 21 Regarding the role of RHT as an adjunct to radiotherapy and/or chemotherapy in the treatment of locally advanced STS, a sound rationale has been established in a number of Phase II trials. 5,22,23 In addition, the oncologic impact of hyperthermia in the treatment of these tumors currently is being evaluated in an ongoing randomized trial of the EORTC/European Society for Hyperthermic Oncology (ESHO).…”

Section: Resultsmentioning

confidence: 99%

Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

Gellermann

Hildebrandt

Issels³

et al. 2006

Cancer

128

101

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BACKGROUND The objective of this study was to evaluate noninvasive magnetic resonance (MR) thermography for the monitoring of regional hyperthermia (RHT) in patients with soft tissue sarcomas of the lower extremities and pelvis. METHODS Noninvasive MR monitoring during RHT was performed in 9 patients who had high‐risk soft tissue sarcomas of the lower extremities or pelvis during neoadjuvant chemotherapy plus RHT in the scope of the European Organization for Research and Treatment of Cancer 62961/European Society for Hyperthermic Oncology RHT‐95 study. Anatomic and temperature‐sensitive data sets were acquired every 10 minutes before and during RHT (using gradient‐echo‐sequences with variable echo times). MR temperature distributions were derived from the phase differences by using the proton‐resonance frequency shift method. A phase convolution setting phase shifts to zero in the fat tissue was performed as a drift correction. The mean MR temperatures in the tumor and muscles and the index temperatures (e.g., T90, which covers 90% of the target volume) and thermal doses were determined and compared with pathohistologic responses and direct temperature measurements if available. RESULTS Thirty of 72 MR‐thermography data sets (>40% of heat sessions) were evaluable. A significant correlation was observed between pathohistologic response (defined as a necrosis rate ≥90%) and standardized thermal parameters, such as thermal dose cumulative equivalent minutes at 43°C to 90% of the target volume (T90) (P = .050), mean T90 (P = .048), or T50 (P = .050). The correlation of 13 conventional temperature measurements performed in selected patients and sessions invasively in the tumor or noninvasively in rectum and bladder revealed an excellent correlation with MR temperatures (R2 = .96). CONCLUSIONS Noninvasive MR thermography of soft tissue sarcoma was feasible and suitable for validating the quality of heating during RHT. Cancer 2006. © 2006 American Cancer Society.

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Section: Resultsmentioning

confidence: 99%

Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

Gellermann

Hildebrandt

Issels³

et al. 2006

Cancer

128

101

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“…Many accurate T 1 mapping methods such as inversion recovery and saturation recovery are very time-consuming and not useful for monitoring thermal therapy, although single-shot methods partially alleviate the problem. A fast T 1 mapping method, T 1 by multiple read-out pulses (TOMROP), allows acquisition of multiple slices in about 4 minutes, which might be an acceptable time frame for hyperthermia (29). Lipid suppression should be used because the presence of lipids, which have a different T 1 change with temperature, is a potential source of artifacts.…”

Section: T 1 Relaxation Time Of Water Protonsmentioning

confidence: 99%

“…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). Because of these problems, T 1 changes are often only used to get a qualitative measure of the temperature distribution.…”

Section: T 1 Relaxation Time Of Water Protonsmentioning

confidence: 99%

MR thermometry

Rieke

Pauly

2008

Magnetic Resonance Imaging

1,023

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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“…The composition of polyacrylamide-based materials, in particular, can be adjusted to mimic the electrical and thermal properties of various types of human tissue [1][2][3] . As a result, these materials have been used extensively to evaluate radiofrequency (RF) and microwave applicators for hyperthermia and thermal therapy [4][5][6][7][8][9][10][11][12][13][14][15][16] , to validate numerical simulations of RF and microwave-based hyperthermia treatments 13,[17][18][19] and to evaluate the use of various thermometry techniques in RF and microwave hyperthermia [20][21][22][23][24][25][26] .…”

Section: Introductionmentioning

confidence: 99%

Measurement of the thermal conductivity of polyacrylamide tissue-equivalent material

Davidson

Sherar

2003

International Journal of Hyperthermia

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The purpose of this work was to measure the thermal conductivity of polyacrylamide (PAG) and compare it with previously reported values. Polyacrylamide phantoms play an important role in the development of hyperthermia and high-temperature thermal therapies based on electromagnetic (EM) radiation by providing a material that mimics the electrical and thermal properties of human tissue. The thermal properties of PAG have, up until now, not been thoroughly investigated and at least two significantly different values have been published. In this study, the thermal conductivity of polyacrylamide was measured from the steady state temperature drop across samples exposed to a known heat flux. The measured conductivity was 0.56 +/- 0.047 W m(-1) degrees C(-1). To validate the correct set of thermal properties for polyacrylamide, simple heating experiments were performed in a PAG phantom and then simulated using a finite element numerical model that incorporated the measured thermal conductivity along with literature values for specific heat and density. Temperature predictions from the model agreed with average temperatures measured in the phantom to within 1 SD of the measured temperatures.

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T₁ relaxation time at 0.2 Tesla for monitoring regional hyperthermia: Feasibility study in muscle and adipose tissue

Abstract: The purpose of this study was to characterize T 1 , particularly in the hyperthermia temperature range (ca. 37-44°C), in order to control regional hyperthermia with MR monitoring using 0.

Cited by 40 publications

References 36 publications

Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

MR thermometry

Measurement of the thermal conductivity of polyacrylamide tissue-equivalent material

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T1 relaxation time at 0.2 Tesla for monitoring regional hyperthermia: Feasibility study in muscle and adipose tissue

Abstract: The purpose of this study was to characterize T 1 , particularly in the hyperthermia temperature range (ca. 37-44°C), in order to control regional hyperthermia with MR monitoring using 0.

Cited by 40 publications

References 36 publications

Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

Noninvasive magnetic resonance thermography of soft tissue sarcomas during regional hyperthermia

MR thermometry

Measurement of the thermal conductivity of polyacrylamide tissue-equivalent material

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Product

Resources

About

T₁ relaxation time at 0.2 Tesla for monitoring regional hyperthermia: Feasibility study in muscle and adipose tissue