Characterisation of Ex Vivo Liver Thermal Properties for Electromagnetic-Based Hyperthermic Therapies

Silva, Nuno P.; Bottiglieri, Anna; Conceição, Raquel C.; O’Halloran, Martin; Farina, Laura

doi:10.3390/s20103004

Cited by 33 publications

(51 citation statements)

References 33 publications

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“…Many scientific studies have been presented to measure the thermal properties of biological tissues. These studies are mainly focused on liver tissue [ 18 , 19 , 20 , 21 ] and muscles [ 22 , 23 , 24 , 25 ], and some data are reported for other organs, such as the kidney [ 26 ] and brain [ 27 ]. However, as mentioned before, most of these studies measured the thermal properties at a constant or low temperature which is not completely appropriate for thermal ablation modeling.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Ex Vivo Liver, Brain and Pancreas Thermal Properties as Function of Temperature

Mohammadi

Bianchi

Asadi

et al. 2021

Sensors

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The ability to predict heat transfer during hyperthermal and ablative techniques for cancer treatment relies on understanding the thermal properties of biological tissue. In this work, the thermal properties of ex vivo liver, pancreas and brain tissues are reported as a function of temperature. The thermal diffusivity, thermal conductivity and volumetric heat capacity of these tissues were measured in the temperature range from 22 to around 97 °C. Concerning the pancreas, a phase change occurred around 45 °C; therefore, its thermal properties were investigated only until this temperature. Results indicate that the thermal properties of the liver and brain have a non-linear relationship with temperature in the investigated range. In these tissues, the thermal properties were almost constant until 60 to 70 °C and then gradually changed until 92 °C. In particular, the thermal conductivity increased by 100% for the brain and 60% for the liver up to 92 °C, while thermal diffusivity increased by 90% and 40%, respectively. However, the heat capacity did not significantly change in this temperature range. The thermal conductivity and thermal diffusivity were dramatically increased from 92 to 97 °C, which seems to be due to water vaporization and state transition in the tissues. Moreover, the measurement uncertainty, determined at each temperature, increased after 92 °C. In the temperature range of 22 to 45 °C, the thermal properties of pancreatic tissue did not change significantly, in accordance with the results for the brain and liver. For the three tissues, the best fit curves are provided with regression analysis based on measured data to predict the tissue thermal behavior. These curves describe the temperature dependency of tissue thermal properties in a temperature range relevant for hyperthermia and ablation treatments and may help in constructing more accurate models of bioheat transfer for optimization and pre-planning of thermal procedures.

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Section: Introductionmentioning

confidence: 99%

Measurement of Ex Vivo Liver, Brain and Pancreas Thermal Properties as Function of Temperature

Mohammadi

Bianchi

Asadi

et al. 2021

Sensors

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“…The measurements conducted on the phantoms over time (10 days) are illustrated in Figure 2 and Figure 3 . In the figures, the average value measured each day is reported together with its associated uncertainty, calculated as in [ 16 ], i.e., accounting for the data variability and the device accuracy (10%). In Figure 2 , the thermal conductivity of the three phantoms is shown.…”

Section: Resultsmentioning

confidence: 99%

“…Heat is applied for 30 s to one of the needles of the sensor (heating needle), while the other needle (monitoring needle) records the changes in temperature due to heat transfer from the heating needle to the material under test. The TEMPOS device uses an algorithm to determine the thermal conductivity and thermal diffusivity of the material under test by a least square procedure; then, volumetric heat capacity is derived [16]. The dual-needle sensor is not suitable for measurements in liquid materials due to the convective phenomena induced by the measuring process in between the two needles, which alter the accuracy of the results.…”

Section: Thermal Measurements Set Up and Protocolsmentioning

confidence: 99%

“…In past years, different authors have successfully proposed the use of the transient hot-wire technique reporting consistent results. In [14][15][16], the commercial analyser from METER Group, Inc. USA (Pullman, WA, USA), implementing the same transient hot-wire technique, was used to assess the thermal properties of ex vivo liver tissue as a function of the temperature increase up to ablative temperatures. In [17], the same methodology has been used to assess the changes in thermal properties of ex vivo kidney tissue at ablative temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…One important and well-known limitation of this commercial device is the dimensions of the sensor and thus the dimensions required for the biological sample to accurately perform the measurements. In the system’s manual, it is recommended to “allow a minimum of 15 mm of material parallel to the sensor in all directions to avoid errors.” For the sensor to be able to measure thermal conductivity, volumetric heat capacity and thermal diffusivity (the dual needle-sensor [ 16 ]), the minimum dimensions required for the sample under test (about 25–40 cm 3 ) need to be bigger than the available biological sample. Some biological samples of interest of the electromagnetic hyperthermia community, such as small glands or tissue obtained from pathology, can be substantially smaller than the recommended dimensions.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Characterization of Phantoms Used for Quality Assurance of Deep Hyperthermia Systems

Farina

Sümser

Rhoon

et al. 2020

Sensors

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Tissue mimicking phantoms are frequently used in hyperthermia applications for device and protocol optimization. Unfortunately, a commonly experienced limitation is that their precise thermal properties are not available. Therefore, in this study, the thermal properties of three currently used QA phantoms for deep hyperthermia are measured with an ‘’off-shelf’’ commercial thermal property analyzer. We have measured averaged values of thermal conductivity (k = 0.59 ± 0.07 Wm−1K−1), volumetric heat capacity (C = 3.85 ± 0.45 MJm−3K−1) and thermal diffusivity (D = 0.16 ± 0.02 mm2s−1). These values are comparable with reported values of internal organs, such as liver, kidney and muscle. In addition, a sensitivity study of the performance of the commercial sensor is conducted. To ensure correct thermal measurements, the sample under test should entirely cover the length of the sensor, and a minimum of 4 mm of material parallel to the sensor in all directions should be guaranteed.

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Thermo‐optic measurements and their inter‐dependencies for delineating cancerous breast biopsy tissue from adjacent normal

Pal

Varma

et al. 2021

Journal of Biophotonics

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The histopathological diagnosis of cancer is the current gold standard to differentiate normal from cancerous tissues. We propose a portable platform prototype to characterize the tissue's thermal and optical properties, and their inter‐dependencies to potentially aid the pathologist in making an informed decision. The measurements were performed on 10 samples from five subjects, where the cancerous and adjacent normal were extracted from the same patient. It was observed that thermal conductivity (k) and reduced‐scattering‐coefficient (μ's) for both the cancerous and normal tissues reduced with the rise in tissue temperature. Comparing cancerous and adjacent normal tissue, the difference in k and μ's (at 940 nm) were statistically significant (p = 7.94e‐3), while combining k and μ's achieved the highest statistical significance (6.74e‐4). These preliminary results promise and support testing on a large number of samples for rapidly differentiating cancerous from adjacent normal tissues.

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Characterisation of Ex Vivo Liver Thermal Properties for Electromagnetic-Based Hyperthermic Therapies

Cited by 33 publications

References 33 publications

Measurement of Ex Vivo Liver, Brain and Pancreas Thermal Properties as Function of Temperature

Measurement of Ex Vivo Liver, Brain and Pancreas Thermal Properties as Function of Temperature

Thermal Characterization of Phantoms Used for Quality Assurance of Deep Hyperthermia Systems

Thermo‐optic measurements and their inter‐dependencies for delineating cancerous breast biopsy tissue from adjacent normal

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