Impact of cysts during radiofrequency lesioning in deep brain structures—a simulation and<i>in vitro</i>study

Johansson, Johannes; Loyd, Dan; Wårdell, Karin; Wren, Joakim

doi:10.1088/1741-2560/4/2/009

Cited by 7 publications

(4 citation statements)

References 25 publications

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“…13 Electrical properties are also necessary in estimating the specific absorption rate of cell phone radiation to the human brain or the absorption of any other electromagnetic radiation, such as short-range energy transfer, in calculating fields in transcranial magnetic stimulation (TMS) 23 or in transcranial direct-current stimulation (tDCS). 16 Further, the values are beneficial in planning the treatment of tumours with radiofrequency-induced hyperthermia 15 or planning transcranial direct-current stimulation treatment. 6 Several researchers have expressed the need for accurate tissue and tumour values.…”

Section: Introductionmentioning

confidence: 99%

The Resistivity of Human Brain Tumours In Vivo

Latikka

Eskola

2019

Ann Biomed Eng

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The histological structure of tumour tissues differs from healthy brain tissues. It can therefore be assumed that there are differences also in the electrical characteristics of these tissues. The electrical characteristics of the tissues define how electric current is distributed within volume conductors, such as the human body or head. Incorrect values affect, for example, the accuracy of impedance tomography or EEG source localisation. However, no controlled experimental data for human in vivo brain tumour resistivity values have been reported thus far. We have developed a controlled method for detecting the electrical resistivities of living brain tissue and investigated different types of brain tumours. The measurements were taken during brain surgeries conducted to remove the tumours. For analysis purposes, the tumours were divided into the following categories: meningiomas, low-grade gliomas, high-grade gliomas (glioblastomas) and other tumours or lesions. The averages of the measured resistivity values were 530 X-cm for meningiomas, 160 X-cm for low-grade gliomas, and 498 Xcm for high-grade gliomas. The differences in high-and lowgrade glioma values and meningioma and low-grade glioma values were statistically highly significant. The tumour values were also compared to surrounding healthy brain tissues, and the difference ranged from 40 to 330%. The results suggest that certain tumour types have different electronic properties and that the resistivity values could be used to distinguish tumour tissue from surrounding healthy tissue and to identify and classify certain brain tumour types.

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Section: Introductionmentioning

confidence: 99%

The Resistivity of Human Brain Tumours In Vivo

Latikka

Eskola

2019

Ann Biomed Eng

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“…CSF is of particular interest to us as simulation studies indicate that its presence can affect both DBS [9] and RF lesioning [8]. The results from this study predict that a sufficient large amount of CSF ahead of the electrode should give a considerable decrease in I 780 (Figure 5a).…”

Section: Discussionmentioning

confidence: 81%

“…From previous studies we have reason to believe that cerebrospinal fluid (CSF) in e.g. cysts can have an important impact on RF lesioning [8] and deep brain stimulation [9] and we are thus interested in methods for detecting them.…”

Section: Introductionmentioning

confidence: 99%

Simulation of reflected light intensity changes during navigation and radio-frequency lesioning in the brain

Johansson

Fredriksson²,

Wårdell

et al. 2009

J. Biomed. Opt.

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An electrode with adjacent optical fibers for measurements during navigation and radio frequency lesioning in the brain was modeled for Monte Carlo simulations of light transport in brain tissue. Relative reflected light intensity at 780 nm, I 780 , from this electrode and probes with identical fiber configuration were simulated using the intensity from native white matter as reference. Models were made of homogeneous native and coagulated gray, thalamus, and white matter as well as blood. Dual layer models, including models with a layer of cerebrospinal fluid between the fibers and the brain tissue, were also made. Simulated I 780 was 0.16 for gray matter, 0.67 for coagulate gray matter, 0.36 for thalamus, 0.39 for coagulated thalamus, unity for white matter, 0.70 for coagulated white matter and 0.24 for blood. Thalamic matter has also been found to reflect more light than gray matter and less than white matter in clinical studies. In conclusion the reflected light intensity can be used to differentiate between gray and white matter during navigation. Furthermore, coagulation of light gray tissue, such as the thalamus, might be difficult to detect 2 using I 780 , but coagulation in darker gray tissue should result in a rapid increase of I 780 .

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“…pallidum) and the proximity of the lamina medullaris interna to, or even its inclusion in, the lesion area in the posteroventral part of that nucleus. The presence of Virshow-Robin spaces, although not uncommon in the posteroventral putamen but rare in the pallidal target area, is likely to have some impact on the lesion volume, and on heat losses by diffusion, convection via circulation and low resistance shunting, all of which will contribute further to the difficulty to predict the lesion size [23,35]. Biological factors might also have influenced the lesion volume.…”

Section: Discussionmentioning

confidence: 99%

Impact of Parameters of Radiofrequency Coagulation on Volume of Stereotactic Lesion in Pallidotomy and Thalamotomy

Hirabayashi

Hariz²,

Wårdell

et al. 2012

Stereotact Funct Neurosurg

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Background: One of the many reasons why lesional surgery for movement disorders has been more or less abandoned may have been the difficulty in predicting the shape and size of the stereotactic radiofrequency (RF) lesion. Objectives: To analyse the contribution of various RF coagulation parameters towards the volume of pallidotomies and thalamotomies. Methods: The relationship between temperature of coagulation, length of coagulated area and duration of coagulation on the one hand, and lesion volume on the other was retrospectively evaluated. Lesion diameters were measured on stereotactic thin-slice CT and MRI scans, and volumes of lesions were calculated concerning 36 pallidotomies and 14 thalamotomies in 46 patients who were operated using the same RF generator and same RF electrode. Results: The coagulation temperature, length of coagulated area and duration of coagulation were all correlated to the lesion volume. However, for a given length of coagulated area, the lesion´s size was most strongly influenced by the temperature. Despite this clear correlation, and the relatively homogenous coagulation parameters, the lesions’ volumes were markedly scattered. Conclusions: The volume of the stereotactic RF lesions could be correlated with the coagulation parameters, especially the temperature, at a group level, but could not be predicted in individual patients based solely on the RF coagulation parameters.

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Impact of cysts during radiofrequency lesioning in deep brain structures—a simulation andin vitrostudy

Cited by 7 publications

References 25 publications

The Resistivity of Human Brain Tumours In Vivo

The Resistivity of Human Brain Tumours In Vivo

Simulation of reflected light intensity changes during navigation and radio-frequency lesioning in the brain

Impact of Parameters of Radiofrequency Coagulation on Volume of Stereotactic Lesion in Pallidotomy and Thalamotomy

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