Variability of Size and Shape of Necrosis Induced by Radiofrequency Ablation in Human Livers: A Volumetric Evaluation

Stippel, Dirk L.; Brochhagen, Hans-Georg; Arenja, Mahesh; Hunkemöller, Jens; Hölscher, A. H.; Beckurts, K. T. E.

doi:10.1245/aso.2004.09.012

Cited by 56 publications

(43 citation statements)

References 14 publications

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“…Since most lumps or tumors are roughly spherical or ellipsoid in shape [40], detection of surface curvature is important for observing the presence of a lump and estimating its size. Goodwin et al stimulated the human finger pad with rigid spherical stimuli of varying radii, and showed that slight changes in curvature (especially for stimuli smaller than a single finger pad) can drastically effect the firing rate of SA I mechanoreceptors [12,14] and the perception [13] of the stimulus curvature.…”

Section: Softness Discriminationmentioning

confidence: 99%

Human vs. robotic tactile sensing: Detecting lumps in soft tissue

Gwilliam

Pezzementi

Jantho

et al. 2010

2010 IEEE Haptics Symposium

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Humans can localize lumps in soft tissue using the distributed tactile feedback and processing afforded by the fingers and brain. This task becomes extremely difficult when the fingers are not in direct contact with the tissue, such as in laparoscopic or robot-assisted procedures. Tactile sensors have been proposed to characterize and detect lumps in robot-assisted palpation. In this work, we compare the performance of a capacitive tactile sensor with that of the human finger. We evaluate the response of the sensor as it pertains to robot-assisted palpation and compare the sensor performance to that of human subjects performing an equivalent task on the same set of artificial tissue models. Furthermore, we investigate the effects of various tissue parameters (lump size, lump depth, and surrounding tissue stiffness) on the performance of both the human finger and the tactile sensor. Using signal detection theory for determining tactile sensor lump detection thresholds, the tactile sensor outperforms the human finger in a palpation task.

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Section: Softness Discriminationmentioning

confidence: 99%

Human vs. robotic tactile sensing: Detecting lumps in soft tissue

Gwilliam

Pezzementi

Jantho

et al. 2010

2010 IEEE Haptics Symposium

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“…Additionally, alternative treatments such as the use of tumor ablation with radiofrequency devices also have the potential to be quantified using tumor volumetric evaluation. 16 While liver lesions are commonly assessed with contrastenhanced CT, many patients also undergo combined PET/ CT. In PET/CT, the PET information is used to determine the functional status of the tissue, while the CT is used for PET attenuation correction and localization.…”

Section: ͒mentioning

confidence: 99%

Comparison of two‐dimensional and three‐dimensional iterative watershed segmentation methods in hepatic tumor volumetrics

et al. 2008

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In this work the authors compare the accuracy of two-dimensional ͑2D͒ and three-dimensional ͑3D͒ implementations of a computer-aided image segmentation method to that of physician observers ͑using manual outlining͒ for volume measurements of liver tumors visualized with diagnostic contrast-enhanced and PET/CT-based non-contrast-enhanced ͑PET-CT͒ CT scans. The method assessed is a hybridization of the watershed method using observer-set markers with a gradient vector flow approach. This method is known as the iterative watershed segmentation ͑IWS͒ method. Initial assessments are performed using software phantoms that model a range of tumor shapes, noise levels, and noise qualities. IWS is then applied to CT image sets of patients with identified hepatic tumors and compared to the physicians' manual outlines on the same tumors. The repeatability of the physicians' measurements is also assessed. IWS utilizes multiple levels of segmentation performed with the use of "fuzzy regions" that could be considered part of a selected tumor. In phantom studies, the outermost volume outline for level 1 ͑called level 1_1 consisting of inner region plus fuzzy region͒ was generally the most accurate. For in vivo studies, the level 1_1 and the second outermost outline for level 2 ͑called level 2_2 consisting of inner region plus two fuzzy regions͒ typically had the smallest percent error values when compared to physician observer volume estimates. Our data indicate that allowing the operator to choose the "best result" level iteration outline from all generated outlines would likely give the more accurate volume for a given tumor rather than automatically choosing a particular level iteration outline. The preliminary in vivo results indicate that 2D-IWS is likely to be more accurate than 3D-IWS in relation to the observer volume estimates.

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“…With current electrodes, large ablation zones can be obtained but their predictability and completeness is problematic. Size and shape of the ablation zone are highly variable and difficult to predict [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] even in the most standardised ex vivo experiments (Table 1). A standard deviation of the ablation diameter, especially the transverse diameter, of 0.5-1 cm is very common (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Bipolar radiofrequency ablation with 2 × 2 electrodes as a building block for matrix radiofrequency ablation:Ex vivoliver experiments and finite element method modelling

Mulier

Jiang

Jamart

et al. 2015

International Journal of Hyperthermia

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Purpose: Size and geometry of the ablation zone obtained by currently available radiofrequency (RF) electrodes is highly variable. Reliability might be improved by matrix radiofrequency ablation (MRFA), in which the whole tumour volume is contained within a cage of x Â y parallel electrodes. The aim of this study was to optimise the smallest building block for matrix radiofrequency ablation: a recently developed bipolar 2 Â 2 electrode system. Materials and methods: In ex vivo bovine liver, the parameters of the experimental set-up were changed one by one. In a second step, a finite element method (FEM) modelling of the experiment was performed to better understand the experimental findings. Results:The optimal power to obtain complete ablation in the shortest time was 50-60 W. Performing an ablation until impedance rise was superior to ablation for a fixed duration. Increasing electrode diameter improved completeness of ablation due to lower temperature along the electrodes. A chessboard pattern of electrode polarity was inferior to a row pattern due to an electric field void in between the electrodes. Variability of ablation size was limited. The FEM correctly simulated and explained the findings in ex vivo liver. Conclusions: These experiments and FEM modelling allowed a better insight in the factors influencing the ablation zone in a bipolar 2 Â 2 electrode RF system. With optimal parameters, complete ablation was obtained quickly and with limited variability. This knowledge will be useful to build a larger system with x Â y electrodes for MRFA.

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Variability of Size and Shape of Necrosis Induced by Radiofrequency Ablation in Human Livers: A Volumetric Evaluation

Cited by 56 publications

References 14 publications

Human vs. robotic tactile sensing: Detecting lumps in soft tissue

Human vs. robotic tactile sensing: Detecting lumps in soft tissue

Comparison of two‐dimensional and three‐dimensional iterative watershed segmentation methods in hepatic tumor volumetrics

Bipolar radiofrequency ablation with 2 × 2 electrodes as a building block for matrix radiofrequency ablation:Ex vivoliver experiments and finite element method modelling

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