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Interactive Volumetry Of Liver Ablation Zones.

Egger J, Busse H, Brandmaier P, Seider D, Gawlitza M, Strocka S, Voglreiter P, Dokter M, Hofmann M, Kainz B, Hann A, Chen X, Alhonnoro T, Pollari M, Schmalstieg D, Moche M - Sci Rep (2015)

Bottom Line: For the quantitative and qualitative analysis of the algorithm's results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other).The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation.The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University, Rakentajanaukio 2 C, 02150 Espoo, Finland.

ABSTRACT
Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm's results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.

No MeSH data available.


Related in: MedlinePlus

Schematic view of the liver (brown) with a fully expanded and umbrella-shaped radiofrequency ablation (RFA) needle (black).The needle tips are located in a liver tumor (red) surrounded by the so called necrotic zone (light brown).
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f1: Schematic view of the liver (brown) with a fully expanded and umbrella-shaped radiofrequency ablation (RFA) needle (black).The needle tips are located in a liver tumor (red) surrounded by the so called necrotic zone (light brown).

Mentions: Liver cancer is on the rise worldwide, mainly because of hepatitis infection and alcohol abuse. Especially patients with primary liver cancer (Hepatocellular Carcinomas, HCC) have a poor prognosis because, of its late symptomatic onset, resulting in a median survival time of four to six months from the time of diagnosis, when untreated. According to the recent treatment guidelines1, radiofrequency ablation (RFA) serves as a first line therapy approach for early HCC in patients with liver cirrhosis. Also, for metastatic liver disease, the local usage of ablation therapies increases. While the technique was originally developed for patients who were not eligible for surgery its use has now expanded to serve as a bridge to liver transplantation and even as an alternative to surgical resection in the early stages of the disease2. RFA was first described in the early 1990s, followed by huge technical advances throughout the last decades. The underlying principle is based on a high frequency alternating current, which is delivered through one or more electrodes in the treated lesion3 (see Fig. 1 for a schematic view of RFA needle placement in a liver tumor, including the surrounding necrotic zone, and Fig. 2 for a postinterventional computed tomography (CT) scan with ablation needle). Optimally, the heat destroys cancer cells by inducing a coagulative necrosis, with cellular proteins being denaturized. Most commonly, tissue necrosis already begins at approximately 60 °C, but usually, temperatures around 100° are needed to achieve satisfying results. The amount of destroyed tissue mostly depends on the individual impedance and placement of the needle. Furthermore, it is inversely proportional to the square of the distance from the electrode. As a result, tissue cools rapidly away from the tip of the needle probe. Hence, the proximity to large blood vessels also plays a major role in the heat transmission. Blood flow protects the vessel wall from damage, but, on the flipside, acts as a heat sink by cooling down nearby tissue limiting the methods overall success4. As a consequence, a significant mismatch between expected and truly induced lesion size and geometry has been observed in many radio-frequency ablations performed in the liver. It can lead to over-treatment with severe injuries (up to 9% major complications5), or under-treatment with tumor recurrence (up to 40%5).


Interactive Volumetry Of Liver Ablation Zones.

Egger J, Busse H, Brandmaier P, Seider D, Gawlitza M, Strocka S, Voglreiter P, Dokter M, Hofmann M, Kainz B, Hann A, Chen X, Alhonnoro T, Pollari M, Schmalstieg D, Moche M - Sci Rep (2015)

Schematic view of the liver (brown) with a fully expanded and umbrella-shaped radiofrequency ablation (RFA) needle (black).The needle tips are located in a liver tumor (red) surrounded by the so called necrotic zone (light brown).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4612735&req=5

f1: Schematic view of the liver (brown) with a fully expanded and umbrella-shaped radiofrequency ablation (RFA) needle (black).The needle tips are located in a liver tumor (red) surrounded by the so called necrotic zone (light brown).
Mentions: Liver cancer is on the rise worldwide, mainly because of hepatitis infection and alcohol abuse. Especially patients with primary liver cancer (Hepatocellular Carcinomas, HCC) have a poor prognosis because, of its late symptomatic onset, resulting in a median survival time of four to six months from the time of diagnosis, when untreated. According to the recent treatment guidelines1, radiofrequency ablation (RFA) serves as a first line therapy approach for early HCC in patients with liver cirrhosis. Also, for metastatic liver disease, the local usage of ablation therapies increases. While the technique was originally developed for patients who were not eligible for surgery its use has now expanded to serve as a bridge to liver transplantation and even as an alternative to surgical resection in the early stages of the disease2. RFA was first described in the early 1990s, followed by huge technical advances throughout the last decades. The underlying principle is based on a high frequency alternating current, which is delivered through one or more electrodes in the treated lesion3 (see Fig. 1 for a schematic view of RFA needle placement in a liver tumor, including the surrounding necrotic zone, and Fig. 2 for a postinterventional computed tomography (CT) scan with ablation needle). Optimally, the heat destroys cancer cells by inducing a coagulative necrosis, with cellular proteins being denaturized. Most commonly, tissue necrosis already begins at approximately 60 °C, but usually, temperatures around 100° are needed to achieve satisfying results. The amount of destroyed tissue mostly depends on the individual impedance and placement of the needle. Furthermore, it is inversely proportional to the square of the distance from the electrode. As a result, tissue cools rapidly away from the tip of the needle probe. Hence, the proximity to large blood vessels also plays a major role in the heat transmission. Blood flow protects the vessel wall from damage, but, on the flipside, acts as a heat sink by cooling down nearby tissue limiting the methods overall success4. As a consequence, a significant mismatch between expected and truly induced lesion size and geometry has been observed in many radio-frequency ablations performed in the liver. It can lead to over-treatment with severe injuries (up to 9% major complications5), or under-treatment with tumor recurrence (up to 40%5).

Bottom Line: For the quantitative and qualitative analysis of the algorithm's results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other).The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation.The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University, Rakentajanaukio 2 C, 02150 Espoo, Finland.

ABSTRACT
Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm's results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.

No MeSH data available.


Related in: MedlinePlus