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Alexander

3 records found

Authored

Intraprocedural assessment of ablation margins using computed tomography co-registration in hepatocellular carcinoma treatment with percutaneous ablation

IAMCOMPLETE study

Journal article (2023) - P. Hendriks, Kiki M. van Dijk, Bas Boekestijn, Alexander Broersen, Jacoba J. van Duijn-de Vreugd, Minneke J. Coenraad, J. Dijkstra, L.F. de Geus-Oei, L.F. de Geus-Oei, L.F. de Geus-Oei, M.C. Burgmans, None More Authors

Purpose: The primary objective of this study was to determine the feasibility of ablation margin quantification using a standardized scanning protocol during thermal ablation (TA) of hepatocellular carcinoma (HCC), and a rigid registration algorithm. Secondary objectives were to determine the inter- and intra-observer variability of tumor segmentation and quantification of the minimal ablation margin (MAM). Materials and methods: Twenty patients who underwent thermal ablation for HCC were included. There were thirteen men and seven women with a mean age of 67.1 ± 10.8 (standard deviation [SD]) years (age range: 49.1–81.1 years). All patients underwent contrast-enhanced computed tomography examination under general anesthesia directly before and after TA, with preoxygenated breath hold. Contrast-enhanced computed tomography examinations were analyzed by radiologists using rigid registration software. Registration was deemed feasible when accurate rigid co-registration could be obtained. Inter- and intra-observer rates of tumor segmentation and MAM quantification were calculated. MAM values were correlated with local tumor progression (LTP) after one year of follow-up. Results: Co-registration of pre- and post-ablation images was feasible in 16 out of 20 patients (80%) and 26 out of 31 tumors (84%). Mean Dice similarity coefficient for inter- and intra-observer variability of tumor segmentation were 0.815 and 0.830, respectively. Mean MAM was 0.63 ± 3.589 (SD) mm (range: -6.26–6.65 mm). LTP occurred in four out of 20 patients (20%). The mean MAM value for patients who developed LTP was -4.00 mm, as compared to 0.727 mm for patients who did not develop LTP. Conclusion: Ablation margin quantification is feasible using a standardized contrast-enhanced computed tomography protocol. Interpretation of MAM was hampered by the occurrence of tissue shrinkage during TA. Further validation in a larger cohort should lead to meaningful cut-off values for technical success of TA.

@en

Contributed

Thermal ablation of primary liver tumors: Correspondence of the predicted ablation zone with the clinically obtained ablation zone

Master thesis (2022) - G.C.M. van Erp, Mark Burgmans, Alexander Broersen, Pim Hendriks, Stefan Klein, Roderick Scherptong

Purpose Manufacturer’s predictions of ablation zone dimensions are the current directives for treatment planning in thermal ablation, while they are mostly based on ex vivo experiments making its reliability questionable. The aim of this study is to determine the correspondence in dimensions, volume, shape and overlap of the manufactures’ predicted with the clinically realized ablation zones following thermal ablation of hepatocellular carcinoma (HCC). The secondary objective is to determine the effect of tumor- and liver characteristics on this correspondence.
Methods Data was retrospectively collected from two prospective studies. A registered pre-ablation and post-ablation computed tomography scan with liver, tumor and ablation zone segmentations were available for analysis. Needle position reconstruction was performed based on image visual assessment (e.g., gas formation, tumor location and subcapsular hemorrhage) using in-house developed software. The dimensions of the predicted ablation zone were derived from the manufacturer’s chart corresponding to treatment settings used during ablation. The long axis diameter (LAD), short axis diameter (SAD) and volume of the realized and predicted ablation zone were compared. The overlap was determined using the Dice similarity coefficient (DSC) and the average surface deviation between the realized and predicted ablation zone. The effect of tumor location, vascular proximity and liver cirrhosis on the overlap was quantified using the DSC and average surface deviation.
Results Nineteen patients and 21 ablations were included for analysis. The median realized volume did not significantly differ from the predicted volume, 25.7 cm3 and 22.6 cm3 respectively (p = 0.526). The median LAD and SAD of the realized ablation zone differed significantly from the manufacturer’s prediction (51.9 mm vs 40.0 mm, p<0.001 and 36.9 mm vs 35.0 mm, p<0.001 respectively). The predicted ablation zone corresponds to the realized ablation zone with a mean DSC of 0.73 and mean average surface deviation of 3.04 mm. Tumor location and vascular proximity did not affect the overlap between the realized and predicted ablation zone. The effect of liver cirrhosis was not assessed due to a low sample size of HCC in a non-cirrhotic liver (n=2).
Conclusion The manufacturer’s predicted volume of liver ablation zones corresponds well to the clinically realized ablation volume. However, the LAD and SAD are underestimated by the manufacturers. The shape and overlap of the predicted and realized ablation zone were sufficient. Further studies evaluating the effect of tumor- and liver characteristics on the correspondence of the predicted with the realized ablation zone with a larger patient cohort is needed.

Quantitative three-dimensional evaluation of ablation margins for the prediction of local tumor progression

Master thesis (2020) - F.D.E.M. Boel, Mark Burgmans, Jouke Dijkstra, Pim Hendriks, Alexander Broersen

Introduction The objective of this research is to assess whether there is a correlation between quantitatively assessed ablation margins and the occurrence of local tumor progression (LTP) using dedicated image processing software.
Methods 28 patients with 45 de ...