Volume and Shape Assessment of Renal Radiofrequency Ablation Lesion

Abreu, L.; Damasceno-Ferreira, José Aurelino; Monteiro, Maria Eduarda; Pereira‐Sampaio, Marco A.; Sampaio, Francisco J.B.; Souza, Diogo Benchimol de

doi:10.1016/j.urology.2018.03.015

Cited by 4 publications

(5 citation statements)

References 27 publications

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“…Specifically, we observed that there were increases in diameter as well as increases in sphericity compared to prior reports for 3-5 cm tip exposures. Indeed, the lack of sphericity (i.e., the creation of oblong shaped zones of ablation) has been reported as an issue for many RF and microwave systems [19,20]. However, our study suggests that with more optimal RF current delivery more optimal energy distribution is possible thus resulting in greater spherical shape of ablation.…”

Section: Discussionmentioning

confidence: 58%

Optimization and characterization of a novel internally-cooled radiofrequency ablation system with optimized pulsing algorithm in an ex-vivo bovine liver

Ben-David

Nissenbaum

Gurevich

et al. 2019

International Journal of Hyperthermia

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Purpose: To prospectively characterize and optimize radiofrequency energy deposition to determine ideal parameters for achieving large ablation zones. Materials and methods: An internally-cooled RF system was used to perform 214 ablations in 72 exvivo bovine livers. Tip exposure (1-5 cm), electrode current (400-2500 mA), and application duration (3-15 min) were systematically varied. A pulsing algorithm optimized efficiency of RF deposition, including initial automatic ramping followed by adjustment in current, in response to changes in tissue impedance. Following the procedure ablation diameter and length were measured, sphericity calculated, and correlated with parameters of energy deposition and tissue temperatures. Results: Increasing electrode exposure from 1-5 cm produced linear increases in ablation diameter from 1.4 ± 0.1 to 5.3 ± 0.1 cm (y ¼ 1.1x-0.5; R 2 ¼ 0.93), and length (y ¼ 1.18x þ 0.34; R 2 ¼ 0.92). A sphericity index >0.85 was noted at optimal energy setting for electrode exposures of 1-4 cm. Maximum temperatures post-ablation increased with active tip length from 68.5 ± 4.9 C to 91.3 ± 1.5 C in a logarithmic (y ¼ 0.94ln(x)À2.75; R 2 ¼ 0.90) or power relationship between temperature and the resultant ablation diameter (y ¼ 0.27e 0.0295x ; R 2 ¼ 0.76). A tight exponential relationship (y ¼ 0.28x 0.38; R 2 ¼ 0.97) was also observed between total energy deposition and ablation diameter. Finally, a multifactor relationship of the diameter of ablation to electrode tip exposure and the time to first impedance rise was successfully modeled, with a root mean squared error of 1.9 mm and R 2 ¼ 0.95. Conclusion: Large, reproducible, and spherical ablation areas can be achieved with the novel system described, with efficient delivery of RF energy deposited into tissue. These findings may have important clinical relevance in regards to the clinical utility of RF ablation compared to other competitive forms of thermal tumor ablation.

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Section: Discussionmentioning

confidence: 58%

Optimization and characterization of a novel internally-cooled radiofrequency ablation system with optimized pulsing algorithm in an ex-vivo bovine liver

Ben-David

Nissenbaum

Gurevich

et al. 2019

International Journal of Hyperthermia

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“…Median TTP was also similar between the MWA and RFA Groups in both diagnoses, in particular 27 months [95% CI [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] ] (p = 0.925), for MT. There were no differences in overall survival between groups in both diagnoses.…”

Section: Assessed For Eligibility (N=145)mentioning

confidence: 78%

“…The primary endpoint was SLR 19 assessment and the secondary endpoints were TS (at the one-month control scan) and the cumulative incidence of LTP after 2 years of follow-up, The main study outcomes were also sphericity ratio (SR), surface area of the ablation zone 36 and the coefficient of variation (CV) 26 , 37 as a measure of reproducibility. SR referred to ratio of axial diameter to the average of the two transverse diameters of the ablation zone and closer to 1 implies greater sphericity 37 .…”

Section: Methodsmentioning

confidence: 99%

Microwave versus radiofrequency ablation for the treatment of liver malignancies: a randomized controlled phase 2 trial

Radosevic

Quesada

Serlavos

et al. 2022

Sci Rep

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Microwave (MWA) and radiofrequency ablation (RFA) are main ablative techniques for hepatocellular carcinoma (HCC) and colorectal liver metastasis (MT). This randomized phase 2 clinical trial compares the effectiveness of MWA and RFA as well as morphology of corresponding ablation zones. HCC and MT patients with 1.5–4 cm tumors, suitable for ablation, were randomized into MWA or RFA Groups. The primary endpoint was short-to-long diameter ratio of ablation zone (SLR). Primary technical success (TS) and a cumulative local tumor progression (LTP) after a median 2-year follow-up were compared. Between June 2015 and April 2020, 82 patients were randomly assigned (41 patients per group). For the per-protocol analysis, five patients were excluded. MWA created larger ablation zones than RFA (p = 0.036) although without differences in SLR (0.5 for both groups, p = 0.229). The TS was achieved in 98% (46/47) and 90% (45/50) (p = 0.108), and LTP was observed in 21% (10/47) vs. 12% (6/50) (OR 1.9 [95% CI 0.66–5.3], p = 0.238) of tumors in MWA vs. RFA Group, respectively. Major complications were found in 5 cases (11%) vs. 2 cases (4%), without statistical significance. MWA and RFA show similar SLR, effectiveness and safety in liver tumors between 1.5 and 4 cm.

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“…Pinsky et al (12) applied a similar technique for determining osseous defect sizes using 3D CBCT and suggested that clinically acceptable accuracy can be obtained with such a technique when performing volumetric analysis of small osseous defects of the human mandible. Moreover, Cavalieri's principle was also used in several other medical fields to assess the volume of lesions or to evaluate the regression of tumors after chemo-radiotherapy (21,22).…”

Section: Discussionmentioning

confidence: 99%

Comparative assessment of 3D reconstruction technique and Cavalieri’s principle in predicting the mandibular bone defect volumes

et al. 2019

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Comparative assessment of 3D reconstruction technique and Cavalieri's principle in predicting the mandibular bone defect volumes PurposeThe objective of this study was to compare the accuracy of the Cavalieri's principle and 3D reconstruction in predicting the volume of a bony defect. Materials and MethodsDefects of the same approximate size were created on nine artificial mandibles. The actual volume of the defect on each mandible was measured by water displacement, and served as the control. Each mandible was then scanned using a CBCT and volume measurements were made for each defect using two techniques: Cavalieri's principle and 3D reconstruction. For each defect, the volume obtained by each of the two techniques was compared to the control volume using the analysis of variances (ANOVA) with p<0.05. ResultsANOVA between the control, 3D reconstruction and Cavalieri's principle groups showed no statistically significant differences (p=.058). When the control group was further analyzed by Dunnett's post-hoc test, the results from Cavalieri's principle were found to be statistically different than the control group (p=.035), whereas the results of 3D reconstruction technique did not reach the level of significance (p=.523). ConclusionCavalieri's principle significantly underestimates the actual control volume, and is less accurate than the 3D reconstruction technique. The 3D reconstruction method is a reliable technique in measuring volume of bony defects.

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Volume and Shape Assessment of Renal Radiofrequency Ablation Lesion

Cited by 4 publications

References 27 publications

Optimization and characterization of a novel internally-cooled radiofrequency ablation system with optimized pulsing algorithm in an ex-vivo bovine liver

Optimization and characterization of a novel internally-cooled radiofrequency ablation system with optimized pulsing algorithm in an ex-vivo bovine liver

Microwave versus radiofrequency ablation for the treatment of liver malignancies: a randomized controlled phase 2 trial

Comparative assessment of 3D reconstruction technique and Cavalieri’s principle in predicting the mandibular bone defect volumes

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