Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

Wu, Po-Hung; Brace, Christopher L.

doi:10.1088/0031-9155/61/16/6041

Cited by 4 publications

(9 citation statements)

References 39 publications

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“…In 12 animal studies, the effects of microwave ablation in in vivo liver parenchyma were analyzed [8–11, 14, 15, 18, 19, 26–28, 34]. Gockner et al compared MWA using system A (Acculis) with and without transarterial embolization before ablation in sheep [19].…”

Section: Resultsmentioning

confidence: 99%

Liver microwave ablation: a systematic review of various FDA-approved systems

2018

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Objectives The aim of the present study is to analyze preclinical and clinical data on the performance of the currently US Food and Drug Administration (FDA)–approved microwave ablation (MWA) systems. Methods A review of the literature, published between January 1, 2005, and December 31, 2016, on seven FDA-approved MWA systems, was conducted. Ratio of ablation zone volume to applied energy R(AZ:E) and sphericity indices were calculated for ex vivo and in vivo experiments. Results Thirty-four studies with ex vivo, in vivo, and clinical data were summarized. In total, 14 studies reporting data on ablation zone volume and applied energy were included for comparison R(AZ:E). A significant correlation between volume and energy was found for the ex vivo experiments ( r = 0.85, p < 0.001) in contrast to the in vivo experiments ( r = 0.54, p = 0.27). Conclusion Manufacturers’ algorithms on microwave ablation zone sizes are based on preclinical animal experiments with normal liver parenchyma. Clinical data reporting on ablation zone volume in relation to applied energy and sphericity index during MWA are scarce and require more adequate reporting of MWA data. Key Points • Clinical data reporting on the ablation zone volume in relation to applied energy during microwave ablation are scarce. • Manufacturers’ algorithms on microwave ablation zone sizes are based on preclinical animal experiments with normal liver parenchyma. • Preclinical data do not predict actual clinical ablation zone volumes in patients with liver tumors.

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Section: Resultsmentioning

confidence: 99%

Liver microwave ablation: a systematic review of various FDA-approved systems

2018

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“…Data collection, processing, and analysis methods described herein are similar to those outlined in prior work. 19,34 Overlapping methodology is reproduced here to provide greater clarity.…”

Section: Methodsmentioning

confidence: 99%

“…10 Serial low-dose CECT is also a feasible intra-procedural technique even if trapped contrast material may slightly reduce ablation boundary contrast. 19 The most common method of segmenting ablation zones from CT imaging is to manually delineate the hypodense region surrounding the ablation applicator. However, manual delineation is not feasible during a real-time monitoring protocol.…”

Section: Introductionmentioning

confidence: 99%

Feature‐based automated segmentation of ablation zones by fuzzy c‐mean clustering during low‐dose computed tomography

Bedoya

White

et al. 2020

Medical Physics

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Intra-procedural monitoring and post-procedural follow-up is necessary for a successful ablation treatment. An imaging technique which can assess the ablation geometry accurately is beneficial to monitor and evaluate treatment. In this study, we developed an automated ablation segmentation technique for serial low-dose, noisy ablation computed tomography (CT) or contrast-enhanced CT (CECT). Methods: Low-dose, noisy temporal CT and CECT volumes were acquired during microwave ablation on normal porcine liver (four with non-contrast CT and eight with CECT). Highly constrained backprojection (HYPR) processing was used to recover ablation zone information compromised by low-dose noise. First-order statistic features and normalized fractional Brownian features (NBF) were used to segment ablation zones by fuzzy c-mean clustering. After clustering, the segmented ablation zone was refined by cyclic morphological processing. Automatic and manual segmentations were compared to gross pathology with Dice's coefficient (morphological similarity), while cross-sectional dimensions were compared by percent difference. Results: Automatic and manual segmentations of the ablation zone were very similar to gross pathology (Dice Coefficients: Auto.-Path. = 0.84 AE 0.02; Manu.-Path. = 0.76 AE 0.03, P = 0.11). The differences in ablation area, major diameter and minor diameter were 17.9 AE 3.2%, 11.1 AE 3.2% and 16.2 AE 3.4%, respectively, when comparing automatic segmentation to gross pathology, which were lower than the differences of 32.9 AE 16.8%, 13.0 AE 9.8% and 21.8 AE 5.8% when comparing manual segmentation to gross pathology. Manual segmentations tended to overestimate gross pathology when ablation area was less than 15 cm 2 , but the automated segmentation tended to underestimate gross pathology when ablation zone is larger than 20 cm 2. Conclusion: Fuzzy c-means clustering may be used to aid automatic segmentation of ablation zones without prior information or user input, making serial CT/CECT has more potential to assess treatments intra-procedurally.

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“…Schena et al derived the relationship between Hounsfield units (HU) and temperature by experiments and then utilized it in real‐time temperature monitoring of laser ablation . When using contrast, some of the iodine may become trapped in the ablation zone, slightly affecting visualization of the ablation zone but does not preclude the use of serial CT for ablation monitoring …”

Section: Introductionmentioning

confidence: 99%

“…23 When using contrast, some of the iodine may become trapped in the ablation zone, slightly affecting visualization of the ablation zone but does not preclude the use of serial CT for ablation monitoring. 24 Maintaining a total radiation dose and iodinated contrast load at or below conventional abdominal CT levels is an important objective to allow for wider adoption of serial CT for ablation monitoring. Since reductions in both radiation and iodine dose will degrade image quality, techniques to recover the lost information and render imaging volumes suitable for assessment of the ablation zone growth are necessary.…”

Section: Introductionmentioning

confidence: 99%

Ablation zone visualization enhancement by periodic contrast-enhancement computed tomography during microwave ablation

Borden

Brace

2017

Med. Phys.

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Purpose Intra-procedural contrast-enhanced computed tomography (CECT) has been proposed to monitor the growth of ablation zone in order to evaluate the efficacy of microwave ablation more accurately than post-ablation image. However, the dilemma of keeping image quality or following dose regulation becomes a huge challenge to apply CECT in real-time monitoring. The purpose of this study is to evaluate the feasibility of applying local highly constrained backprojection reconstruction (HYPR-LR) on periodic CECT image to enhance visualization of ablation zone by statistical and pathological- radiological analysis. Methods Low-dose ( CTDIvol≤1.49 italicmGy), temporal CECT volumes were acquired during microwave ablation on normal porcine liver. HYPR processing was performed on each volume after image registration. Ablation signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were collected to evaluate the degree of enhancement of image quality and ablation zone visualization. Ablation zone was manually segmented on HYPR and non-HYPR images and compared the similarity to gross pathology by measuring Dice coefficient. The dimension of ablation zone was also compared to gross pathology by correlation and measurement difference. Results The SNR and CNR of ablation zone were increased after involving certain slices into HYPR processing. The manually segmented ablation zone was highly similar to gross pathology with DICE coefficient 0.81±0.03, while the low-dose CECT had smaller DICE coefficient with 0.72±0.05. Both HYPR image and low-dose CECT has high correlation coefficient to gross pathology with 0.99 and 0.94, but the variance of measurements were less on HYPR image than those on unprocessed images. The relative difference in area, length of long axis and short axis for HYPR image were 13.1±5.6%, 9.7±4.2% and 15.2±2.8 %, which were less than those for low-dose CECT with 37.5±6.0%, 17.7±2.8% and 28.9±5.4%. Conclusion HYPR processing applied to periodic CECT images can enhance ablation zone visualization. HYPR processing may potentially enable CECT in real-time ablation monitoring under strict regulation of radiation dose.

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Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

Cited by 4 publications

References 39 publications

Liver microwave ablation: a systematic review of various FDA-approved systems

Liver microwave ablation: a systematic review of various FDA-approved systems

Feature‐based automated segmentation of ablation zones by fuzzy c‐mean clustering during low‐dose computed tomography

Ablation zone visualization enhancement by periodic contrast-enhancement computed tomography during microwave ablation

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