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Li X, Jia X, Shen T, Wang M, Yang G, Wang H, Sun Q, Wan M, Zhang S. Ultrasound Entropy Imaging for Detection and Monitoring of Thermal Lesion During Microwave Ablation of Liver. IEEE J Biomed Health Inform 2022; 26:4056-4066. [PMID: 35417359 DOI: 10.1109/jbhi.2022.3167252] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Ultrasonic B-mode imaging offers non-invasive and real-time monitoring of thermal ablation treatment in clinical use, however it faces challenges of moderate lesion-normal contrast and detection accuracy. Quantitative ultrasound imaging techniques have been proposed as promising tools to evaluate the microstructure of ablated tissue. In this study, we introduced Shannon entropy, a non-model based statistical measurement of disorder, to quantitatively detect and monitor microwave-induced ablation in porcine livers. Performance of typical Shannon entropy (TSE), weighted Shannon entropy (WSE), and horizontally normalized Shannon entropy (hNSE) were explored and compared with conventional B-mode imaging. TSE estimated from non-normalized probability distribution histograms was found to have insufficient discernibility of different disorder of data. WSE that improves from TSE by adding signal amplitudes as weights obtained area under receiver operating characteristic (AUROC) curve of 0.895, whereas it underestimated the periphery of lesion region. hNSE provided superior ablated area prediction with the correlation coefficient of 0.90 against ground truth, AUROC of 0.868, and remarkable lesion-normal contrast with contrast-to-noise ratio of 5.86 which was significantly higher than other imaging methods. Data distributions shown in horizontally normalized probability distribution histograms indicated that the disorder of backscattered envelope signal from ablated region increased as treatment went on. These findings suggest that hNSE imaging could be a promising technique to assist ultrasound guided percutaneous thermal ablation.
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Pohlman RM, Hinshaw JL, Ziemlewicz TJ, Lubner MG, Wells SA, Lee FT, Alexander ML, Wergin KL, Varghese T. Differential Imaging of Liver Tumors before and after Microwave Ablation with Electrode Displacement Elastography. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:2138-2156. [PMID: 34011451 PMCID: PMC8243838 DOI: 10.1016/j.ultrasmedbio.2021.03.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 03/18/2021] [Accepted: 03/23/2021] [Indexed: 05/17/2023]
Abstract
Liver cancer is a leading cause of cancer-related deaths; however, primary treatment options such as surgical resection and liver transplant may not be viable for many patients. Minimally invasive image-guided microwave ablation (MWA) provides a locally effective treatment option for these patients with an impact comparable to that of surgery for both cancer-specific and overall survival. MWA efficacy is correlated with accurate image guidance; however, conventional modalities such as B-mode ultrasound and computed tomography have limitations. Alternatively, ultrasound elastography has been used to demarcate post-ablation zones, yet has limitations for pre-ablation visualization because of variability in strain contrast between cancer types. This study attempted to characterize both pre-ablation tumors and post-ablation zones using electrode displacement elastography (EDE) for 13 patients with hepatocellular carcinoma or liver metastasis. Typically, MWA ablation margins of 0.5-1.0 cm are desired, which are strongly correlated with treatment efficacy. Our results revealed an average estimated ablation margin inner quartile range of 0.54-1.21 cm with a median value of 0.84 cm. These treatment margins lie within or above the targeted ablative margin, indicating the potential to use EDE for differentiating index tumors and ablated zones during clinical ablations. We also obtained a high correlation between corresponding segmented cross-sectional areas from contrast-enhanced computed tomography, the current clinical gold standard, when compared with EDE strain images, with r2 values of 0.97 and 0.98 for pre- and post-ablation regions.
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Affiliation(s)
- Robert M Pohlman
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
| | - James L Hinshaw
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Timothy J Ziemlewicz
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Meghan G Lubner
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Shane A Wells
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Fred T Lee
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Marci L Alexander
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Kelly L Wergin
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Tomy Varghese
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
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Martelletti C, Armandi A, Caviglia GP, Saracco GM, Pellicano R. Elastography for characterization of focal liver lesions: current evidence and future perspectives. Minerva Gastroenterol (Torino) 2020; 67:196-208. [PMID: 32677420 DOI: 10.23736/s2724-5985.20.02747-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Focal liver lesions (FLLs) are a common finding during routine abdominal ultrasound (US). The differential diagnosis between diverse types of FLLs, especially between benign and malignant ones, is extremely important and can often be particularly challenging. Radiological techniques with contrast administration and/or liver biopsy are mostly necessary for establishing diagnosis, but they have several contraindications or complications. Due to limitations of these tools, there is urgent and still unmet need to develop a first line, non-invasive and simple method to diagnose FLLs. Elastography is an US-based imaging modality that provides information about the physical parameter corresponding to the tissue stiffness and can be considered a virtual biopsy. Several elastographic approaches have been developed, such as transient elastography, strain imaging and share wave imaging, which include point shear wave elastography and 2D shear wave elastography. These tools are already in use for evaluating liver fibrosis and in the assessment of focal lesions in other organs, like breast and thyroid gland. This review aims to assess the current evidence of different techniques based on elastography in the setting of FLLs, in order to evaluate accuracy, limitations and future perspectives. In particular, we focused on two contexts: the ability of discriminating between benign and malignant lesions, especially hepatocellular carcinoma and liver metastasis, and the surveillance after percutaneous therapy. This could have a high clinical impact making elastography crucial to identify the appropriate management of FLLs.
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Affiliation(s)
- Carolina Martelletti
- School of Gastroenterology, Department of Medical Sciences, University of Turin, Turin, Italy
| | - Angelo Armandi
- School of Gastroenterology, Department of Medical Sciences, University of Turin, Turin, Italy
| | | | - Giorgio M Saracco
- School of Gastroenterology, Department of Medical Sciences, University of Turin, Turin, Italy.,Department of Medical Sciences, University of Turin, Turin, Italy.,Unit of Gastroenterology, Molinette-SGAS Hospital, Turin, Italy
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Ingle AN, Varghese T. A kernel smoothing algorithm for ablation visualization in ultrasound elastography. ULTRASONICS 2019; 96:267-275. [PMID: 30723026 PMCID: PMC6541505 DOI: 10.1016/j.ultras.2018.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/10/2018] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
Three-dimensional visualization of tumor ablation procedures have significant clinical value because the ability to accurately visualize ablated volumes can help clinicians gauge the extent of ablated tissue necrosis and plan future treatment steps. Better control over ablation volume can prevent recurrence of tumors treated using ablative procedures. This paper presents a kernel based smoothing algorithm called MatérnSmooth to reconstruct shear wave velocity maps from data acquired through ultrasound electrode vibration elastography. Shear wave velocity estimates are acquired on several intersecting imaging planes that share a common axis of intersection collinear with the ablation needle. An objective method of choosing smoothing parameters from underlying data is outlined through simulations. Experimental validation was performed on data acquired from a tissue mimicking phantom. Volume estimates were found to be within 20% of the true value.
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Affiliation(s)
- Atul N Ingle
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA; Department of Electrical and Computer Engineering, University of Wisconsin - Madison, Madison, WI 53705, USA.
| | - Tomy Varghese
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA; Department of Electrical and Computer Engineering, University of Wisconsin - Madison, Madison, WI 53705, USA.
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Pohlman RM, Turney MR, Wu P, Brace CL, Ziemlewicz TJ, Varghese T. Two-dimensional ultrasound-computed tomography image registration for monitoring percutaneous hepatic intervention. Med Phys 2019; 46:2600-2609. [PMID: 31009079 PMCID: PMC6758542 DOI: 10.1002/mp.13554] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 04/14/2019] [Accepted: 04/15/2019] [Indexed: 01/03/2023] Open
Abstract
PURPOSE Deformable registration of ultrasound (US) and contrast enhanced computed tomography (CECT) images are essential for quantitative comparison of ablation boundaries and dimensions determined using these modalities. This comparison is essential as stiffness-based imaging using US has become popular and offers a nonionizing and cost-effective imaging modality for monitoring minimally invasive microwave ablation procedures. A sensible manual registration method is presented that performs the required CT-US image registration. METHODS The two-dimensional (2D) virtual CT image plane that corresponds to the clinical US B-mode was obtained by "virtually slicing" the 3D CT volume along the plane containing non-anatomical landmarks, namely points along the microwave ablation antenna. The initial slice plane was generated using the vector acquired by rotating the normal vector of the transverse (i.e., xz) plane along the angle subtended by the antenna. This plane was then further rotated along the ablation antenna and shifted along with the direction of normal vector to obtain similar anatomical structures, such as the liver surface and vasculature that is visualized on both the CT virtual slice and US B-mode images on 20 patients. Finally, an affine transformation was estimated using anatomic and non-anatomic landmarks to account for distortion between the colocated CT virtual slice and US B-mode image resulting in a final registered CT virtual slice. Registration accuracy was measured by estimating the Euclidean distance between corresponding registered points on CT and US B-mode images. RESULTS Mean and SD of the affine transformed registration error was 1.85 ± 2.14 (mm), computed from 20 coregistered data sets. CONCLUSIONS Our results demonstrate the ability to obtain 2D virtual CT slices that are registered to clinical US B-mode images. The use of both anatomical and non-anatomical landmarks result in accurate registration useful for validating ablative margins and comparison to electrode displacement elastography based images.
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Affiliation(s)
- Robert M. Pohlman
- Department of Medical PhysicsUniversity of Wisconsin School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Michael R. Turney
- Department of Medical PhysicsUniversity of Wisconsin School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Po‐Hung Wu
- Department of RadiologyUniversity of Wisconsin School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Christopher L. Brace
- Department of RadiologyUniversity of Wisconsin School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Timothy J. Ziemlewicz
- Department of RadiologyUniversity of Wisconsin School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI53706USA
| | - Tomy Varghese
- Department of Medical PhysicsUniversity of Wisconsin School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI53706USA
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Strigari L, Minosse S, D'Alessio D, Farina L, Cavagnaro M, Cassano B, Pinto R, Vallati G, Lopresto V. Microwave thermal ablation using CT-scanner for predicting the variation of ablated region over time: advantages and limitations. Phys Med Biol 2019; 64:115021. [PMID: 30995620 DOI: 10.1088/1361-6560/ab1a67] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This study aims at investigating in real-time the structural and dynamical changes occurring in an ex vivo tissue during a microwave thermal ablation (MTA) procedure. The experimental set-up was based on ex vivo liver tissue inserted in a dedicated box, in which 3 fibre-optic (FO) temperature probes were introduced to measure the temperature increase over time. Computed tomography (CT) imaging technique was exploited to experimentally study in real-time the Hounsfield Units (HU) modification occurring during MTA. The collected image data were processed with a dedicated MATLAB tool, developed to analyse the FO positions and HU modifications from the CT images acquired over time before and during the ablation procedures. The radial position of a FO temperature probe (rFO) and the value of HU in the region of interest (ROI) containing the probe (HUo), along with the corresponding value of HU in the contralateral ROI with respect to the MTA antenna applicator (HUc), were determined and registered over time during and after the MTA procedure. Six experiments were conducted to confirm results. The correlation between temperature and the above listed predictors was investigated using univariate and multivariate analysis. At the multivariate analysis, the time, rFO and HUc resulted significant predictive factors of the logarithm of measured temperature. The correlation between predicted and measured temperatures was 0.934 (p < 0.001). The developed tool allows identifying and registering the image-based parameters useful for predicting the temperature variation over time in each investigated voxel by taking into consideration the HU variation.
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Affiliation(s)
- L Strigari
- Laboratory of Medical Physics and Expert Systems, IRCCS Regina Elena National Cancer Institute, IFO, via Elio Chianesi, 53, 00144, Rome, Italy. Current address: Department of Medical Physics, St. Orsola-Malpighi University Hospital, via Massarenti 9 40138 Bologna, Italy
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Pohlman RM, Varghese T, Jiang J, Ziemlewicz TJ, Alexander ML, Wergin KL, Hinshaw JL, Lubner MG, Wells SA, Lee FT. Comparison of Displacement Tracking Algorithms for in Vivo Electrode Displacement Elastography. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:218-232. [PMID: 30318122 PMCID: PMC6324563 DOI: 10.1016/j.ultrasmedbio.2018.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/21/2018] [Accepted: 09/03/2018] [Indexed: 05/09/2023]
Abstract
Hepatocellular carcinoma and liver metastases are common hepatic malignancies presenting with high mortality rates. Minimally invasive microwave ablation (MWA) yields high success rates similar to surgical resection. However, MWA procedures require accurate image guidance during the procedure and for post-procedure assessments. Ultrasound electrode displacement elastography (EDE) has demonstrated utility for non-ionizing imaging of regions of thermal necrosis created with MWA in the ablation suite. Three strategies for displacement vector tracking and strain tensor estimation, namely coupled subsample displacement estimation (CSDE), a multilevel 2-D normalized cross-correlation method, and quality-guided displacement tracking (QGDT) have previously shown accurate estimations for EDE. This paper reports on a qualitative and quantitative comparison of these three algorithms over 79 patients after an MWA procedure. Qualitatively, CSDE presents sharply delineated, clean ablated regions with low noise except for the distal boundary of the ablated region. Multilevel and QGDT contain more visible noise artifacts, but delineation is seen over the entire ablated region. Quantitative comparison indicates CSDE with more consistent mean and standard deviations of region of interest within the mass of strain tensor magnitudes and higher contrast, while Multilevel and QGDT provide higher CNR. This fact along with highest success rates of 89% and 79% on axial and lateral strain tensor images for visualization of thermal necrosis using the Multilevel approach leads to it being the best choice in a clinical setting. All methods, however, provide consistent and reproducible delineation for EDE in the ablation suite.
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Affiliation(s)
- Robert M Pohlman
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Tomy Varghese
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA; Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
| | - Jingfeng Jiang
- Department of Biomedical Engineering, Michigan Technological University, Houghton, Michigan, USA
| | - Timothy J Ziemlewicz
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Marci L Alexander
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Kelly L Wergin
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - James L Hinshaw
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Meghan G Lubner
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Shane A Wells
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Fred T Lee
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
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Pohlman RM, Varghese T. Dictionary Representations for Electrode Displacement Elastography. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2018; 65:2381-2389. [PMID: 30296219 PMCID: PMC6400457 DOI: 10.1109/tuffc.2018.2874181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Ultrasound electrode displacement elastography (EDE) has demonstrated the potential to monitor ablated regions in human patients after minimally invasive microwave ablation procedures. Displacement estimation for EDE is commonly plagued by decorrelation noise artifacts degrading displacement estimates. In this paper, we propose a global dictionary learning approach applied to denoising displacement estimates with an adaptively learned dictionary from EDE phantom displacement maps. The resulting algorithm is one that represents displacement patches sparsely if they contain low noise and averages remaining patches thereby denoising displacement maps while retaining important edge information. The results of dictionary-represented displacements presented with a higher signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) with improved contrast, as well as improved phantom inclusion delineation when compared to initial displacements, median-filtered displacements, and spline smoothened displacements, respectively. In addition to visualized noise reduction, dictionary-represented displacements presented with the highest SNR, CNR, and improved contrast with values of 1.77, 4.56, and 4.35 dB, respectively, when compared to axial strain tensor images estimated using the initial displacements. Following EDE phantom imaging, we utilized dictionary representations from in vivo patient data, further validating efficacy. Denoising displacement estimates are a newer application for dictionary learning producing strong ablated region delineation with little degradation from denoising.
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