Real-Time Elastography of Hepatic Thermal Lesions In Vitro: Histopathological Correlation

2011 ◽  
Vol 33 (02) ◽  
pp. 170-174 ◽  
Author(s):  
P. Wiggermann ◽  
E.-M. Jung ◽  
S. Glöckner ◽  
P. Hoffstetter ◽  
W. Uller ◽  
...  
Keyword(s):  
Real Time ◽  
Image Plane ◽  
Lesion Size ◽  
Lesion Detection ◽  
Porcine Liver ◽  
Thermal Lesion ◽  
Thermal Lesions ◽  
Histopathological Correlation ◽  
Thermal Therapies

Abstract Purpose: To evaluate the reliability of elastography, a new ultrasonographic method, for delineating thermal lesion boundaries in porcine liver tissue by comparing lesion dimensions determined by real-time elastography with the findings at gross pathology. Materials and Methods: A total of 15 thermal lesions with diameters ranging from 17 to 60 mm were created using radiofrequency ablation (RFA). Color-coded elastography was performed by one experienced examiner, using a 6 – 15 MHz high frequency linear transducer (LOGIQ E9, GE). Lesions were examined using B-mode and real-time elastography (RTE). Lesion detection, delineation and size were assessed using B-mode and RTE immediately after each thermal ablation ( < 5 min). Measurements of the sections representing the same image plane used for elastography were taken during pathologic examination and compared to the measurements obtained from the elastograms. Results: In our sample a statistically significant correlation in vitro between RTE and pathological measurements with respect to the lesion’s principal axis and area (r2 = 0.9338 long axis, r2 = 0.8998 short axis and r2 = 0.9676 area) was found. Overall, elastography slightly underestimated the lesion size, as judged by the digitalized pathologic images. Conclusion: These results support that RTE outperforms conventional B-mode ultrasound and could potentially be used for the routine assessment of thermal therapies.

Toward high-intensity focused ultrasound lesion quantification using compressive sensing theory

2017 ◽  
Vol 231 (12) ◽  
pp. 1152-1164
Author(s):  
Hadi Ghasemifard ◽  
Hamid Behnam ◽  
Jahan Tavakkoli
Keyword(s):  
Compressive Sensing ◽  
High Intensity ◽  
Wavelet Transforms ◽  
Focused Ultrasound ◽  
Lesion Detection ◽  
High Intensity Focused Ultrasound ◽  
Thermal Lesion ◽  
Thermal Lesions ◽  
Threshold Algorithm

Compressive sensing theory has in recent years been increasingly used in various pattern recognition applications. Compressive sensing theory makes it possible, under certain assumptions, to recover a signal or an image sampled below the Nyquist sampling limit. In this work, a new application of compressive sensing based on the threshold algorithm, in the area of controlling and monitoring of high-intensity focused ultrasound therapy, was investigated. In this work, a new method of high-intensity focused ultrasound lesion detection is presented based on a modified compressive sensing method in combination with the threshold algorithm and the wavelet transforms. In this study, analysis of the suggested method is performed using two sets of data: simulated and experimental ultrasound radio frequency data. The results of processing the data show that the proposed algorithm results in enhancement of the high-intensity focused ultrasound lesion contrast in comparison with the ultrasound B-mode and standard compressive sensing imaging methods. The results of the study show that the modified compressive sensing method could effectively detect thermal lesions in vitro. Comparing the estimated size of the thermal lesion (8.3 mm × 8.4 mm) using the proposed algorithm with the actual size of that from physical examination (10.1 mm × 9 mm) shows that we could detect high-intensity focused ultrasound thermal lesions with the difference of 0.8 mm × 0.5 mm.

Spatiotemporal Temperature Measurement Using Quantum Dot Thermometry During Nanoshell Mediated Thermal Therapy

2008 ◽  
Author(s):  
Bumsoo Han ◽  
Willard L. Hanson ◽  
Karim Bensalah ◽  
Altug Tuncel ◽  
Joshua Stern ◽  
...  
Keyword(s):  
Surgical Techniques ◽  
Thermal Therapy ◽  
Thermal Lesion ◽  
Major Drawback ◽  
Thermal Lesions ◽  
Minimally Invasive Surgical ◽  
Thermal Therapies ◽  
Diagnostic Technologies ◽  
Widespread Dissemination

Due to advances and routine use of various diagnostic technologies, tumors are increasingly detected at very early stages. Thus, there is growing interest in employing minimally invasive surgical techniques for the management of tumors. Many of these procedures are thermal therapies, in which localized thermal lesions, either hyperthermic or cryogenic, are created to destroy malignant tissue in situ. However, the major drawback to the widespread dissemination and acceptance of thermal therapy is the lack of a reliable real-time intraoperative monitoring technique of the thermal lesion.

scholarly journals Methodological parameters to induction of second-degree thermal injuries in experimental model

2018 ◽  
Vol 5 (11) ◽  
pp. 757-764
Author(s):  
Sabrina de Oliveira Capella ◽  
Mariana Teixeira Tillmann ◽  
Cristina Gevehr Fernandes ◽  
Márcio Fernando Weber Brito ◽  
Gabriela Morais Santana ◽  
...  
Keyword(s):  
High Temperatures ◽  
Companion Animals ◽  
Lesion Size ◽  
Thoracic Region ◽  
Thermal Lesion ◽  
Abdominal Region ◽  
Thermal Injuries ◽  
Lower Temperature ◽  
Second Degree

Thermal injuries present a high severity potential, affecting adjacent organs with functional loss and even methabolic, cardiovascular and pulmonary disorders that can lead the animal to death. Over time, companion animals started to share smaller spaces and living very close to humans, due to these changes cases of thermal burns have been increasing. Therefore, studies embracing this area are needed, considering the skin tissue and its attachments loss have repercussions in thequality of the wound healing. The complexity of this kind of skin injuries does not allow in vitro experiments to clarify its pathophysiology, being necessary to use experimental animals to replicate a thermal injury corectly, in the same way that we have a diversity of methodologies for inducing termal burns, and yet there is no such padronization for the development of a type of injury. In this scenario, the purpose of the study is to stablish methodological parameters for the induction of second-degree thermal lesions. Six Wistar rats were used, creating, with the help of cubic-tipped metallic device, two lesions on the back of each animal, one in the thoracic region and the other in the abdominal region. Different temperatures (90 oC and 100 oC) were applied in different times of contact with the skin (10 s, 15 s and 20 s), each animal received a temperature and time of exposure for both lesion sites. After three days the animals were euthanized, a photographic record was created and the injured skin sites were collected to evaluate the extent of the lesion by digital planimetry. Skin samples were processed and stained with hematoxicillin-eosin. It was observed that lesions in the abdominal region with higher temperature (100 oC) and longer exposure time (15 s and 20 s) showed an expansion in the diameter of the initial thermal lesion, whereas lesions of the thoracic region with lower temperature (90 oC) and time of exposure (10 s) showed a reduction related to the initial lesion size. Regarding the histopathological parameters, it was determined that wounds performed in the thoracic region and that remained longer in contact to high temperatures (90 oC and 100 oC) presented greater severity, whereas lesions located in the abdomen and with a shorter time of exposure to high temperatures were lower. Thus, it is concluded that to obtain standardized second-degree wounds it must be applied temperatures between 90 oC and 100 oC, for 15 s or 20 s, in the thoracic region.

Abstract 4113: In-Vitro Characterization of Ablation Lesions Using Oct

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Christine P Fleming ◽  
Lee M Barwick ◽  
Kara J Quan ◽  
Andrew M Rollins
Keyword(s):  
Real Time ◽  
Cardiac Tissue ◽  
Direct Method ◽  
Lesion Size ◽  
Three Dimensions ◽  
Necrotic Tissue ◽  
Triphenyltetrazolium Chloride ◽  
Tissue Samples ◽  
Oct Imaging

Radiofrequency ablation (RFA) is a clinical procedure that destroys tissue to cure cardiac arrhythmias. Presently, there is no direct method to monitor RFA lesion formation in real-time. Real time direct monitoring of the tissue could guide ablation and prevent complications such as tissue disruption that leads to perforation. Optical coherence tomography (OCT) provides real-time subsurface imaging with high spatial resolution in three dimensions. We hypothesized that OCT can distinguish necrotic ablated tissue from viable cardiac tissue. Freshly excised right ventricular wedges from swine were placed in a bath with phosphate buffered saline (PBS) maintained at 37°C with super-perfusion flow. RFA lesions were created with a temperature controlled (70°C) protocol, maximum delivered power of 50W for 10, 20, 30, and 60 seconds. Endocardial lesions were created using a 7Fr, 4mm tip RFA catheter. OCT imaging was conducted on a system with a 1310 nm light source and 10μm axial and 18 μm lateral resolution. Staining with 0.1% triphenyltetrazolium chloride in PBS for 15 minutes was used to confirm necrosis and quantify lesion size. The single scattering model of OCT images was used to extract three parameters (attenuation, backscattering, and correlation) to give an indication of tissue scattering, reflectivity, and heterogeneity respectively. OCT images of control (n=26) and ablated tissue (n=87) were analyzed with OCT. Viable tissue had a banding appearance due to the bifriengence property of highly organized myocardial tissue, absent in necrotic tissue caused by ablation. RFA lesions were characterized by increased imaging depth, increased scattering, and a heterogeneous appearance in OCT images. The real-time changes in tissue were detected after onset of ablation. 29 tissue samples had early detection of crater formation and tissue disruption before any adverse effect could occur. The correlation and attenuation coefficients of necrotic tissue were significantly smaller than viable tissue (p<0.01). Using OCT imaging, healthy endocardium and myocardium can be readily distinguished from necrotic tissue produced by RFA. This real-time monitoring may guide ablation by allowing the operator to see ablated tissue before an adverse event can occur.

Area Under the Real-Time Contact Force Curve (Force-Time Integral) Predicts Radiofrequency Lesion Size in an In Vitro Contractile Model

2010 ◽  
Vol 21 (9) ◽  
pp. 1038-1043 ◽  
Author(s):  
DIPEN C. SHAH ◽  
HENDRIK LAMBERT ◽  
HIROSHI NAKAGAWA ◽  
ARNE LANGENKAMP ◽  
NICOLAS AEBY ◽  
...  
Keyword(s):  
Real Time ◽  
Contact Force ◽  
Lesion Size ◽  
Force Curve ◽  
The Real ◽  
Time Integral ◽  
Radiofrequency Lesion ◽  
Force Time ◽  
Force Time Integral

Determination of Lesion Size as Function of HIFU Sonication Time Using MRI Monitored HIFU Ablations

2009 ◽  
Author(s):  
Subhashish Dasgupta ◽  
Janaka Wansapura ◽  
Prasanna Hariharan ◽  
Ron Pratt ◽  
David Witte ◽  
...  
Keyword(s):  
Focused Ultrasound ◽  
Ex Vivo ◽  
Acoustic Power ◽  
Lesion Size ◽  
High Intensity Focused Ultrasound ◽  
Numerical Calculations ◽  
Sonication Time ◽  
Porcine Liver ◽  
Thermal Lesion ◽  
Liver Sample

The purpose of this study is to determine the dependence of the size of the thermal lesion on sonication time in an ex-vivo porcine liver sample during simulated High Intensity Focused Ultrasound (HIFU) tissue ablation. MRI guided HIFU ablations were performed on a freshly excised porcine liver sample at 70 W acoustic power. The size of the lesion (ablated zone) was measured at sonication times, 20 s, 30 s and 40 s. Numerical calculations were performed to validate the experimental lesion size. Also, a histology study of the ablated liver sample was performed to confirm cell necrosis within the ablated zones. It was found that the HIFU induced lesion size is strongly dependant on sonication time and lesion size almost doubles (increases from 0.368 to 0.715 cm2) as sonication time increases from 20s to 40s. The area of lesions, determined experimentally, agreed within 5% with results of numerical calculations.

scholarly journals Monitoring Microwave Ablation Using Ultrasound Echo Decorrelation Imaging: An ex vivo Study

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 977 ◽  
Author(s):  
Zhuhuang Zhou ◽  
Yue Wang ◽  
Shuang Song ◽  
Weiwei Wu ◽  
Shuicai Wu ◽  
...  
Keyword(s):  
Polynomial Approximation ◽  
Microwave Ablation ◽  
Ex Vivo ◽  
Porcine Liver ◽  
Thermal Lesion ◽  
Monitoring Method ◽  
Thermal Lesions ◽  
Array Transducer ◽  
Average Accuracy ◽  
Rf Signals

In this study, a microwave-induced ablation zone (thermal lesion) monitoring method based on ultrasound echo decorrelation imaging was proposed. A total of 15 cases of ex vivo porcine liver microwave ablation (MWA) experiments were carried out. Ultrasound radiofrequency (RF) signals at different times during MWA were acquired using a commercial clinical ultrasound scanner with a 7.5-MHz linear-array transducer. Instantaneous and cumulative echo decorrelation images of two adjacent frames of RF data were calculated. Polynomial approximation images were obtained on the basis of the thresholded cumulative echo decorrelation images. Experimental results showed that the instantaneous echo decorrelation images outperformed conventional B-mode images in monitoring microwave-induced thermal lesions. Using gross pathology measurements as the reference standard, the estimation of thermal lesions using the polynomial approximation images yielded an average accuracy of 88.60%. We concluded that instantaneous ultrasound echo decorrelation imaging is capable of monitoring the change of thermal lesions during MWA, and cumulative ultrasound echo decorrelation imaging and polynomial approximation imaging are feasible for quantitatively depicting thermal lesions.

Sign in / Sign up

Export Citation Format

Share Document