The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Elisa Konofagou - One of the best experts on this subject based on the ideXlab platform.
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Feasibility of Harmonic Motion Imaging Using A Single Transducer: In Vivo Imaging of Breast Cancer in A Mouse Model and Human Subjects.
IEEE transactions on medical imaging, 2021Co-Authors: Murad Hossain, Niloufar Saharkhiz, Elisa KonofagouAbstract:Harmonic Motion imaging (HMI) interrogates the mechanical properties of tissues by simultaneously generating and tracking Harmonic oscillation using focused ultrasound and imaging transducers, respectively. Instead of using two transducers, the objective of this work is to develop a single transducer HMI (ST-HMI) to both generate and track Harmonic Motion at "on-axis" to the force for facilitating data acquisition. In ST-HMI, the amplitude-modulated force was generated by modulating excitation pulse duration and tracking of Motion was performed by transmitting tracking pulses interleaved between excitation pulses. The feasibility of ST-HMI was performed by imaging two elastic phantoms with three inclusions (N=6) and comparing it with acoustic radiation force impulse (ARFI) imaging, in vivo longitudinal monitoring of 4T1, orthotropic breast cancer mice (N=4), and patients (N=3) with breast masses in vivo. Six inclusions with Young's moduli of 8, 10, 15, 20, 40, and 60 kPa were embedded in a 5 kPa background. The ST-HMI-derived peak-to-peak displacement (P2PD) successfully detected all inclusions with R2=0.93 of the linear regression between the P2PD ratio of background to inclusion versus Young's moduli ratio of inclusion to background. The contrasts of 10 and 15 kPa inclusions were higher in ST-HMI than ARFI-derived images. In the mouse study, the median P2PD ratio of tumor to non-cancerous tissues was 3.0, 5.1, 6.1, and 7.7 at 1, 2, 3, and 4 weeks post-injection of the tumor cells, respectively. In the clinical study, ST-HMI detected breast masses including fibroadenoma, pseudo angiomatous stromal hyperplasia, and invasive ductal carcinoma with a P2PD ratio of 1.37, 1.61, and 1.78, respectively. These results indicate that ST-HMI can assess the mechanical properties of tissues via generation and tracking of Harmonic Motion "on-axis" to the ARF. This study is the first step towards translating ST-HMI in clinics.
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In Vivo Demonstration of Single Transducer Harmonic Motion Imaging (ST-HMI) in a Breast Cancer Mouse Model and Breast Cancer Patients
2020 IEEE International Ultrasonics Symposium (IUS), 2020Co-Authors: Murad Hossain, Niloufar Saharkhiz, Elisa KonofagouAbstract:Harmonic Motion imaging (HMI) interrogates the mechanical properties of tissues by simultaneously generating and tracking amplitude-modulated (AM) force-induced Motion using focused ultrasound and imaging transducers, respectively. The main advantages of HMI are that Motion at oscillation frequency can be easily filtered from different Motion artifacts. However, the current configuration of two separate transducers renders the HMI system highly complex. The objective of this study is to develop a single transducer HMI (ST-HMI) and test its feasibility of generating and mapping of Harmonic Motion using a linear array transducer to facilitate data acquisition. The feasibility of ST-HMI was performed by imaging commercially available two elastic phantoms with two inclusions (N=4), in vivo monitoring of changes in the tumor stiffness of 4T1, orthotropic breast cancer mouse model, and patient with invasive ductal carcinoma (IDC) breast cancer. ST-HMI-derived peak-to-peak displacements (P2PD) successfully contrasted all 4 inclusions with nominal Young's modulus of 8, 10, 40, and 60 kPa and the P2PD ratio of background to inclusion was highly correlated with Young's modulus ratio of inclusion to background with R2 of 0.93. In the mouse study, the median P2PD ratio of the tumor to non-cancerous tissue was 2.0, 3.6, 7.0, and 6.6 at 1, 2, 3, and 4 weeks, respectively, post-injection of the tumor cell. In the clinical study, ST-HMI detected IDC cancer with the P2PD ratio of 1.78. These results indicate that ST-HMI can assess the mechanical properties of tissues via generation and tracking of Harmonic Motion using a single transducer.
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Frequency dependence of inclusion characterization in Harmonic Motion imaging
2020 IEEE International Ultrasonics Symposium (IUS), 2020Co-Authors: Niloufar Saharkhiz, Hermes A. S. Kamimura, Murad Hossain, Elisa KonofagouAbstract:Harmonic Motion imaging (HMI) is an elasticity imaging method that employs an amplitude modulated (AM) acoustic radiation force to generate oscillations within the tissue. Recently, the capability of HMI in characterizing tumors with different geometries and pathologies was demonstrated in murine and human subjects using an AM frequency of 25 Hz. However, there is still a need to optimize the technique to reconstruct small lesions and improve image contrast. In this study, we investigated the role of the AM frequency in HMI and how it can detect and characterize inclusions with different sizes and stiffnesses in experimental tissue-mimicking phantoms.
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Focused Ultrasound Steering for Harmonic Motion Imaging
IEEE transactions on ultrasonics ferroelectrics and frequency control, 2018Co-Authors: Yang Han, Shutao Wang, Thomas Payen, Elisa KonofagouAbstract:Harmonic Motion imaging (HMI) is a radiation-force-based ultrasound elasticity imaging technique, which is designed for both tissue relative stiffness imaging and reliable high-intensity focused ultrasound treatment monitoring. The objective of this letter is to develop and demonstrate the feasibility of 2-D focused ultrasound (FUS) beam steering for HMI using a 93-element, FUS phased array. HMI with steered FUS beam was acquired in tissue-mimicking phantoms. The HMI displacement was imaged within the steering range of ±1.7 mm laterally and ±2 mm axially. Using the steered FUS beam, HMI can be used to image a larger tissue volume with higher efficiency and without requiring mechanical movement of the transducer.
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fast lesion mapping during hifu treatment using Harmonic Motion imaging guided focused ultrasound hmigfus in vitro and in vivo
Physics in Medicine and Biology, 2017Co-Authors: Yang Han, Shutao Wang, Thomas Payen, Elisa KonofagouAbstract:The successful clinical application of high intensity focused ultrasound (HIFU) ablation depends on reliable monitoring of the lesion formation. Harmonic Motion imaging guided focused ultrasound (HMIgFUS) is an ultrasound-based elasticity imaging technique, which monitors HIFU ablation based on the stiffness change of the tissue instead of the echo intensity change in conventional B-mode monitoring, rendering it potentially more sensitive to lesion development. Our group has shown that predicting the lesion location based on the radiation force-excited region is feasible during HMIgFUS. In this study, the feasibility of a fast lesion mapping method is explored to directly monitor the lesion map during HIFU. The Harmonic Motion imaging (HMI) lesion map was generated by subtracting the reference HMI image from the present HMI peak-to-peak displacement map, as streamed on the computer display. The dimensions of the HMIgFUS lesions were compared against gross pathology. Excellent agreement was found between the lesion depth (r 2 = 0.81, slope = 0.90), width (r 2 = 0.85, slope = 1.12) and area (r 2 = 0.58, slope = 0.75). In vivo feasibility was assessed in a mouse with a pancreatic tumor. These findings demonstrate that HMIgFUS can successfully map thermal lesions and monitor lesion development in real time in vitro and in vivo. The HMIgFUS technique may therefore constitute a novel clinical tool for HIFU treatment monitoring.
Kullervo Hynynen - One of the best experts on this subject based on the ideXlab platform.
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In vivo localized Harmonic Motion imaging of VX2 tumors
2012Co-Authors: Laura Curiel, Kullervo HynynenAbstract:We evaluated the feasibility of localized Harmonic Motion (LHM) imaging for tumor detection in vivo. LHM was induced using a single-element focused ultrasound (FUS) transducer (80 mm focal, 100 mm diameter, 1.54 MHz) and a separate transducer (5 kHz PRF, 5 MHz) was used to track Motion by cross-correlating RF signals. A scan was performed with the transducers assembly and LHM was induced 5 times per location. Images were formed averaging the calculated LHM amplitudes. Ten New Zealand rabbits had VX2 tumors implanted on their thighs. Tumors were located using Magnetic resonance images and LHM images were obtained. Eight out of ten tumors were visualized on LHM images as a region with lower amplitude (5.7±1.3μm in tumors and 19.5±5.8μm in muscle). All tumors had an elongated shape running along the muscle fibers. It was possible to detect tumors larger than 4mm in width (short axis of the tumor). We performed a FUS ablation of one tumor and the ablated region was detected as well on LHM images as a reduced ...
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Localized Harmonic Motion imaging for focused ultrasound surgery targeting.
Ultrasound in medicine & biology, 2011Co-Authors: Laura Curiel, Kullervo HynynenAbstract:Recently, an in vivo real-time ultrasound-based monitoring technique that uses localized Harmonic Motion (LHM) to detect changes in tissues during focused ultrasound surgery (FUS) has been proposed to control the exposure. This technique can potentially be used as well for targeting imaging. In the present study, we evaluated the potential of using LHM to detect changes in stiffness and the feasibility of using it for imaging purposes in phantoms and in vivo tumor detection. A single-element FUS transducer (80 mm focal length, 100 mm diameter, 1.485 MHz) was used for inducing a localized Harmonic Motion and a separate ultrasound diagnostic transducer excited by a pulser/receiver (5 kHz PRF, 5 MHz) was used to track Motion. The Motion was estimated using cross-correlation techniques on the acquired radio-frequency (RF) signal. Silicon phantom studies were performed to determine the size of inclusion that was possible to detect using this technique. Inclusions were discerned from the surroundings as a reduction on LHM amplitude and it was possible to depict inclusions as small as 4 mm. The amplitude of the induced LHM was always lower at the inclusions compared with the one obtained at the surroundings. Ten New Zealand rabbits had VX2 tumors implanted on their thighs and LHM was induced and measured at the tumor region. Tumors (as small as 10 mm in length and 4 mm in width) were discerned from the surroundings as a reduction on LHM amplitude.
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Localized Harmonic Motion imaging for Focused Ultrasound Surgery targeting and treatment outcome
2010 IEEE International Ultrasonics Symposium, 2010Co-Authors: Laura Curiel, Kullervo HynynenAbstract:Focused Ultrasound Surgery (FUS) has been proposed as a noninvasive thermal therapy for diverse applications. FUS can generate a well-localized and fast rise of temperate that induces tissue coagulation. Recently, an in vivo real-time ultrasound-based monitoring technique that uses localized Harmonic Motion (LHM) to detect changes in tissues during FUS has been proposed to control the coagulation. This technique can potentially be used for targeting and post-treatment imaging. This will provide for an alternative imaging method to Magnetic Resonance Imaging which is currently the FDA-approved method for FUS treatment targeting and control. In the present study, we evaluated the feasibility of using LHM to detect changes in tissues stiffness and use it for FUS therapy targeting and follow up. A single-element FUS transducer (80-mm focal length, 100-mm diameter, 1.485 MHz) was used for inducing a localized Harmonic Motion. A separate ultrasound diagnostic transducer (5 MHz) was used to track tissue Motion and the Motion was estimated using cross-correlation techniques. Silicon phantom studies were performed in order to determine the hardness difference and size of inclusion that was possible to detect. On these phantoms, it was possible to detect inclusions as small as 4 mm. Seven New Zealand rabbits had VX2 tumors implanted on their thighs and LHM was induced and measured at the tumor region before and after FUS was carried out. LHM amplitude registered after FUS decreased all times and it was possible to detect lesions. Tumors were discerned from the surroundings as a reduction on LHM amplitude as compared to the surroundings. The sensitivity was low as well when small tumors were imaged.
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Local Harmonic Motion Monitoring of Focused Ultrasound Surgery—A Simulation Model
IEEE transactions on bio-medical engineering, 2009Co-Authors: J. Heikkila, Laura Curiel, Kullervo HynynenAbstract:In this paper, a computational model for localized Harmonic Motion (LHM) imaging-based monitoring of high-intensity focused ultrasound surgery (FUS) is presented. The LHM technique is based on a focused, time-varying ultrasound radiation force excitation, which induces local oscillatory Motions at the focal region. These vibrations are tracked, using pulse-echo imaging, and then, used to estimate the mechanical properties of the sonication region. LHM is feasible for FUS monitoring because changes in the material properties during the coagulation process affect the measured displacements. The presented model includes separate models to simulate acoustic sonication fields, sonication-induced temperature elevation and mechanical Motion, and pulse-echo imaging of the induced Motions. These 3-D simulation models are based on Rayleigh-Sommerfield integral, finite element, and spatial impulse response methods. Simulated-tissue temperature elevation and mechanical Motion were compared with previously published in vivo measurements. Finally, the simulation model was used to simulate coagulation and LHM monitoring, as would occur with multiple, neighbouring sonication locations covering a large tumor.
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A Simulation Model for Local Harmonic Motion Monitoring of Focused Ultrasound Surgery
2009Co-Authors: Janne Heikkilä, Laura Curiel, Kullervo HynynenAbstract:A computational model for local Harmonic Motion (LHM) imaging‐based monitoring of high‐intensity focused ultrasound surgery (FUS) is presented. LMH technique is based on a focused ultrasound radiation force excitation, which induces local mechanical vibrations at the focal region. These pulse‐echo imaged vibrations are then used to estimate the mechanical properties of the sonication region. LHM has been proven to be feasible for FUS monitoring because changes in the material properties during the coagulation affect the measured displacements. The presented model includes separate models to simulate acoustic fields, sonication induced temperature elevation and mechanical vibrations, and pulse‐echo imaging of the induced Motions. These simulation models are based on Rayleigh integral, finite element, and spatial impulse response methods. Simulated temperature rise and vibration amplitudes have been compared with in vivo rabbit experiments with noninvasive MRI thermometry.
Yang Han - One of the best experts on this subject based on the ideXlab platform.
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Focused Ultrasound Steering for Harmonic Motion Imaging
IEEE transactions on ultrasonics ferroelectrics and frequency control, 2018Co-Authors: Yang Han, Shutao Wang, Thomas Payen, Elisa KonofagouAbstract:Harmonic Motion imaging (HMI) is a radiation-force-based ultrasound elasticity imaging technique, which is designed for both tissue relative stiffness imaging and reliable high-intensity focused ultrasound treatment monitoring. The objective of this letter is to develop and demonstrate the feasibility of 2-D focused ultrasound (FUS) beam steering for HMI using a 93-element, FUS phased array. HMI with steered FUS beam was acquired in tissue-mimicking phantoms. The HMI displacement was imaged within the steering range of ±1.7 mm laterally and ±2 mm axially. Using the steered FUS beam, HMI can be used to image a larger tissue volume with higher efficiency and without requiring mechanical movement of the transducer.
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fast lesion mapping during hifu treatment using Harmonic Motion imaging guided focused ultrasound hmigfus in vitro and in vivo
Physics in Medicine and Biology, 2017Co-Authors: Yang Han, Shutao Wang, Thomas Payen, Elisa KonofagouAbstract:The successful clinical application of high intensity focused ultrasound (HIFU) ablation depends on reliable monitoring of the lesion formation. Harmonic Motion imaging guided focused ultrasound (HMIgFUS) is an ultrasound-based elasticity imaging technique, which monitors HIFU ablation based on the stiffness change of the tissue instead of the echo intensity change in conventional B-mode monitoring, rendering it potentially more sensitive to lesion development. Our group has shown that predicting the lesion location based on the radiation force-excited region is feasible during HMIgFUS. In this study, the feasibility of a fast lesion mapping method is explored to directly monitor the lesion map during HIFU. The Harmonic Motion imaging (HMI) lesion map was generated by subtracting the reference HMI image from the present HMI peak-to-peak displacement map, as streamed on the computer display. The dimensions of the HMIgFUS lesions were compared against gross pathology. Excellent agreement was found between the lesion depth (r 2 = 0.81, slope = 0.90), width (r 2 = 0.85, slope = 1.12) and area (r 2 = 0.58, slope = 0.75). In vivo feasibility was assessed in a mouse with a pancreatic tumor. These findings demonstrate that HMIgFUS can successfully map thermal lesions and monitor lesion development in real time in vitro and in vivo. The HMIgFUS technique may therefore constitute a novel clinical tool for HIFU treatment monitoring.
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Tumor characterization and treatment monitoring of postsurgical human breast specimens using Harmonic Motion imaging (HMI)
Breast Cancer Research, 2016Co-Authors: Yang Han, Shutao Wang, Bret Taback, Hanina Hibshoosh, Elisa KonofagouAbstract:BackgroundHigh-intensity focused ultrasound (HIFU) is a noninvasive technique used in the treatment of early-stage breast cancer and benign tumors. To facilitate its translation to the clinic, there is a need for a simple, cost-effective device that can reliably monitor HIFU treatment. We have developed Harmonic Motion imaging (HMI), which can be used seamlessly in conjunction with HIFU for tumor ablation monitoring, namely Harmonic Motion imaging for focused ultrasound (HMIFU). The overall objective of this study was to develop an all ultrasound-based system for real-time imaging and ablation monitoring in the human breast in vivo.MethodsHMI was performed in 36 specimens (19 normal, 15 invasive ductal carcinomas, and 2 fibroadenomas) immediately after surgical removal. The specimens were securely embedded in a tissue-mimicking agar gel matrix and submerged in degassed phosphate-buffered saline to mimic in vivo environment. The HMI setup consisted of a HIFU transducer confocally aligned with an imaging transducer to induce an oscillatory radiation force and estimate the resulting displacement.Results3D HMI displacement maps were reconstructed to represent the relative tissue stiffness in 3D. The average peak-to-peak displacement was found to be significantly different ( p = 0.003) between normal breast tissue and invasive ductal carcinoma. There were also significant differences before and after HMIFU ablation in both the normal (53.84 % decrease) and invasive ductal carcinoma (44.69 % decrease) specimens.ConclusionsHMI can be used to map and differentiate relative stiffness in postsurgical normal and pathological breast tissues. HMIFU can also successfully monitor thermal ablations in normal and pathological human breast specimens. This HMI technique may lead to a new clinical tool for breast tumor imaging and HIFU treatment monitoring.
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tumor characterization and treatment monitoring of postsurgical human breast specimens using Harmonic Motion imaging hmi
Breast Cancer Research, 2016Co-Authors: Yang Han, Shutao Wang, Bret Taback, Hanina Hibshoosh, Elisa KonofagouAbstract:High-intensity focused ultrasound (HIFU) is a noninvasive technique used in the treatment of early-stage breast cancer and benign tumors. To facilitate its translation to the clinic, there is a need for a simple, cost-effective device that can reliably monitor HIFU treatment. We have developed Harmonic Motion imaging (HMI), which can be used seamlessly in conjunction with HIFU for tumor ablation monitoring, namely Harmonic Motion imaging for focused ultrasound (HMIFU). The overall objective of this study was to develop an all ultrasound-based system for real-time imaging and ablation monitoring in the human breast in vivo. HMI was performed in 36 specimens (19 normal, 15 invasive ductal carcinomas, and 2 fibroadenomas) immediately after surgical removal. The specimens were securely embedded in a tissue-mimicking agar gel matrix and submerged in degassed phosphate-buffered saline to mimic in vivo environment. The HMI setup consisted of a HIFU transducer confocally aligned with an imaging transducer to induce an oscillatory radiation force and estimate the resulting displacement. 3D HMI displacement maps were reconstructed to represent the relative tissue stiffness in 3D. The average peak-to-peak displacement was found to be significantly different (p = 0.003) between normal breast tissue and invasive ductal carcinoma. There were also significant differences before and after HMIFU ablation in both the normal (53.84 % decrease) and invasive ductal carcinoma (44.69 % decrease) specimens. HMI can be used to map and differentiate relative stiffness in postsurgical normal and pathological breast tissues. HMIFU can also successfully monitor thermal ablations in normal and pathological human breast specimens. This HMI technique may lead to a new clinical tool for breast tumor imaging and HIFU treatment monitoring.
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Harmonic Motion imaging for pancreatic tumor detection and high-intensity focused ultrasound ablation monitoring
Journal of therapeutic ultrasound, 2015Co-Authors: Hong Chen, Yang Han, Thomas Payen, Carmine F. Palermo, Kenneth P. Olive, Elisa KonofagouAbstract:Harmonic Motion imaging (HMI) is a radiation force-based elasticity imaging technique that estimates tissue Harmonic displacements induced by an oscillatory ultrasonic radiation force to assess tissue stiffness. The objective of this study was to evaluate the feasibility of applying HMI on pancreatic tumor detection and high-intensity focused ultrasound (HIFU) treatment monitoring.
Laura Curiel - One of the best experts on this subject based on the ideXlab platform.
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In vivo localized Harmonic Motion imaging of VX2 tumors
2012Co-Authors: Laura Curiel, Kullervo HynynenAbstract:We evaluated the feasibility of localized Harmonic Motion (LHM) imaging for tumor detection in vivo. LHM was induced using a single-element focused ultrasound (FUS) transducer (80 mm focal, 100 mm diameter, 1.54 MHz) and a separate transducer (5 kHz PRF, 5 MHz) was used to track Motion by cross-correlating RF signals. A scan was performed with the transducers assembly and LHM was induced 5 times per location. Images were formed averaging the calculated LHM amplitudes. Ten New Zealand rabbits had VX2 tumors implanted on their thighs. Tumors were located using Magnetic resonance images and LHM images were obtained. Eight out of ten tumors were visualized on LHM images as a region with lower amplitude (5.7±1.3μm in tumors and 19.5±5.8μm in muscle). All tumors had an elongated shape running along the muscle fibers. It was possible to detect tumors larger than 4mm in width (short axis of the tumor). We performed a FUS ablation of one tumor and the ablated region was detected as well on LHM images as a reduced ...
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Localized Harmonic Motion imaging for focused ultrasound surgery targeting.
Ultrasound in medicine & biology, 2011Co-Authors: Laura Curiel, Kullervo HynynenAbstract:Recently, an in vivo real-time ultrasound-based monitoring technique that uses localized Harmonic Motion (LHM) to detect changes in tissues during focused ultrasound surgery (FUS) has been proposed to control the exposure. This technique can potentially be used as well for targeting imaging. In the present study, we evaluated the potential of using LHM to detect changes in stiffness and the feasibility of using it for imaging purposes in phantoms and in vivo tumor detection. A single-element FUS transducer (80 mm focal length, 100 mm diameter, 1.485 MHz) was used for inducing a localized Harmonic Motion and a separate ultrasound diagnostic transducer excited by a pulser/receiver (5 kHz PRF, 5 MHz) was used to track Motion. The Motion was estimated using cross-correlation techniques on the acquired radio-frequency (RF) signal. Silicon phantom studies were performed to determine the size of inclusion that was possible to detect using this technique. Inclusions were discerned from the surroundings as a reduction on LHM amplitude and it was possible to depict inclusions as small as 4 mm. The amplitude of the induced LHM was always lower at the inclusions compared with the one obtained at the surroundings. Ten New Zealand rabbits had VX2 tumors implanted on their thighs and LHM was induced and measured at the tumor region. Tumors (as small as 10 mm in length and 4 mm in width) were discerned from the surroundings as a reduction on LHM amplitude.
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Localized Harmonic Motion imaging for Focused Ultrasound Surgery targeting and treatment outcome
2010 IEEE International Ultrasonics Symposium, 2010Co-Authors: Laura Curiel, Kullervo HynynenAbstract:Focused Ultrasound Surgery (FUS) has been proposed as a noninvasive thermal therapy for diverse applications. FUS can generate a well-localized and fast rise of temperate that induces tissue coagulation. Recently, an in vivo real-time ultrasound-based monitoring technique that uses localized Harmonic Motion (LHM) to detect changes in tissues during FUS has been proposed to control the coagulation. This technique can potentially be used for targeting and post-treatment imaging. This will provide for an alternative imaging method to Magnetic Resonance Imaging which is currently the FDA-approved method for FUS treatment targeting and control. In the present study, we evaluated the feasibility of using LHM to detect changes in tissues stiffness and use it for FUS therapy targeting and follow up. A single-element FUS transducer (80-mm focal length, 100-mm diameter, 1.485 MHz) was used for inducing a localized Harmonic Motion. A separate ultrasound diagnostic transducer (5 MHz) was used to track tissue Motion and the Motion was estimated using cross-correlation techniques. Silicon phantom studies were performed in order to determine the hardness difference and size of inclusion that was possible to detect. On these phantoms, it was possible to detect inclusions as small as 4 mm. Seven New Zealand rabbits had VX2 tumors implanted on their thighs and LHM was induced and measured at the tumor region before and after FUS was carried out. LHM amplitude registered after FUS decreased all times and it was possible to detect lesions. Tumors were discerned from the surroundings as a reduction on LHM amplitude as compared to the surroundings. The sensitivity was low as well when small tumors were imaged.
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Local Harmonic Motion Monitoring of Focused Ultrasound Surgery—A Simulation Model
IEEE transactions on bio-medical engineering, 2009Co-Authors: J. Heikkila, Laura Curiel, Kullervo HynynenAbstract:In this paper, a computational model for localized Harmonic Motion (LHM) imaging-based monitoring of high-intensity focused ultrasound surgery (FUS) is presented. The LHM technique is based on a focused, time-varying ultrasound radiation force excitation, which induces local oscillatory Motions at the focal region. These vibrations are tracked, using pulse-echo imaging, and then, used to estimate the mechanical properties of the sonication region. LHM is feasible for FUS monitoring because changes in the material properties during the coagulation process affect the measured displacements. The presented model includes separate models to simulate acoustic sonication fields, sonication-induced temperature elevation and mechanical Motion, and pulse-echo imaging of the induced Motions. These 3-D simulation models are based on Rayleigh-Sommerfield integral, finite element, and spatial impulse response methods. Simulated-tissue temperature elevation and mechanical Motion were compared with previously published in vivo measurements. Finally, the simulation model was used to simulate coagulation and LHM monitoring, as would occur with multiple, neighbouring sonication locations covering a large tumor.
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IN VIVO MONITORING OF FOCUSED ULTRASOUND SURGERY USING LOCAL Harmonic Motion
Ultrasound in medicine & biology, 2008Co-Authors: Laura Curiel, Rajiv Chopra, Kullervo HynynenAbstract:The present study established the feasibility of a technique for monitoring FUS lesion formation in vivo using localized Harmonic Motion (LHM) measurements. Oscillatory Motion (frequencies between 50 and 300 Hz) was generated within tissues by induction of a periodic radiation force with a focused ultrasound (FUS) transducer. The Harmonic Motion was estimated using cross-correlation of RF ultrasonic signals acquired at different instances during the Motion by using a confocal diagnostic ultrasound transducer. The technique was evaluated in vivo in rabbit muscle (14 locations) in an MR imager for simultaneous ultrasound Harmonic Motion tracking and MR thermometry. The measured maximum amplitude of the induced Harmonic Motion before and after the lesion formation was significantly different for all the tested Motion frequencies and decreased between 17 and 81% depending on the frequency and location. During the FUS exposure a drop in the maximum amplitude value was observed and a threshold value could be associated to the formation of a thermal lesion. A series of controlled sonications was performed by stopping the exposure when the threshold value in LHM amplitude was reached and the presence of a thermal lesion was confirmed by MR imaging. LHM measurements were also used to perform a spatial scan of the tissues across the exposure region and the thermal lesions could be detected as a reduction in the maximum Motion amplitude value at the sonication region.
Nevzat G. Gencer - One of the best experts on this subject based on the ideXlab platform.
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An Improved Receiver for Harmonic Motion Microwave Doppler Imaging
2020 14th European Conference on Antennas and Propagation (EuCAP), 2020Co-Authors: Damla Alptekin Soydan, Umit Irgin, Can Baris Top, Nevzat G. GencerAbstract:Harmonic Motion microwave Doppler imaging is a novel imaging modality that combines focused ultrasound and radar techniques to obtain data based on mechanical and electrical properties of the tissue. In previous experimental studies, the Doppler component of the scattered signal is sensed and used to create 2D images of a tumor inside a homogeneous fat phantom. Due to the drawbacks of the receiver configuration, scanning time was high, the signal-to-noise ratio was low, and the multi-frequency operation was limited. In this study, we improved the receiving system with a low noise amplifier which led to an increase in signal-to-noise ratio and a decrease in data acquisition time. A breast phantom containing a cylindrical tumor of size 3 mm $\times 3$ mm inside a homogeneous fat was built to perform 2D scans. An area of 40 mm $\times 40$ mm is scanned in 45 minutes which is approximately 50% of the previous scanning time. Multiple vibration frequencies between 15 Hz - 60 Hz are used to create 2D images. With the enhancement of the signal-to-noise ratio, vibration frequencies higher than 35 Hz are used for the first time. Increase in the vibration frequency resulted in the improvement of resolution; however, signal-to-noise ratio deteriorated due to the decrease in the vibration amplitude.
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ISMICT - Received signal in Harmonic Motion microwave doppler imaging as a function of tumor position in a 3D scheme
2017 11th International Symposium on Medical Information and Communication Technology (ISMICT), 2017Co-Authors: Umit Irgin, Azadeh Kamali Tafreshi, Can Baris Top, Nevzat G. GencerAbstract:Harmonic Motion Microwave Doppler Imaging method, which was proposed as an alternative method for breast tumor detection, is a combination of microwave radar and focused ultrasound techniques yielding data depending on electrical and mechanical properties of the tissue. In this study, Harmonic Motion Microwave Doppler Imaging data from a small tumor inside homogeneous fat is analyzed as a function of tumor location on three orthogonal planes using Finite Difference Time Domain simulations. The results show that the resolution on the order of millimeters is achievable with this method.
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Microwave Sensing of Acoustically Induced Local Harmonic Motion: Experimental and Simulation Studies on Breast Tumor Detection
IEEE Transactions on Microwave Theory and Techniques, 2016Co-Authors: Can Baris Top, Azadeh Kamali Tafreshi, Nevzat G. GencerAbstract:Sensing acoustically induced local Harmonic Motion using a microwave transceiver system may provide useful information for detecting nonpalpable tumors in dense breast tissue. For this purpose, we propose the Harmonic Motion microwave Doppler imaging method, in which the first Harmonic of the phase modulated signal due to local Harmonic Motion is sensed. This signal is related to the dielectric, elastic, and acoustic properties of the vibrating region. The purpose of this paper is twofold: 1) to demonstrate the concept of this method with experiments using phantom materials mimicking the elastic and electrical properties of the breast tissue and 2) to investigate the effect of fibroglandular region size and vibration frequency on the received signal, using numerical simulations. A breast phantom with a tumor phantom inclusion (5-mm diameter and 7-mm height) inside fibroglandular region is constructed for the experimental study. The response due to a focused ultrasound probe is linearly scanned at 30-mm depth from the phantom surface, and the Doppler signal level is tracked using a spectrum analyzer. It is shown that the tumor phantom is resolvable inside the surrounding fibroglandular region with about a 3–5-dB decrease in the signal level. The simulations, using the finite-difference time-domain method, show that the received signal level depends on the relative size of the fibroglandular region with respect to the vibrating region size. Further experimental and numerical studies are needed to investigate the feasibility of this method and to optimize the imaging system design.
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EMBC - Harmonic Motion Microwave Doppler Imaging method for breast tumor detection.
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Inte, 2014Co-Authors: Can Barisc Top, Azadeh Kamali Tafreshi, Nevzat G. GencerAbstract:Harmonic Motion Microwave Doppler Imaging (HMMDI) method is recently proposed as a non-invasive hybrid breast imaging technique for tumor detection. The acquired data depend on acoustic, elastic and electromagnetic properties of the tissue. The potential of the method is analyzed with simulation studies and phantom experiments. In this paper, the results of these studies are summarized. It is shown that HMMDI method has a potential to detect malignancies inside fibro-glandular tissue.
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EMBC - Data acquisition system for Harmonic Motion microwave Doppler imaging.
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Inte, 2014Co-Authors: Azadeh Kamali Tafreshi, Mürsel Karadas, Can Bans Top, Nevzat G. GencerAbstract:Harmonic Motion Microwave Doppler Imaging (HMMDI) is a hybrid method proposed for breast tumor detection, which images the coupled dielectric and elastic properties of the tissue. In this paper, the performance of a data acquisition system for HMMDI method is evaluated on breast phantom materials. A breast fat phantom including fibro-glandular and tumor phantom regions is produced. The phantom is excited using a focused ultrasound probe and a microwave transmitter. The received microwave signal level is measured on three different points inside the phantom (fat, fibro-glandular, and tumor regions). The experimental results using the designed homodyne receiver proved the effectiveness of the proposed setup. In tumor phantom region, the signal level decreased about 3 dB compared to the signal level obtained from the fibro-glandular phantom area, whereas this signal was about 4 dB higher than the received signal from the fat phantom.
