2010 IEEE International Ultrasonics Symposium最新文献

{"title":"Simple method for measuring phase transfer functions of transducers","authors":"P. van Neer, H. Vos, M. Danilouchkine, N. de Jong","doi":"10.1109/ULTSYM.2010.5935890","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935890","url":null,"abstract":"The impulse response of a transducer can be represented in the frequency domain by its complex analog, the transfer function. The amplitude transfer function is measured regularly in contrast to the phase transfer function (PTF). Applications for the PTF range from adjusting the emitted pulse shape for coding based imaging to the optimization of ultrasound contrast imaging methods based on destructive interference. A number of acoustic methods to measure a transducer's PTF exists, but they usually require accurate distance and acoustic wave speed measurements. Small discrepancies in these cause large phase errors. We present a pulse-echo method to measure a transducer's PTF without needing a measurement of the wave travel distance and speed. We generalize it to rectangular transducers. In our method the transducer is excited by a monofrequency sine burst with a rectangular envelope. The transducer initially vibrates at resonance (transient regime) prior to the forcing frequency (steady state regime). The PTF value of the system is the difference between the phases deduced from the transient and the steady state regimes at different forcing frequencies. As the PTF is calculated from a relative difference measuring the wave travel distance or speed is unnecessary. The approach assumes linear wave propagation and uses a pulse-echo setup. The method was tested on a custom built single element transducer (square: 13 × 13 mm, center frequency 4 MHz, no backing or matching layers). The results were compared with KLM model simulations. Also, we phase calibrated a hydrophone, which was then used to measure the PTF of the square transducer. The simulated and measured resonance frequencies differed by 0.17 MHz. The mean PTF difference between simulation and measurements was 7°–14°. The method's reproducibility was ±15°. The PTF of the transducer was measured with good reproducibility, without measuring the wave travel distance or speed of sound in the medium. Our simple setup requires basic laboratory ultrasound equipment.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84628166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the effects of flow acceleration on blood aggregation by high frequency duplex ultrasound: Under pulsatile flow","authors":"Yu-Chang Chang, Po-Yang Lee, Chen-Chih Liao, Chih-Chung Huang","doi":"10.1109/ULTSYM.2010.5935884","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935884","url":null,"abstract":"The echogenicity of whole blood is known to vary during the flow cycle under pulsatile flow both in vitro and in vivo. However, the fundamental underlying mechanisms remain uncertain. The cyclic variations of high frequency ultrasonic backscattering signals have been measured for explaining the temporal variations of red blood cells (RBCs) aggregation under pulsatile flow. The level of RBC aggregation was enhanced by reducing the flow velocity. However, the size of rouleau still increased during the flow acceleration phase. This observation is opposite to previous studies which the formation of rouleau should be broke up by increasing the shear force of flow. In order to further explore this phenomenon, the effect of flow acceleration on RBC aggregation was studied by high frequency duplex ultrasound. The experiments were performed on porcine whole blood with different hematocrits from 20 to 40%. The blood was circulated in a pulsatile Couette flow apparatus under different flow accelerations. Both ultrasound M-mode images and Doppler flow information from flowing blood were obtained by the 35 MHz and 30 MHz transducers, respectively. The backscattering signals and Doppler flow velocities were acquired synchronously to compare the relationship between flow acceleration and blood aggregation. The results indicated that the cyclic variations became weaker as the stroke rate increased and the variation was higher for a hematocrit of 40% than for one of 20%. However, the cyclic variation became stronger with increase of peak flow velocity. The flow velocity between 10 to 20 cm/s can be treated as a threshold for rouleaux disaggregation under pulsatile flow during the acceleration phase.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81402443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In vivo assessment of inflammatory skin using high frequency ultrasound image and quantitative parameters","authors":"Yi-Hsun Lin, Chih-Chung Huang, Shyh-Hau Wang","doi":"10.1109/ULTSYM.2010.5935602","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935602","url":null,"abstract":"Histological examination remains the most direct means to assess the inflammatory tissue. It however is still with the nature of invasiveness and is time consuming for the preparation of tissue slices. The slice apparently is not applicable for a long term observation of the tissue in situ. For these reasons, this study is to explore another approach to assess the inflammatory skin using strengths and statistical parameters of high frequency ultrasonic backscattering signals. The experiments were performed from the dorsal skins of BALB/c mice using a 50 MHz ultrasound. The dorsal skins of different mice were injected with a 0.15 ml of either saline or lipopolysaccharides (LPS) with dosage of 2 mg/ml to be as the control group or to induce the local inflammation of the skin as the experiment group, respectively. Each set of experiments was arranged for four days, in which images and backscattered signals of the skins from both control and experiment groups were scanned and acquired daily. Parameters to assess the inflammation included a typical cutaneous thickness estimated from ultrasonic image and that those of integrated backscatter (IB) and Nakagami parameter (m) were calculated from regions of acquired backscattering signals. Results showed that there were no significant differences among measurements of those control groups injected with saline. On the other hand, the inflammatory skin induced by LPS injection tended to result an increase of cutaneous thickness from 0.38±0.07 mm of normal skin to 0.7±0.11 mm of the fourth day. The corresponding IB tended to decrease from −182.5±2.7 dB to −194.4±2.5 dB and m increase slightly from 0.36±0.08 to 0.51±0.12. Those thickness and quantitative parameters variations could be directly associated with changes of tissue properties due to a transfer of massive fluid shifts from the intravascular space into the interstitium and intracellular spaces in the inflammatory skin. This study has demonstrated that cutaneous thickness, integrated backscatter, and Nakagami parameter estimated from high frequency ultrasonic signals are able to be applied to sensitively and quantitatively assess the inflammation of skin.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82576459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automatic 3D left ventricular border detection using active appearance models","authors":"K. Leung, M. van Stralen, G. van Burken, A. V. D. van der Steen, N. de Jong, J. Bosch","doi":"10.1109/ULTSYM.2010.5935446","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935446","url":null,"abstract":"A fully automated segmentation for 3D echocardiography (3DE) using 3D Active Appearance Models (AAM) was developed and evaluated on end-diastolic (ED) and end-systolic (ES) images of 99 patients. The method used ultrasound specific grey value normalization and employed both regular matching and jacobian tuning. The 3D AAM detected the endocardial contours accurately, even in the presence of large variations in left ventricular appearance and shape. Matching was successful in 87% of patients and resulted in good median point-to-surface errors of 2.65 mm for ED and 3.21 for ES, and good volume regressions (ED: y = −3.2 +1.01×, r=0.95; ES: y = −4.6 +1.01×, r=0.92). Results show that fully automated AAM analysis is practically feasible in 3DE datasets of mixed origin and quality.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90398097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study of phased array transducer topology for superharmonic imaging","authors":"P. van Neer, G. Matte, M. Danilouchkine, M. Verweij, N. de Jong","doi":"10.1109/ULTSYM.2010.5935889","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935889","url":null,"abstract":"Since its introduction in the 90s, tissue 2nd harmonic imaging has become the standard in medical ultrasound. Recently, superharmonic imaging (SHI) was introduced. It targets the combination of the 3rd till 5th harmonics. SHI offers increased spatial resolution, lower sidelobes and less artifacts compared to 2nd harmonic imaging. However, a system for SHI has to deal with the lower energy content of the higher harmonics. The broad bandwidth (−6 dB > 130%) required for SHI prompts for an unconventional phased array design. One of the solutions divides the transmit and receive parts into separate acoustic stacks. Such a design reduces the surface area available for reception. Firstly, we investigate the blockwise and interleaved distribution (topology) of the transmit and receive elements in terms of beam characteristics. Secondly, we research the optimal ratio between transmit and receive elements to increase the area dedicated to receiving while retaining a high quality beam. The latter was assessed using the grating lobe to main beam ratio. The acoustic fields were computed using a combination of numerical methods. FIELD II was used to determine the locations and the peak pressure in the fundamental main and grating lobes. The pressure levels of the harmonics in the main and grating lobes were calculated using the INCS method and Burger's equation, respectively. 3 cycle Gaussian apodized sine bursts were used in transmission. The MI was 1.5 at the transmit frequency of 1.2 MHz — optimal for cardiac SHI. The interleaved topology produces the best defined beam (straight and with low sidelobe levels) compared to the blockwise topologies. Consequently, the main to grating lobe ratios for the different harmonic components were calculated for the interleaved topologies only. The 1/2 till 1/7 interleaved topologies provided enough dynamic range (40 dB) for SHI with 1/7 maximizing the surface area for reception. This increases the SNR by 5 dB.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89888348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation for the distribution of fouling deposition on the microfiltration membrane using high frequency ultrasound","authors":"Yi-Hsun Lin, Shyh-Hau Wang, Chih-Chung Huang, Hao-Chuan Pai, K. Tung","doi":"10.1109/ULTSYM.2010.5935712","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935712","url":null,"abstract":"Distribution of fouling may largely affect flux of the microfiltration membrane, in which its formation is related to several factors such as operating pressure, flow rate, concentration/composition of feed solution, and membrane material. It therefore is essential to evaluate fouling distribution on microfiltration membranes before they will be further applied. In this study, an attempt was explored to develop methods and techniques for measuring the fouling distribution using a 35 MHz high frequency ultrasound system. The experiments were carried out from a waste water treatment system that is composed of polyvinylidene fluoride (PVDF) membrane with nominal pore size of 0.22 μm and feed solutions with the humic acid solution of 4 ppm. The operating pressure and flow rate were respectively maintained at 1 bar and 0.22 L/min. Areas of those filtration membranes after 5, 15, 30, 60, and 100 minutes filtration durations were raster scanned by the high frequency ultrasound system. The peak-to-peak voltage (Vpp) of ultrasonic signals reflected from the surface of membrane was calculated for the reconstruction of C-scan images. The average Vpp and flux of filtrate were found to decrease exponentially with the increase of filtration duration. In accordance with the flux of filtrate approached to saturate, the variation of average Vpp tended to be nearly minimum. It can be readily observed for the changes of average Vpp that decreased from 3.02±0.05 V at the beginning of filtration to 1.73±0.25 V at 100 min duration after filtration with the humic acid solution of 4 ppm. Moreover, the fouling of the humic acid on the membrane was not homogeneously distributed. The acoustic impedance mismatch between the fouling of humic acid and PVDF membrane led the amplitude of ultrasonic signals reflected from the membrane surface to decrease with the increase of fouling deposition. C-scan results indicated that fouling deposition is a both temporal- and spatial-dependent process and that may be feasible to be sensitively and rapidly evaluated by high frequency ultrasound image incorporated with the analysis method.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75144306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A matrix phased array system for 3D high frame-rate imaging of the carotid arteries","authors":"M. Docter, R. Beurskens, G. Férin, P. Brands, J. Bosch, N. de Jong","doi":"10.1109/ULTSYM.2010.5935718","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935718","url":null,"abstract":"We are developing a volumetric ultrasound system for high frame-rate imaging of the carotid artery. It will be used in early detection of atherosclerosis, specifically aiming at visualization of neovascularization inside vulnerable plaque. These small vessels will be visualized in 3D by harmonic imaging of ultrasound contrast agents. The main parts of the ultrasound system are a 1024 element matrix array, a 128 channel transmitter-receiver and custom multiplexer electronics. This paper discusses the design and results of individual elements and corresponding multiplexer channels of our prototype system. We measured a transmit bandwidth of 80%, a center frequency of 7.9 MHz, a pressure of 29 kPa/V at the transducer's surface, and > 95% well-functioning elements, which meets our requirements. A volume frame rate of 1.9 kHz is achievable.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75493540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superharmonic imaging based on chirps","authors":"M. Danilouchkine, P. van Neer, G. Matte, M. Voormolen, M. Verweij, N. de Jong","doi":"10.1109/ULTSYM.2010.5935886","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935886","url":null,"abstract":"In medical ultrasound harmonic images of biological tissue are commonly obtained by analyzing the reflected echoes from the 2nd harmonic band. A new modality dubbed super-harmonic imaging (SHI) targets a combination of the 3rd–5th harmonics. SHI is expected to yield enhanced spatial resolution and thus to increase the quality of echographic images. On the other hand, those images obtained using short imaging pulses are susceptible to so-called multiple axial reflection artifacts, stemming from the troughs in between harmonics in the frequency domain. The recently proposed dual-pulse frequency compounding method suppresses these artifacts but reduces the frame rate by a factor of 2. In this work we research the feasibility of employing a chirp protocol to perform SHI without compromising the frame rate. The chirp protocol was implemented using an interleaved phased array transducer (44 elements tuned at 1 MHz, 44 elements at 3.7 MHz) in combination with a fully programmable ultrasound system. The transducer was mounted in the side of a water-filled tank. Linear chirps with a center frequency of 1 MHz and a bandwidth of 40% were used as excitation pulses. Radio frequency traces were recorded at the focal plane along the lateral axis using a hydrophone, filtered over the superharmonic band and convolved with a decoding signal to obtain point spread functions (PSFs). The decoding signal was acquired by simulating the emitted beam using the KZK method for a rectangular aperture. The decoded superharmonic chirp had an SNR of 35–40 dB. Comparing to a the 3rd harmonic produced by a 2.5 cycle 1 MHz Gaussian apodized sine burst transmission the lateral beam width of the superharmonic chirp signal is 0.8 and 0.9 times that of the 3rd harmonic at the −6 dB and −20 dB levels respectively. Regarding the axial beam width, the superharmonic chirp signal has 0.9 and 0.8 times the axial beam width of the 3rd harmonic at the −6 dB and −20 dB levels respectively. The superharmonic chirp PSF is virtually free from imaging artifacts. Based on the SNR measurements the chirp protocol yields a sufficient dynamic range. The PSF has increased spatial resolution in comparison with the 3rd harmonic. The first in-vitro images show promise, but the decoding pulse requires improvement.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88599166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling nonlinear medical ultrasound via a linearized contrast source method","authors":"L. Demi, M. Verweij, N. D. Jong, K. V. Dongen","doi":"10.1109/ULTSYM.2010.5935497","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935497","url":null,"abstract":"Research on nonlinear medical ultrasound has been increased over the last decade and has resulted in a wide range of numerical methods for the modeling of the nonlinear distortion of a propagating pressure wave. However, when applied to realistic configurations, the majority of these methods are either computationally expensive or limited by the applied approximations. The Iterative Nonlinear Contrast Source (INCS) method is able to accurately compute the pulsed nonlinear pressure wave field that is generated in a large three-dimensional domain by an arbitrary transducer transmitting under a large steering angle. The method is based on the Neumann iterative solution of a nonlinear integral equation that is equivalent to the Westervelt equation. To improve the performance of the method, it would be beneficial to employ iterative schemes (e.g. Conjugate Gradient based schemes) that are efficient for solving linear integral equations. This motivates the development of a linearized version of the INCS method, as presented in this paper. To test the presented approach, a Bi-CGSTAB scheme is used to solve the linearized Westervelt equation. For the one-dimensional case, results are obtained and compared with the solution obtained with the original INCS method, and the Fubini solution. All the results have been obtained up to the third harmonic component and are in agreement with each other.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90746116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrasound and photoacoustic image-guided photothermal therapy using silica-coated gold nanorods: In-vivo study","authors":"Seungsoo Kim, Yun-Sheng Chen, G. Luke, M. Mehrmohammadi, J. Cook, S. Emelianov","doi":"10.1109/ULTSYM.2010.5935601","DOIUrl":"https://doi.org/10.1109/ULTSYM.2010.5935601","url":null,"abstract":"In nanoparticle mediated photothermal therapy, confirmation of nanoparticle delivery/deposition in a tumor before therapy and temperature monitoring during therapy are needed to optimize therapeutic outcomes. In this paper, we demonstrate that ultrasound and photoacoustic imaging techniques can plan and guide photothermal cancer therapy, using an in-vivo mouse model of subcutaneous cancer intravenously administrated with silica-coated gold nanorods.","PeriodicalId":6437,"journal":{"name":"2010 IEEE International Ultrasonics Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83552985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}