Echo Signal Attenuation Research Articles

Virtual elastography ultrasound via generative adversarial network for breast cancer diagnosis

Elastography ultrasound (EUS) imaging is a vital ultrasound imaging modality. The current use of EUS faces many challenges, such as vulnerability to subjective manipulation, echo signal attenuation, and unknown risks of elastic pressure in certain delicate tissues. The hardware requirement of EUS also hinders the trend of miniaturization of ultrasound equipment. Here we show a cost-efficient solution by designing a deep neural network to synthesize virtual EUS (V-EUS) from conventional B-mode images. A total of 4580 breast tumor cases were collected from 15 medical centers, including a main cohort with 2501 cases for model establishment, an external dataset with 1730 cases and a portable dataset with 349 cases for testing. In the task of differentiating benign and malignant breast tumors, there is no significant difference between V-EUS and real EUS on high-end ultrasound, while the diagnostic performance of pocket-sized ultrasound can be improved by about 5% after V-EUS is equipped.

Target Echo Detection Based on the Signal Conditional Random Field Model for Full-Waveform Airborne Laser Bathymetry

Airborne laser bathymetry (ALB) systems with digital full-waveform signal collection can obtain corresponding temporal positions from several backscattering surfaces by laser beam irradiation. This information can help describe the multi-elevation structures of the target and explore the echo signal attenuation response in different nonuniform mediums during laser propagation. Therefore, a full-waveform echo signal is quite practical for integrated water-land detection. However, the wavelength used in the ALB system is generally in the visible band range of 470~580 nm, and the received signal is constantly interfered with by many nontarget factors, such as imperfections in the receiving channel or the strong scattering from the transmission medium. The conventional processing method transforms nontarget interference into noise point cloud filtering or classification extraction, enabling the detection of a single surface or regular geometry. The accuracy of the identification and extraction for multi-elevation target surfaces echo signal is always reduced due to the significant noise signal intensity. We proposed a signal component detection method by constructing the echo signal feature functions and the conditional random field (CRF) model based on the full-waveform decomposition. The processing result for actual measurement data verified that the CRF strategy can effectively reduce the uncertainty of target surface detection. Compared with the single-beam echo sounder, the root mean square errors of the elevation deviation underwater were reduced by 3.2 cm and 4.9 cm respectively in the two different experimental areas.

The On-Line Monitoring of the Winding Deformation of Transformer Based on the Improved Ultrasonic Ranging Method

The assessment of the winding deformation of transformer has a certain practical significance. In this paper, an Improved Ultrasonic Ranging (IUR) method is proposed to assess the winding deformation of transformer. Firstly, the basic principle of winding deformation detection using ultrasonic and the working principle of detection device are discussed. Secondly, the impact of the factors such as transformer oil temperature and echo signal attenuation on the test results is analyzed. Then, a new IUR method is composed, which can realize the on-line monitoring of transformer winding deformation. Finally, an assessment equipment of transformer winding deformation based on the online monitoring is developed, and a prototype is used to test the transformer mode, proving that this method is feasible.

Abstract 5022: The Relationship Between Plasma Pentraxin 3 and Coronary Plaque Morphologies in Patients With Acute Coronary Syndrome

Background: Inflammation is a significant factor contributing to atherosclerotic plaque development. Several inflammatory markers have been used to detect high risk patients with acute phase of ischemic heart disease. Recently, the long pentraxin family member, pentraxin 3 (PTX3) has been reported to be a significant predictor for clinical outcome in patients with acute coronary syndrome (ACS). However, the relationship between PTX3 and coronary plaque components has not been fully clarified. We tried to investigate the difference of plaque morphologies on intravascular ultrasound (IVUS) in ACS lesions among with elevating PTX3 or without. Methods: Eighteen target lesions in 18 ACS patients (ST-elevation MI (STEMI); 17 patients, non-STEMI; 1 patients), who underwent preintervention virtual histology (VH) - IVUS, were investigated. PTX3 was collected from all patients before percutaneous coronary intervention. The lesions were divided into two groups; group A with PTX3 ≥ 4ng/ml and group B with PTX3<4ng/ml. The differences of plaque morphologies on VH-IVUS were evaluated between the two groups. The presence of thin-cap fibroatheromas (TCFA), defined as a necrotic core ≥ 10% of plaque area at the minimal lumen area site without overlying fibrous tissue in the presence of >40% plaque burden characteristic. The presence of echo signal attenuation (EA) on IVUS, which recently has been reported to be related with no-reflow after PCI, was defined as atherosclerotic plaque showing ultrasound signal attenuation without very high intensity echo reflectors. Results: An elevation of PTX3 (≥4.0ng/ml) was detected in 10 lesions (55.6%). Lesion vessel area (20.1±3.3mm 2 vs. 14.8±4.9mm 2 , p<0.01) and plaque volume (312±118mm 3 vs. 200±93mm 3 , P<0.05) was significantly greater in group A than group B. Remodeling index was not significant but tended to be higher in lesion with group A than group B (1.19±0.19 vs. 1.06±0.17, p=0.13). The frequency of EA (60.0% vs. 0.0%, p<0.05) and TCFA (50.0% vs. 0 %, p<0.05) was significantly higher in lesions with group A than group B. Conclusions: In ACS lesions, pentraxin 3 might be a significant predictor for the presence of large amount of unstable and vulnerable plaque compositions, which might lead to a poor clinical outcome after PCI.

Clinical Significance of Echo Signal Attenuation on Intravascular Ultrasound in Patients With Coronary Artery Disease

Atherosclerotic plaque that shows echo signal attenuation (EA) without associated bright echoes is sometimes observed by intravascular ultrasound but its clinical significance remains unclear. We investigated the impact of EA on coronary perfusion and evaluated the pathological features of plaque with EA. We studied 687 native coronary lesions in 687 consecutive patients (336 with acute coronary syndrome and 351 with stable angina pectoris) who underwent intravascular ultrasound before percutaneous coronary intervention. By subgroup analysis, 60 lesions (30 lesions with EA) treated with directional coronary atherectomy underwent pathological examination. The Thrombolysis in Myocardial Infarction (TIMI) flow grade and myocardial blush grade after percutaneous coronary intervention were compared between lesions with and without EA in 627 lesions except directional coronary atherectomy subgroup. EA was observed in 245 lesions (35.7%), and coronary flow after percutaneous coronary intervention was worse for lesions with EA than without (final TIMI grade of 0 to 2: 15.4% versus 2.4%, P<0.001; final myocardial blush grade of 0 to 2: 45.6% versus 21.4%, P<0.001). Multivariate analysis revealed a significant association between no reflow (TIMI grade 0 to 2) and EA (odds ratio, 5.59; 95% CI, 2.64 to 11.85; P<0.001), a baseline TIMI grade of 0 to 2 (odds ratio, 5.91; 95% CI, 2.79 to 12.5; P<0.001), and a large reference area (odds ratio, 3.08; 95% CI, 1.40 to 6.76; P=0.005) after controlling for other associated factors. Pathological examination revealed a significantly higher frequency of lipid-rich plaque with microcalcification in lesions with EA. Atherosclerotic plaque with EA showed a significant association with no reflow after percutaneous coronary intervention, suggesting the existence of fragile components susceptible to distal embolization.

Abstract 6181: ST Segment Resolution and Pathological Findings of Aspirated Materials in Patients with ST Elevation Acute Myocardial Infarction

Early resolution of ST-segment elevation (STR) is a potent predictor of better clinical outcome after PCI in ST elevation acute myocardial infarction (STEMI). The aim of this study was to determine the association of aspirated materials and serial change of ST elevation. We studied 150 consecutive STEMI patients with assessable ECG recording, in whom standard PCI was performed with the adjunctive use of aspiration thrombectomy. STR(+) was defined as more than 50% resolution of ST-segment elevation at 60min after PCI. Aspirated materials were pathologically classified into thrombus only group (fresh, lytic, or organized) or thrombus and atheroma complex group, and compared between STR(+) and STR(−). TIMI flow grade, IVUS findings after aspiration(ruptured plaque, calcification, thrombus and echo signal attenuation), area under the curve (AUC) of CK-MB release, and pathological findings were also compared between the two groups. Seventy-six patients (50.6%) showed STR and 74 patients didn’t. RCA culprit lesion was significantly more frequent in STR(+)(P&lt;0.05). There was no significant difference in other patient characteristics or IVUS findings in the present cohort. AUC of CK-MB was lower in STR(+)(p=0.02). TIMI 3 flow was more frequently achieved in STR(+)(p&lt;0.05). Fresh thrombus was more frequent in STR(+)(p&lt;0.05), whereas atheromatous component and lytic or organized thrombus were frequently observed in STR(−)(p&lt;0.05). Culprit lesions in STEMI, when atheroma and thrombus complex with lytic or organized thrombus was aspirated, caused more myocardial damage and less frequent STR.

Coherent population transfer in molecules coupled with a dissipative environment by intense ultrashort chirped pulse. II. A simple model

We have developed a simple and physically clear picture of adiabatic rapid passage (ARP) in molecules in solution by careful examination of all the conditions needed for ARP. The relaxation effects were considered in the framework of the Landau-Zener model for random crossing of levels. The model enables us to include into consideration non-Markovian Gaussian-correlated noise. It explains all the numerical results obtained in the first paper of the series [B. D. Fainberg and V. A. Gorbunov, J. Chem. Phys. 117, 7222 (2002)], in particular, that for positive chirp pulse excitation relaxation favors more efficient population transfer with respect to the relaxation-free system with frozen nuclear motion. We also relate parameters of non-Markovian Gaussian-correlated noise with irreversible dephasing time of an optical transition by calculating the photon echo signal attenuation.

Measurement of compartment size in q-space experiments: Fourier transform of the second derivative.

Restricted diffusion in compartmentalized systems can lead to spatial coherence phenomena being observed in q-space plots from pulsed field gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) experiments. The underlying features observed in these plots contain information on the geometry of the compartments that is otherwise difficult to obtain. A numerical procedure is proposed that accentuates these coherence features: the data are weighted with a bell-shaped window function, interpolated with a shifting cubic spline, and then the second derivative is taken prior to Fourier transformation. The window function provides apodization of the noisy data at high q values, while it and the second derivative are equivalent to applying a high-pass filter to remove the zero- or low-frequency components in the echo-signal attenuation. Using a combination of theory, Monte Carlo simulations, and data from PGSE NMR experiments on human red blood cells, we demonstrate this to be a valuable processing tool for delineating the underlying coherence features. It should prove particularly useful where the coherence features are poorly defined or where more than one pattern is present in a q-space plot.

Diffusion measurements with the pulsed gradient nonlinear spin echo method

Spin echo signal attenuation by diffusion is examined for coherence evolution in the course of ordinary pulsed gradient spin echoes and for nonlinear evolution in the presence of a spatially modulated demagnetizing field. It is shown, that, for given field gradient pulse widths (or equivalently for a given gradient strength), echo attenuation by diffusion is much more efficient for nonlinear echoes than for Hahn echoes. Remarkably, in the case of nonlinear echoes the refocusing process is spoiled by diffusion not only during the gradient intervals but also thereafter. The effect of displacements occurring in the gradient intervals is enhanced according to the order of the nonlinear echo the pulse sequence is adjusted for. A second attenuation mechanism takes place after the gradient pulses due to displacements in the presence of the spatially modulated demagnetizing field. This effect even occurs when the gradient intervals are too short to contribute. A complete formalism is presented describing all features of the test experiments. It is shown that nuclear magnetic resonance diffusometry based on nonlinear echo signals permits one to measure small diffusion coefficients with moderate field gradients. Nonlinear echo experiments demonstrate that the coherence pathway dominating by far is of a purely single-quantum nature.