Novel Method for Vessel Cross-Sectional Shear Wave Imaging

Many studies have investigated the applications of shear wave imaging (SWI) to vascular elastography, mainly on the longitudinal section of vessels. It is important to investigate SWI in the arterial cross section when evaluating anisotropy of the vessel wall or complete plaque composition. Here, we proposed a novel method based on the coordinate transformation and directional filter in the polar coordinate system to achieve vessel cross-sectional shear wave imaging. In particular, ultrasound radiofrequency data were transformed from the Cartesian to the polar coordinate system; the radial displacements were then estimated directly. Directional filtering was performed along the circumferential direction to filter out the reflected waves. The feasibility of the proposed vessel cross-sectional shear wave imaging method was investigated through phantom experiments and ex vivo and in vivo studies. Our results indicated that the dispersion relation of the shear wave (i.e., the guided circumferential wave) within the vessel can be measured via the present method, and the elastic modulus of the vessel can be determined.     

Quantitative Assessment of Arterial Wall Biomechanical Properties Using Shear Wave Imaging

A new ultrasound-based technique is proposed to assess the arterial stiffness: the radiation force of an ultrasonic beam focused on the arterial wall induces a transient shear wave (∼10 ms) whose propagation is tracked by ultrafast imaging. The large and high-frequency content (100 to 1500 Hz) of the induced wave enables studying the wave dispersion, which is shown experimentally in vitro and numerically to be linked to arterial wall stiffness and geometry. The proposed method is applied in vivo. By repeating the acquisition up to 10 times per second (theoretical maximal frame rate is ∼100 Hz), it is possible to assess in vivo the arterial wall elasticity dynamics: shear modulus of a healthy volunteer carotid wall is shown to vary strongly during the cardiac cycle and measured to be 130 ± 15 kPa in systole and 80 ± 10 kPa in diastole. (E-mail: mathieu.couade@gmail.com)     

Multidirectional Estimation of Arterial Stiffness Using Vascular Guided Wave Imaging with Geometry Correction

We previously found that vascular guided wave imaging (VGWI) could non-invasively quantify transmural wall stiffness in both the longitudinal (r–z plane, 0°) and circumferential (r–θ plane, 90°) directions of soft hollow cylinders. Arterial stiffness estimation in multiple directions warrants further comprehensive characterization of arterial health, especially in the presence of asymmetric plaques, but is currently lacking. This study therefore investigated the multidirectional estimation of the arterial Young's modulus in a finite-element model, in vitro artery-mimicking phantoms and an excised porcine aorta. A longitudinal pre-stretch of 20% and/or lumen pressure (15 or 70?mm Hg) was additionally introduced to pre-condition the phantoms for emulating the intrinsic mechanical anisotropy of the real artery. The guided wave propagation was approximated by a zero-order antisymmetric Lamb wave model. Shape factor, which was defined as the ratio of inner radius to thickness, was calculated over the entire segment of each planar cross section of the hollow cylindrical structure at a full rotation (0°–360° at 10° increments) about the radial axis. The view-dependent geometry of the cross segment was found to affect the guided wave propagation, causing Young's modulus overestimation in four angular intervals along the propagation pathway, all of which corresponded to wall regions with low shape factors (<1.5). As validated by mechanical tensile testing, the results indicate not only that excluding the propagation pathway with low shape factors could correct the overestimation of Young's modulus, but also that VGWI could portray the anisotropy of hollow cylindrical structures and the porcine aorta based on the derived fractional anisotropy values from multidirectional modulus estimates. This study may serve as an important step toward 3-D assessment of the mechanical properties of the artery.     

Intermittent, moderate-intensity aerobic exercise for only eight weeks reduces arterial stiffness: evaluation by measurement of stiffness parameter and pressure–strain elastic modulus by use of ultrasonic echo tracking

Background and purpose

Aerobic exercise has been reported to be associated with reduced arterial stiffness. However, the intensity, duration, and frequency of aerobic exercise required to improve arterial stiffness have not been established. In addition, most reports base their conclusions on changes in pulse wave velocity, which is an indirect index of arterial stiffness. We studied the effects of short-term, intermittent, moderate-intensity exercise training on arterial stiffness based on measurements of the stiffness parameter (β) and pressure–strain elastic modulus (E _p), which are direct indices of regional arterial stiffness.

Methods

A total of 25 young healthy volunteers (18 men) were recruited. By use of ultrasonic diagnostic equipment we measured β and E _p of the carotid artery before and after 8 weeks of exercise training.

Results

After exercise training, systolic pressure (P _s), diastolic pressure (P _d), pulse pressure, systolic arterial diameter (D _s), and diastolic arterial diameter (D _d) did not change significantly. However, the pulsatile change in diameter ((D _s ? D _d)/D _d) increased significantly, and β and E _p decreased significantly.

Conclusions

For healthy young subjects, β and E _p were reduced by intermittent, moderate-intensity exercise training for only 8 weeks.     

Acute Effects of Static Stretching on Muscle Hardness of the Medial Gastrocnemius Muscle Belly in Humans: An Ultrasonic Shear-Wave Elastography Study

This study investigated the acute effects of static stretching (SS) on shear elastic modulus as an index of muscle hardness and muscle stiffness and the relationship between change in shear elastic modulus and change in muscle stiffness after SS. The patients were 17 healthy young males. Muscle stiffness was measured during passive ankle dorsiflexion using a dynamometer and ultrasonography before (pre) and immediately after (post) 2 min of SS. In addition, shear elastic modulus was measured by a new ultrasound technique called ultrasonic shear wave elastography. The post-SS values for muscle stiffness and shear elastic modulus were significantly lower than the pre-SS values. In addition, Spearman's rank correlation coefficient indicated a significant correlation between rate of change in shear elastic modulus and rate of change in muscle stiffness. These results suggest that SS is an effective method for decreasing shear elastic modulus as well as muscle stiffness and that shear elastic modulus measurement using the shear wave elastography technique is useful in determining the effects of SS.     

Viscoelastic Properties of Normal and Infarcted Myocardium Measured by a Multifrequency Shear Wave Method: Comparison with Pressure-Segment Length Method

Our aims were (i) to compare in vivo measurements of myocardial elasticity by shear wave dispersion ultrasound vibrometry (SDUV) with those by the conventional pressure-segment length method, and (ii) to quantify changes in myocardial viscoelasticity during systole and diastole after reperfused acute myocardial infarction. The shear elastic modulus (μ₁) and viscous coefficient (μ₂) of left ventricular myocardium were measured by SDUV in 10 pigs. Young's elastic modulus was independently measured by the pressure-segment length method. Measurements made with the SDUV and pressure-segment length methods were strongly correlated. At reperfusion, μ₁ and μ₂ in end-diastole were increased. Less consistent changes were found during systole. In all animals, μ₁ increased linearly with left ventricular pressure developed during systole. Preliminary results suggest that μ₁ is preload dependent. This is the first study to validate in vivo measurements of myocardial elasticity by a shear wave method. In this animal model, the alterations in myocardial viscoelasticity after a myocardial infarction were most consistently detected during diastole.     

Evaluation of the Effect of an Anisotropic Medium on Shear Wave Velocities of Intra-Muscular Gelatinous Inclusions

In highly anisotropic biological tissues such as muscle or tendons, calculating Young's modulus from the shear wave speed (c_sw) by using shear wave elastography (SWE) involves a complex transversally isotropic rheological model not yet used in common practice. To our knowledge, the effect of muscle anisotropy on c_sw of intra-muscular lesions has not yet been investigated. The objective of our study was to define the effect of an anisotropic medium on c_sw of intra-muscular gelatinous inclusions. We conducted a prospective monocentric, in vitro study in order to examine the quantitative and qualitative SWE behavior of a 9-mm gelatinous intra-muscular implant depending on the orientation of the probe relative to the muscle fibers. There were very significant differences in the prevalence of SWE signal void (p < 0.01) and in the c_sw (p < 0.01) in the gelatinous intra-muscular implants depending on the orientation of the probe relative to the fibers. Performing the c_sw measurements of centimetric intra-muscular lesions by orienting the probe perpendicular to the fibers decreases the probability of artifacts occurring at high intensity interfaces.     

Entry and passage behavior of biological cells in a constricted compliant microchannel

We report an experimental and theoretical investigation of the entry and passage behaviour of biological cells (HeLa and MDA-MB-231) in a constricted compliant microchannel. Entry of a cell into a micro-constriction takes place in three successive regimes: protrusion and contact (cell protrudes its leading edge and makes a contact with the channel wall), squeeze (cell deforms to enter into the constriction) and release (cell starts moving forward). While the protrusion and contact regime is insensitive to the flexibility of the channel, the squeeze zone is significantly smaller in the case of a more compliant channel. Similarly, in the release zone, the acceleration of the cells into the microconstriction is higher in the case of a more compliant channel. The results showed that for a fixed size ratio ρ and E_c, the extension ratio λ decreases and transit velocity U_c increases with increase in the compliance parameter f_p. The variation in the cell velocity is governed by force due to the cell stiffness F_s as well as that due to the viscous dampening F_d, explained using the Kelvin–Voigt viscoelastic model. The entry time t_e = m(ρ)^k₁(1 + f_p)^k₂(E_c)^k₃ and induced hydrodynamic resistance of a cell ΔR_c/R = k(ρ)^a(1 + k_ff_p)^b(k_EE_c)^c were correlated with cell size ratio ρ, Young''s modulus E_c and compliance parameter f_p, which showed that both entry time t_e and the induced hydrodynamic resistance ΔR_c are most sensitive to the change in the compliance parameter f_p. This study provides understanding of the passage of cells in compliant micro-confinements that can have significant impact on mechanophenotyping of single cells.

We report an experimental and theoretical investigation of the entry and passage behaviour of biological cells (HeLa and MDA-MB-231) in a constricted compliant microchannel.     

Effects of nitric oxide and sodium nitroprusside on the intrinsic elastic properties of pressurized rat coronary artery

Summary— The study was designed to assess the influence of either nitric oxide (NO) or sodium nitroprusside and the absence of endothelium on the intrinsic elastic properties of coronary arteries from WKY rats. For this purpose, segments of the right interventricular coronary were mounted in an arteriograph where wall thickness and internal diameter were continuously monitored while intraluminal pressure was controlled in the absence of flow. To study the passive properties, pressure-diameter relationships were determined by measuring the corresponding internal diameter for each stepwise increase in intraluminal pressure. Thus, wall stress, strain and incremental elastic modulus (E_inc) were assessed in the following experimental conditions: control, incubation with nitro-L-arginine methyl ester (L-NAME, 100 μM) or L-NAME + L-arginine (L-arg, 100 μM), incubation with sodium nitroprusside (SNP, 100 μM), endothelium removal (CHAPS). The E_inc-stress relationship was not significantly different in the different experimental conditions, but values of E_inc plotted as function of strain were significantly decreased after L-NAME incubation and partly reversed after L-arg addition. The same effect was observed after endothelium destruction but to a lesser extent. After SNP incubation, values of E_inc were significantly decreased for small values of strain and increased for high values of this parameter. These results show that NO synthase inhibition induced, for a given strain, a decrease of elastic modulus in coronary arteries. It can be speculated that functional antagonism exerted by NO against spontaneous contractile tone was reduced. Thus, the smooth muscle cells were in a greater state of activation and probably more strongly involved in the intrinsic elastic properties of this preparation. However, an unexplained effect of NO on wall stiffness cannot be excluded. Conversely, SNP increased the initial diameter and induced an initial decrease in stiffness followed by a subsequent increase. After endothelium destruction, stiffness was significantly decreased compared to control conditions. It can be concluded that NO modulates the intrinsic elastic properties of the coronary arteries through smooth muscle cell relaxation. Furthermore, results with SNP support the hypothesis that the lower the state of activation of the smooth muscle cells, the higher the elastic modulus of the arterial wall in this coronary artery preparation.     

Similar Reproducibility for Strain and Shear Wave Elastography in Breast Mass Evaluation: A Prospective Study Using the Same Ultrasound System

The objective of this study was to evaluate the inter-operator reproducibility of strain elastography (SE) and shear wave elastography (SWE) in three groups: all lesions, benign lesions and malignant lesions. Ninety-one lesions from ninety-one women were examined by SE and SWE from January 2017 to December 2017 by two radiologists. The reproducibility of elastic score, SE strain ratio and SWE Young's modulus between operators was prospectively evaluated. There was good agreement on elasticity score, with κ values of 0.711, 0.640 and 0.766. The intra-class correlation coefficients of the strain ratio, mean elastic modulus (E_mean), maximum elastic modulus (E_max) and elastic modulus standard deviation (E_sd) ranged from 0.723–0.876, which indicated good and excellent agreement. We concluded that both SE and SWE had good reproducibility among different operators using the same probe in the same ultrasound instrument. Strain elasticity score was more consistent among operators in malignant breast tumors. There was better agreement on strain elastic ratio and shear wave elasticity among operators in benign breast lesions.     

Carotid Artery Stiffness Mechanisms in Hypertension and Their Association with Echolucency and Texture Features: The Multi-ethnic Study of Atherosclerosis (MESA)

Arterial stiffness, echolucency and texture features are altered with hypertension and associated with increased cardiovascular disease risk. The relationship between these markers and structural and load-dependent artery wall changes in hypertension are poorly understood. The Multi-ethnic Study of Atherosclerosis (MESA) is a longitudinal study of 6814 adults from six communities across the United States designed to study subclinical cardiovascular disease. From B-mode imaging of the right common carotid artery at the baseline MESA examination, we calculated carotid artery Young's elastic modulus (YEM, n = 5894) and carotid artery gray-scale texture features (n = 1403). The standard YEM calculation represented total arterial stiffness. Structural stiffness was calculated by adjusting YEM to a standard blood pressure of 120/80 mm Hg with participant-specific models. Load-dependent stiffness was the difference between total and structural stiffness. We found that load-dependent YEM was elevated in hypertensive individuals compared with normotensive individuals (35.7 ± 105.5 vs. –62.0 ± 112.4 kPa, p < 0.001) but that structural YEM was similar (425.3 ± 274.8 vs. 428.4 ± 293.0 kPa, p = 0.60). Gray-scale measures of heterogeneity in carotid artery wall texture (gray-level difference statistic contrast) had small but statistically signification correlations with carotid artery stiffness mechanisms. This association was positive for structural YEM (0.107, p < 0.001), while for load-dependent YEM, the association was negative (–0.064, p = 0.02). In conclusion, increased arterial stiffness in hypertension was owing solely to the non-linear mechanics of having higher blood pressure, not structural changes in the artery wall, and high load-dependent stiffness was associated with a more homogenous carotid artery wall texture. This is potentially related to arterial remodeling associated with subclinical atherosclerosis and future cardiovascular disease development. These results also indicate that gray-scale texture features from ultrasound imaging had a small but statistically significant association with load-dependent arterial stiffness and that gray-scale texture features may be partially load dependent.     

Value of Shear Wave Elastography in the Diagnosis of Gouty and Non-Gouty Arthritis

Our aim was to analyze the diagnostic performance of shear wave elastography (SWE) in the diagnosis of gouty arthritis (GA) and non-gouty arthritis (non-GA). Thirty-nine patients in the GA group and 55 patients in the non-GA group were included in the study. Based on the echo intensity of the joint lesions, the GA group was subdivided into hypo-echoic GA, slightly hyper-echoic GA and hyper-echoic GA subgroups. Quantitative SWE features were evaluated and receiver operating characteristic analysis was performed. On the basis of the study, the elastic modulus (E_max), mean elastic modulus (E_mean), minimum elastic modulus (E_min) and elastic modulus standard deviation (E_SD) were significantly higher in the GA group than in the non-GA group and were highest in the hyper-echoic GA subgroup (p < 0.01 for all). E_min, E_mean and E_max were significantly higher in the hyper-echoic GA subgroup than in the hypo-echoic GA subgroup and non-GA group (p < 0.001 for all), and E_SD was significantly higher in the hyper-echoic GA subgroup than in the non-GA group (p = 0.001). E_min, E_mean, E_max and E_SD were higher in the hypo-echoic GA subgroup than in the non-GA group, and the differences were significant (p < 0.001 for all). Based on the hypo-echoic GA subgroup and non-GA group, areas under the receiver operating characteristic curves for the prediction of GA were 0.749 for E_min, 0.877 for E_mean, 0.896 for E_max and 0.886 for E_SD, with optimal cutoff values of 29.40 kPa for E_min, 45.35 kPa for E_mean, 67.54 kPa for E_max and 7.85 kPa for E_SD. Our results indicate that SWE can differentially diagnose GA and non-GA, especially when the ultrasound manifestations are not typical.     

Influence of the order of aerobic and resistance exercise on hemodynamic responses and arterial stiffness in young normotensive individuals

AimsTo investigate the effects of a combination of aerobic and resistance exercises and the inverse sequence on the hemodynamic parameters and indicators of arterial stiffness in healthy young adult subjects.MethodsFifteen subjects were randomized in a crossover procedure according to two experimental conditions: combined aerobic exercise (30 min of treadmill running, 75–80% – peak VO₂) followed by resistance exercise (5 exercises, 3 sets – 10 RM) (AR) or vice versa (RA). Data of the hemodynamic parameters and arterial stiffness were obtained at baseline and after exercise (post-10, post-20, and post-30 min). Two-way ANOVA for repeated measurements was performed with the Newman–Keuls post-hoc. The significance level adopted was p < 0.05.ResultsThe results of the two-way ANOVA for repeated measures were not statistically significant for brachial and central systolic and diastolic blood pressure, respectively, or arterial stiffness indicators: reflected wave indicators and pulse wave velocity (P > 0.05). Statistically significant interactions were observed before and after the exercise sessions for heart rate and rate pressure product (P = < 0.001).ConclusionThe performance order of aerobic exercise followed by resistance exercise (AR) and the reverse order (RA) present similar changes in blood pressure (BP) and arterial stiffness. However, resistance exercise before aerobic exercise promotes increases in heart rate and rate product pressure.     

Probing the Mechanical Properties of Large Arteries by Measuring Their Deformation In Vivo with Ultrasound

Aging and cardiovascular diseases (CVDs) may alter the microstructures of arteries and hence their mechanical properties. Therefore, the measurement of intrinsic artery mechanical properties in vivo can provide valuable information in understanding aging and CVDs and is of clinical significance. The accuracy of advanced ultrasound imaging techniques in measuring the deformation of large arteries under blood pressure is good. However, the assessment of arterial stiffness in vivo remains a challenge. An inverse method to infer the constitutive parameters of arteries in vivo from the blood pressure–arterial radius relationship (P–r curve) is proposed here. The stability analysis reveals that a key constitutive parameter, b_θ, which measures the circumferential hardening of an artery, can be reliably identified. An in vivo experiment was performed on the common carotid arteries of 41 healthy volunteers (age: 37 ± 17 y). The value of b_θ varies significantly (from 0.55 ± 0.15 for the young group to 0.93 ± 0.29 for the older group, p < 0.01) and is positively correlated with age (r = 0.673, p < 0.01). Furthermore, our theoretical analysis and experimental study have revealed a strong correlation between the clinic-used stiffness index $\mathbf{\beta }$ and b_θ. This study shows that the arterial material parameter b_θ can be measured in vivo, which makes it promising as a new biomarker in the diagnosis of CVDs.     

Non-invasive Assessment of Changes in Muscle Injury by Ultrasound Shear Wave Elastography: An Experimental Study in Contusion Model

The present study investigated the potential of ultrasound shear wave elastography (SWE) in assessment of muscle stiffness in muscle injury. SWE was performed on the injured muscle in 30 New Zealand rabbits that were randomly assigned to three groups: the contusion group, which was not treated with an efficient therapeutic strategy after muscle injury; the treatment group, which was treated with a therapeutic scheme after muscle injury; and the healthy group, which was not injured and served as a control. Both the mean Young's modulus (E_mean) and the maximum Young's modulus (E_max) were obtained pre-injury and 0.5, 1, 3, 5, 7, 14 and 28 d post-injury. At these time points, a rabbit in each group was randomly selected for biopsy for histopathological observation as well as comparison with Young's modulus. Eventually, all muscle tissues were collected for histologic analysis of collagen fiber formation. The contusion group had the highest Young's modulus, followed by the treatment group and then the healthy group (p < 0.05). In both the contusion and treatment groups, E_mean and E_max gradually increased within 1–3 d after injury, followed by a gradual decrease. Compared with the healthy group, histopathologic analysis of the contusion and treatment groups revealed the myofibril destruction process, inflammatory reaction and myofibril regeneration. The amount of collagen fibers in the contusion group was maximal compared with the treated and healthy groups (p?=?0.001 and p < 0.001, respectively). There were more collagen fibers in the treatment group than in the healthy group (p?=?0.003). The abundance of collagen fibers was positively correlated with the value of Young's modulus (E_mean: r?=?0.706, p < 0.001; E_max: r?=?0.761, p < 0.001). Thus, SWE can be used to detect pathologic changes in injured muscle and to monitor therapeutic effects.     

Arterial Stiffness Assessment by Shear Wave Elastography and Ultrafast Pulse Wave Imaging: Comparison with Reference Techniques in Normotensives and Hypertensives

Shear wave elastography and ultrafast imaging of the carotid artery pulse wave were performed in 27 normotensive participants and 29 age- and sex-matched patients with essential hypertension, and compared with reference techniques: carotid–femoral pulse wave velocity (cfPWV) determined via arterial tonometry and carotid stiffness (carPWV) determined via echotracking. Shear wave speed in the carotid anterior (a–SWS) and posterior (p-SWS) walls were assessed throughout the cardiac cycle. Ultrafast PWV was measured in early systole (ufPWV–FW) and in end-systole (dicrotic notch, ufPWV-DN). Shear wave speed in the carotid anterior appeared to be the best candidate to evaluate arterial stiffness from ultrafast imaging. In univariate analysis, a-SWS was associated with carPWV (r?=?0.56, p?=?0.003) and carotid-to-femoral PWV (r?=?0.66, p < 0.001). In multivariate analysis, a–SWS was independently associated with age (R²?=?0.14, p?=?0.02) and blood pressure (R²?=?0.21, p?=?0.004). Moreover, a–SWS increased with blood pressure throughout the cardiac cycle and did not differ between normotensive participants and patients with essential hypertension when compared at similar blood pressures.     

Quantitative Evaluation of Denervated Muscle Atrophy with Shear Wave Ultrasound Elastography and a Comparison with the Histopathologic Parameters in an Animal Model

This study explored the efficacy of shear wave ultrasound elastography (SWUE) for quantitative evaluation of denervated muscle atrophy in a rabbit model. The elastic modulus of the triceps surae muscle was measured with SWUE and compared with histopathologic parameters at baseline and at various post-denervation times (2, 4 and 8?wk) with 10 animals in each group. Our results revealed that the elastic modulus of denervated muscle was significantly lower at 2?wk but higher at 8?wk compared with that at the baseline (p?<0.05), and no significant difference was found between the elastic modulus at 4?wk and that at the baseline (p?>?0.05). The wet-weight ratio and the muscle fiber cross-sectional area of the denervated muscle decreased gradually during the 8?wk post-denervation together with a gradual increase of the collagen fiber area (p?<0.05). In conclusion, SWUE was useful for quantitative evaluation of muscle denervation. The decreased elastic modulus might be an early sign of denervated muscle atrophy.     

Shear Wave Elastography Quantifies Stiffness in Ex Vivo Porcine Artery with Stiffened Arterial Region

Five small porcine aortas were used as a human carotid artery model, and their stiffness was estimated using shear wave elastography (SWE) in the arterial wall and a stiffened artery region mimicking a stiff plaque. To optimize the SWE settings, shear wave bandwidth was measured with respect to acoustic radiation force push length and number of compounded angles used for motion detection with plane wave imaging. The mean arterial wall and simulated plaque shear moduli varied from 41 ± 5 to 97 ± 10 kPa and from 86 ± 13 to 174 ± 35 kPa, respectively, over the pressure range 20–120 mmHg. The results revealed that a minimum bandwidth of approximately 1500 Hz is necessary for consistent shear modulus estimates, and a high pulse repetition frequency using no image compounding is more important than a lower pulse repetition frequency with better image quality when estimating arterial wall and plaque stiffness using SWE.     

Pressure pulse velocity is related to the longitudinal elastic properties of the artery

It is known that arteries in their natural position are always subject to a longitudinal stress. However, the effect of this strong longitudinal tension has seldom been addressed. In this paper, we point out that the traditional pulse wave velocity formulae considering only the circumferential elasticity fail to include all the important energies. We present a vigorous derivation of a pressure wave equation, the pressure wave equation with total energy, which considers all the important energies of the whole arterial system by treating the arterial wall and the blood as one system. Our model proposes that the energy transport in the main arterial system is primarily via the transverse vibration motion of the elastic wall. The final equation indicates that the longitudinal stress is essential and the high frequency phase velocity is related to the longitudinal tension along the arterial wall and its Young's shearing modulus. By applying this equation, we suggest that longitudinal elastic property is an important factor in hemodynamics and in the treatment of cardiovascular diseases.     

实时剪切波弹性成像评价兔单纯性脂肪肝肝硬度

目的 采用实时剪切波弹性成像(SWE)技术监测兔单纯性脂肪肝在不同时间段的硬度。方法 将60只雄性日本大耳白兔随机分为两组,高脂组及对照组各30只。对高脂组喂养高脂饲料建立单纯性脂肪肝模型,对照组喂饲基础饲料,采用SWE测量两组肝脏不同时间段(喂养前,喂养后4、8、12、16周)的弹性模量值。结果 12周后,高脂组肝脏弹性模量最大值和平均值均高于对照组,差异有统计学意义(P均<0.05)。平均弹性模量值与病理分期呈正相关(r=0.60,P=0.03)。结论 SWE可定量测量脂肪肝硬度并准确地评价脂肪肝程度。