The most troublesome of ultrasonic B-mode imaging is the difficulty of accurately diagnosing cancers, benign tumors, and cysts because they appear similar to each other in B-mode images. The human soft tissue has different physical characteristics of ultrasound depending on whether it is normal or not. In particular, cancers in soft tissue tend to be harder than the surrounding tissue. Thus, ultrasound elasticity imaging can be advantageously used to detect cancers. To measure elasticity, a mechanical force is applied to a region of interest, and the degree of deformation measured is rendered as an image. Depending on the method of applying stress and measuring strain, different elasticity imaging modalities have been reported, including strain imaging, sonoelastography, vibro-acoustography, transient elastography, acoustic radiation force impulse imaging, supersonic imaging, and strain-rate imaging. In this paper, we introduce various elasticity imaging methods and explore their technical principles and characteristics.
Elasticity Imaging Techniques ; Elasticity* ; Humans ; Methods ; Ultrasonics ; Ultrasonography*

Noticing the phenomenon that biological tissues will change its elasticity by orders of magnitude after it was frozen, we proposed in principle the strategy of using ultrasound elastography to monitor the formation and thawing of the iceball when performing a cryosurgery. Following our former theoretical evaluation, conceptual experiments were designed to apply ultrasound elastography to monitor three kinds of testing samples which includes: phantom embedded with glass block, phantom with tissues at normal temperature and phantom with frozen tissues inside. It was demonstrated for the first time that the ultrasound elastography could provide a high contrast picture on the ice ball during cryosurgery. The measurement errors involved in the application of the method was preliminarily analyzed and approaches to further improve the method were pointed out. With a much different value in elastography than that of water, monitoring the ice ball, the imaging target in clinics, is expected to be an important area for the application of ultrasound elastography.
Cryosurgery ; methods ; Elasticity Imaging Techniques ; methods ; Phantoms, Imaging ; Ultrasonics

No abstract available.
Elasticity Imaging Techniques/*methods ; Humans ; Musculoskeletal Diseases/*ultrasonography

Elastography is an ultrasound-based newer imaging technique that is currently being used for the evaluation of breast lesions and hepatic pathology. It is also being evaluated for characterizing lesions of the prostate, thyroid, cervix and lymph nodes. We have applied real-time sonoelastography to a variety of musculoskeletal pathologies and here we report the findings of elastography for the evaluation of various musculoskeletal pathologies. Elastography of musculoskeletal lesions is not yet being routinely used in clinical practice, but it is being extensively researched.
Elasticity Imaging Techniques/*methods ; Humans ; Musculoskeletal Diseases/*ultrasonography

No abstract available.
Elasticity Imaging Techniques/*methods ; Humans ; Musculoskeletal Diseases/*ultrasonography

Portable wireless ultrasound has been emerging as a new ultrasound device due to its unique advantages including small size, lightweight, wireless connectivity and affordability. Modern portable ultrasound devices can offer high quality sonogram images and even multiple ultrasound modes such as color Doppler, echocardiography, and endovaginal examination. However, none of them can provide elastography function yet due to the limitations in computational performance and data transfer speed of wireless communication. Also phase-based strain estimator (PSE) that is commonly used for conventional elastography cannot be adopted for portable ultrasound, because ultrasound parameters such as data dumping interval are varied significantly in the practice of portable ultrasound. Therefore, this research aims to propose a new elastography method suitable for portable ultrasound, called the robust phase-based strain estimator (RPSE), which is not only robust to the variation of ultrasound parameters but also computationally effective. Performance and suitability of RPSE were compared with other strain estimators including time-delay, displacement-gradient and phase-based strain estimators (TSE, DSE and PSE, respectively). Three types of raw RF data sets were used for validation tests: two numerical phantom data sets modeled by an open ultrasonic simulation code (Field II) and a commercial FEA (Abaqus), and the one experimentally acquired with a portable ultrasound device from a gelatin phantom. To assess image quality of elastograms, signal-to-noise (SNRe) and contrast-to-noise (CNRe) ratios were measured on the elastograms produced by each strain estimator. The computational efficiency was also estimated and compared. Results from the numerical phantom experiment showed that RPSE could achieve highest values of SNRe and CNRe (around 5.22 and 47.62 dB) among all strain estimators tested, and almost 10 times higher computational efficiency than TSE and DSE (around 0.06 vs. 5.76 s per frame for RPSE and TSE, respectively).
Dataset ; Echocardiography ; Elasticity Imaging Techniques ; Gelatin ; Methods ; Ultrasonics ; Ultrasonography

Recent studies have shown that real-time, two-dimensional shear-wave elastography (2D-SWE) can monitor liver fibrosis by measuring tissue elasticity (i.e., elastic modulus). Two clinical studies of 2D-SWE in the liver have shown that there are several practical issues that can compromise quantitation of liver tissue elasticity. Both general ultrasound (US) limitations and limitations in the 2D-SWE method itself resulted in significant variability in estimated liver elasticity. The most common US limitations were: poor acoustic window, limited penetration, and rib/lung shadows. The most common 2D-SWE limitations were: reverberations under the liver capsule, respiratory/cardiac motion, and vessel pulsation/loss of SWE signal. Based on these studies, scan protocols have been optimized to minimize the influence of these limitations on liver elasticity quantification. These refined protocols should move non-invasive SWE closer to becoming the preferred tool to diagnose and manage many chronic diseases of the liver.
Acoustics ; Artifacts* ; Chronic Disease ; Elasticity ; Elasticity Imaging Techniques* ; Fibrosis ; Liver Cirrhosis ; Liver* ; Methods ; Ultrasonography

OBJECTIVETo validate transient elastography (Fibroscan) in assessment of hepatic fibrosis in autoimmune hepatitis (AIH).

METHODSLiver stiffness was assessed using Fibroscan in totally 30 patients with AIH. We compared the results of Fibroscan with the Scheuer fibrosis stage in liver biopsy in each patient.

RESULTS4 patients were shown as liver fibrosis stage S0, 6 as S1, 5 as S2, 11 as S3 and 4 as S4. Failure of the Fibroscan measurement occurred in 1 case (3.3%) because of her increased body mass index (BMI). The stiffness of Fibroscan was significantly correlated with the liver biopsy fibrosis stage (r = 0.801, P less than 0.001). The liver stiffnesses between mild and moderate fibrosis (S0-2) and advanced fibrosis (S3-4) were significantly different (t = -3.937, P = 0.001).

CONCLUSIONTransient elastography (Fibroscan) is a promising non-invasive method for detection of fibrosis in patients with autoimmune hepatitis. Its use for the follow up and management of these patients and should be evaluated further.

Elasticity Imaging Techniques ; methods ; Hepatitis, Autoimmune ; diagnostic imaging ; Humans ; Liver ; diagnostic imaging ; Liver Cirrhosis ; diagnostic imaging

The variation of tissue elasticity or stiffness is related with diseases of tissue, so the characterization of tissue elasticity is important to diagnosis. There are four methods for ultrasonic characterization of tissue elasticity: imaging inspection techniques, vibration velocity measurements, quasi-static strain measurements and parametric methods. The theories of the method of vibration velocity measurements and the method of quasi-static strain measurements and their new developments are discussed in this paper. The applications and the problems of this technique are discussed also.
Biomechanical Phenomena ; Connective Tissue ; diagnostic imaging ; Elasticity ; Elasticity Imaging Techniques ; methods ; Humans ; Image Processing, Computer-Assisted ; methods ; Stress, Mechanical

BACKGROUNDTo compare the diagnostic values of magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI) in staging hepatic fibrosis (HF) in an animal model.

METHODSThis study consisted of 44 rabbits served as HF group and 9 normal rabbits. HF group was divided into two subgroups: Group A (n = 32) and Group B (n = 12). Rabbits in Group B were served as a complementary group when rabbits in Group A suddenly died during the study. Rabbits from control and Group A underwent abdominal MR imaging (MRI), MRE, and DWI. In Group A, random eight rabbits underwent MRI examinations at 4, 5, 6, 10 weeks after carbon tetrachloride oil subcutaneous injection. Liver stiffness (LS) and apparent diffusion coefficient (ADC) values of liver parenchyma were measured. The diagnostic performance of MRE and DWI for staging HF was compared using the receiver operating characteristic curve analysis on the basis of the histopathological analysis of HF.

RESULTSSignificant differences of LS and DWI values were present among HF stages (P < 0.005). The LS values measured on MRE (r = 0.838, P < 0.001) were more strongly correlated with the HF stages than with ADC values (r = -0.527, P < 0.001). The area under the receiver operating characteristic curve values of LS were significantly larger than those of DWI were for discriminating two stages of HF (0.979 vs. 0.712 for ≥ S1, 0.922 vs. 0.699 for ≥ S2). MRE showed higher specificity for predicting all stages of HF compared to DWI.

CONCLUSIONSMRE more strongly correlated with the HF stages than DWI and is more specific in predicting all HF stages.

Animals ; Diffusion Magnetic Resonance Imaging ; methods ; Elasticity Imaging Techniques ; methods ; Liver ; pathology ; Liver Cirrhosis ; diagnosis ; Rabbits