Quantitative Shear Wave Speed Assessment for Muscles With the Diagnosis of Taut Bands and/or Myofascial Trigger Points Using Probe Oscillation Shear Wave Elastography: A Pilot Study.

OBJECTIVE: To use probe oscillation shear wave elastography (PROSE) with two vibration sources to generate two shear waves in the imaging plane to quantitatively assess the shear wave speeds (SWSs) of muscles with and without the diagnosis of taut bands (TB) and/or myofascial trigger points (MTrPs). METHODS: Thirty-three patients were scanned with the PROSE technique. Shear waves were generated through continuous vibration of the ultrasound probe, while the shear wave motions were detected using the same probe. SWSs for the sides with and without TBs and/or MTrPs were computed and compared. The pressure pain thresholds (PPTs) were measured as an indicator of maximum pain tolerance of patients. The statistical differences between the SWSs with and without TBs and/or MTrPs with different PPT values were analyzed using the nonparametric Wilcoxon rank-sum test. RESULTS: The mean SWSs for the sides with TBs and/or MTrPs are faster than that of the contralateral side without TBs and/or MTrPs. A significant difference was observed between mean SWSs with and without TBs and/or MTrPs without any information of PPT, with rank-sum test P < .005. Additionally, with the information of PPT, a significant difference was observed between mean SWSs for the sides with and without TBs and/or MTrPs, for PPT values between 0 and 50 N/cm2 (P < .005), but for PPT values between 50 and 90 N/cm2 , it was difficult to differentiate mean SWSs with and without TBs and/or MTrPs. CONCLUSION: Our preliminary results show that SWSs measured from patients had a significant difference between the mean SWSs with and without TBs and/or MTrPs.

Shear wave-based sound touch elastography in liver fibrosis assessment for patients with autoimmune liver diseases.

BACKGROUND: Shear wave-based ultrasonic elastography (USE) has been widely used for the assessment of liver fibrosis in patients with chronic liver diseases (CLD). However, diagnostic criteria and accuracy vary between different etiologies and specific elastography techniques. We aimed to evaluate the tissue stiffness measured by shear wave-based sound touch elastography (STE) in staging liver fibrosis in patients with autoimmune liver diseases (AILD). METHODS: One hundred and two AILD patients who had undergone STE liver stiffness measurements (LSMs) by using a Resona 7 ultrasound system were retrospectively studied. With the Scheuer liver fibrosis staging system as the reference, we investigated the diagnostic performance and cutoff values of STE measured liver stiffness in staging liver fibrosis through receiver operating characteristic (ROC) curve analysis. Moreover, comparisons of areas under the curve (AUCs) were made between LSMs and calculated biomarker scores, including the aspartate aminotransferase (AST)-to-platelet ratio index (APRI), and fibrosis-4 (FIB-4) index. RESULTS: Median LSMs increased with the advancing fibrosis stages with values of 6.89 kPa (1.51 m/s), 8.00 kPa (1.63 m/s), 9.60 kPa (1.79 m/s), 11.37 kPa (1.95 m/s) and 14.50 kPa (2.20 m/s), from stage 0 to stage 4 respectively. The cutoff values of STE for identifying significant fibrosis (≥ stage 2), severe fibrosis (≥ stage 3) and cirrhosis (stage 4) were 9.07 kPa (1.74 m/s), 9.97 kPa (1.82 m/s) and 10.48 kPa (1.87 m/s), respectively, with corresponding sensitivity of 79.1%, 93.3%, and 100%; specificity of 80.0%, 70.8% and 71.8%. The AUCs of LSMs in identifying fibrosis ≥ stage 2, ≥ stage 3 and stage 4 (0.82, 0.87, and 0.91, respectively) were significantly higher than that of APRI (0.67, 0.64, and 0.72, respectively) and FIB-4 (0.70, 0.68, and 0.75, respectively) (all P<0.05). CONCLUSIONS: LSM obtained by STE exhibited its good capability to evaluate liver fibrosis stages in patients with AILD. As a noninvasive modality for liver fibrosis staging, STE is superior to APRI and FIB-4 biomarker scores.

How does liver steatosis affect diagnostic performance of 2D-SWE.SSI: assessment from aspects of steatosis degree and pathological types.

OBJECTIVE: Two-dimensional shear wave elastography performed by SurperSonics (2D-SWE.SSI) performs well in evaluating liver fibrosis. Steatosis is one of confounding factors which might decrease accuracy, and its effect on 2D-SWE.SSI is still controversial. Our purpose is to evaluate the diagnostic performance of 2D-SWE.SSI affected by different steatosis stages and pathological types in chronic hepatitis B (CHB) patients. METHODS: 2D-SWE.SSI was performed on 1306 CHB patients. All patients were divided into mild steatosis, moderate to severe steatosis, and non-steatosis groups. Subgroup analysis was performed according to pathological type. Liver biopsy was reference standard. Propensity score matching was performed to adjust for differences in patient characteristics. The median values of different steatosis group were compared by non-parametric tests before and after propensity score matching. The area under the receiver operating characteristic curve (AUC) was analyzed to assess the diagnostic performance in different steatosis groups. RESULTS: The median values were not significantly different in different steatosis degrees expected in F0-1 patients. The AUC of 2D-SWE.SSI was not affected by different stages of liver steatosis for cirrhosis (= F4) (0.896, 0.853, 0.929, p = 0.34). The high AUCs (0.847, 0.856) were achieved in the non-steatosis and mild steatosis groups, and all were significantly higher than those of the moderate to severe steatosis group for ≥ F2. Moreover, the panacinar type had the best AUC (0.980 for F4 and 0.930 for ≥ F2). CONCLUSION: In conclusion, moderate to severe steatosis affects 2D-SWE.SSI in CHB patients. These patients had high LSM values in patients with F0-1 and lower accuracy in ≥ F2. Patients with panacinar steatosis have the highest overall diagnostic performance. KEY POINTS: • 2D-SWE.SSI was widely used in evaluating liver fibrosis and it has many confounding factors. Steatosis is one of the confounding factors and its effect on 2D-SWE.SSI was controversial. • Our study based on 1306 CHB patients with liver biopsy found that 2D-SWE.SSI might be affected by moderate to severe liver steatosis in diagnostically significant fibrosis (≥ F2) of CHB patients. • Patients with steatosis of the panacinar type have the highest overall diagnostic performance.

Noninvasive assessment of liver fibrosis in chronic hepatitis B carriers with sound touch elastography: study of surgical pathology specimens.

PURPOSE: To evaluate the diagnostic performance of sound touch elastography (STE) for staging liver fibrosis in chronic hepatitis B (CHB) patients using pathological stage of surgical specimens as the reference standard. METHOD: 239 CHB patients were included. Liver stiffness measurements (LSMs) on STE and Supersonic shear imaging (SSI), gamma glutamyl transferase-to-platelet ratio (GPR), aspartate aminotransferase-to-platelet ratio index (APRI) and four-factor Fibrosis-4 (FIB-4) index were obtained. Areas under the receiver operating characteristic (ROC) curves (AUCs) for the diagnosis of fibrosis stage were calculated and compared. RESULTS: The LSMs obtained by STE and SSI significantly correlated with the fibrosis stages (r = 0.757; r = 0.758, respectively, both p < 0.001). No significant differences in AUCs were observed between STE and SSI in identifying fibrosis ≥stage 1 (0.92 vs. 0.94), ≥stage 2 (0.89 vs. 0.91), ≥stage 3 (0.90 vs. 0.91) or stage 4 (0.92 vs. 0.91). Both STE and SSI had significantly higher AUCs in identifying each fibrosis stage than the GPR (0.68, 0.77, 0.76 and 0.79), APRI (0.53, 0.66, 0.74 and 0.69) and FIB-4 (0.61, 0.77, 0.79 and 0.74). CONCLUSIONS: STE is an efficient tool for assessing liver fibrosis in CHB patients, with performance comparable to that of SSI and superior to that of biomarkers.

Quantitative Inflammation Assessment for Crohn Disease Using Ultrasensitive Ultrasound Microvessel Imaging: A Pilot Study.

OBJECTIVES: Crohn disease (CD) is a chronic inflammation in the digestive tract that affects millions of Americans. Bowel vascularity has important diagnostic information because inflammation is associated with blood flow changes. We recently developed an ultrasensitive ultrasound microvessel imaging (UMI) technique with high vessel sensitivity. This study aimed to evaluate the feasibility of UMI to assist CD detection and staging. METHODS: Ultrasound microvessel imaging was performed on 76 bowel wall segments from 48 symptomatic patients with CD. Clinically indicated computed tomographic/magnetic resonance enterography was used as the reference standard. The vessel-length ratio (VLR, the number of vessel pixels in the bowel wall segment normalized to the segment length) was derived in both conventional color flow imaging (CFI) and UMI to quantitatively stage disease activity. Receiver operating characteristic curves were then analyzed between different disease groups. RESULTS: The VLR-CFI and VLR-UMI detected similar correlations between vascularization and disease activity: severe inflammation had a higher VLR than normal/mildly inflamed bowels (P < .05). No significant difference was found between quiescent and mild CD due to the small sample size. The VLR-CFI had more difficulties in distinguishing quiescent versus mild CD compared to the VLR-UMI. After combining the VLR-UMI with thickness, in the receiver operating characteristic curve analysis, the areas under the curves (AUCs) improved to AUC1 = 0.996 for active versus quiescent CD, AUC2 = 0.978 for quiescent versus mild CD, and AUC3 = 0.931 for mild versus severe CD, respectively, compared to those using thickness alone (AUC1 = 0.968; P = .04; AUC2 = 0.919; P = .16; AUC3 = 0.857; P = .01). CONCLUSIONS: Ultrasound microvessel imaging offers a safe and cost-effective tool for CD diagnosis and staging, which may potentially assist disease activity classification and therapy efficacy evaluation.

Pediatric Cardiac Shear Wave Elastography for Quantitative Assessment of Myocardial Stiffness: A Pilot Study in Healthy Controls.

The long-term goal of this study is to assess chemotherapy-induced cardiotoxicity for pediatric cancer patients using cardiac ultrasound shear wave (SW) elastography. This pilot study aimed to systematically investigate the feasibility of using cardiac SW elastography in children and provide myocardial stiffness control data for cancer patients. Twenty healthy volunteers (ages 5-18) were recruited. A novel cardiac SW elastography sequence with pulse-inversion harmonic imaging and time-aligned sequential tracking was developed for this study. Cardiac SW elastography produces and detects transient SWs propagating in the myocardium in late-diastole, which can be used to quantify myocardial stiffness. The parasternal long-axis (L-A) and short-axis (S-A) views of the interventricular septum (IVS) were feasible for pediatric cardiac SW elastography. The L-A and S-A views of the basal and mid IVS provided better success rates than those of the apical IVS. Success rates decreased with increased body mass index (BMI), but did not differ with age or gender. Two-dimensional SW speed measurements were 1.26, 1.22, 1.71 and 1.67 m/s for L-A base, L-A mid, S-A base and S-A mid IVS, respectively. All S-A SW speed values were significantly higher (p < 0.01) than L-A values due to myocardial anisotropy. No SW speed difference was observed for different ages and genders. This pilot study demonstrated, for the first time, the feasibility of using cardiac SW elastography to measure quantitative myocardial stiffness in children, and established control SW speed values for using SW elastography to assess chemo-induced cardiotoxicity for pediatric cancer patients. The results showed that the myocardial anisotropy needs to be accounted for when comparing SW speed from different imaging axes.

Quantitative Assessment of Left Ventricular Diastolic Stiffness Using Cardiac Shear Wave Elastography: A Pilot Study.

OBJECTIVES: The purpose of this study was to systematically investigate the feasible echocardiographic views for human transthoracic cardiac shear wave elastography (SWE) and the impact of myocardial anisotropy on myocardial stiffness measurements. METHODS: A novel cardiac SWE technique using pulse inversion harmonic imaging and time-aligned sequential tracking was developed for this study. The technique can measure the quantitative local myocardial stiffness noninvasively. Ten healthy volunteers were recruited and scanned by the proposed technique 3 times on 3 different days. RESULTS: Seven combinations of echocardiographic views and left ventricular (LV) segments were found to be feasible for LV diastolic stiffness measurements: basal interventricular septum under parasternal short- and long-axis views; mid interventricular septum under parasternal short- and long-axis views; anterior LV free wall under parasternal short- and long-axis views; and posterior LV free wall under a parasternal short-axis view. Statistical analyses showed good repeatability of LV diastolic stiffness measurements among 3 different days from 70% of the participants for the basal interventricular septum and posterior LV free wall short-axis views. On the same LV segment, the mean diastolic shear wave speed measurements from the short-axis view were statistically different from the long-axis measurements: 1.82 versus 1.29 m/s for the basal interventricular septum; 1.81 versus 1.45 m/s for mid interventricular septum; and 1.96 versus 1.77 m/s for the anterior LV free wall, indicating that myocardial anisotropy plays a substantial role in LV diastolic stiffness measurements. CONCLUSIONS: These results establish the preliminary normal range of LV diastolic stiffness under different scan views and provide important guidance for future clinical studies using cardiac SWE.

Quantitative assessment of rotator cuff muscle elasticity: Reliability and feasibility of shear wave elastography.

Ultrasound imaging has been used to evaluate various shoulder pathologies, whereas, quantification of the rotator cuff muscle stiffness using shear wave elastography (SWE) has not been verified. The purpose of this study was to investigate the reliability and feasibility of SWE measurements for the quantification of supraspinatus (SSP) muscle elasticity. Thirty cadaveric shoulders (18 intact and 12 with torn rotator cuff) were used. Intra- and inter-observer reliability was evaluated on an established SWE technique for measuring the SSP muscle elasticity. To assess the effect of overlying soft tissues above the SSP muscle, SWE values were measured with the transducer placed on the skin, on the subcutaneous fat after removing the skin, on the trapezius muscle after removing the subcutaneous fat, and directly on the SSP muscle. In addition, SWE measurements on 4 shoulder positions (0°, 30°, 60°, and 90° abduction) were compared in those with/without rotator cuff tears. Intra- and inter-observer reliability of SWE measurements were excellent for all regions in SSP muscle. Also, removing the overlying soft tissue showed no significant difference on SWE values measured in the SSP muscle. The SSP muscle with 0° abduction showed large SWE values, whereas, shoulders with large-massive tear showed smaller variation throughout the adduction-abduction positions. SWE is a reliable and feasible tool for quantitatively assessing the SSP muscle elasticity. This study also presented SWE measurements on the SSP muscle under various shoulder abduction positions which might help characterize patterns in accordance to the size of rotator cuff tears.

Feasibility assessment of shear wave elastography to rotator cuff muscle.

Pre-surgical measurement of supraspinatus muscle extensibility is important for rotator cuff repair. The purpose of the present study was to explore the potential feasibility of a shear wave ultrasound elastography (SWE)-based method, combined with B-mode ultrasound, to measure the in vivo stiffness of the supraspinatus muscle non-invasively and thus obtain key information about supraspinatus muscle extensibility. Our investigation comprised two steps. First, we determined the orientation of the supraspinatus muscle fibers in cadaveric shoulders without rotator cuff tear in order to optimize the ultrasound probe positions for SWE imaging. Second, we investigated the feasibility of quantifying the stiffness of the normal supraspinatus muscle by SWE in vivo. The supraspinatus muscle was divided into four anatomical regions: anterior superficial (AS), posterior superficial (PS), anterior deep (AD), and posterior deep (PD). Each region was examined by SWE. The SWE stiffnesses of AD, AS, PD, and PS were 40.0 ± 12.4, 34.0 ± 9.9, 32.7 ± 12.7, 39.1 ± 15.7 kPa, respectively. SWE combined with B-Mode ultrasound imaging could be a feasible method for quantifying the local stiffness of the rotator cuff muscles.

Noninvasive assessment of liver fibrosis using ultrasound-based shear wave measurement and comparison to magnetic resonance elastography.

OBJECTIVES: Magnetic resonance elastography (MRE) has excellent performance in detecting liver fibrosis and is becoming an alternative to liver biopsy in clinical practice. Ultrasound techniques based on measuring the propagation speed of the shear waves induced by acoustic radiation force also have shown promising results for liver fibrosis staging. The objective of this study was to compare ultrasound-based shear wave measurement to MRE. METHODS: In this study, 50 patients (28 female and 22 male; age range, 19-81 years) undergoing liver MRE examinations were studied with an ultrasound scanner modified with shear wave measurement functionality. For each patient, 27 shear wave speed measurements were obtained at various locations in the liver parenchyma away from major vessels. The median shear wave speed from all measurements was used to calculate a representative shear modulus (µ) for each patient. Magnetic resonance elastographic data processing was done by a single analyst blinded to the ultrasound measurement results. RESULTS: Ultrasound and MRE measurements were correlated (r = 0.86; P < .001). Receiver operating characteristic (ROC) analysis was applied to the ultrasound measurement results with the MRE diagnosis as the "ground truth." The area under the ROC curve for separating patients with minimum fibrosis (defined as µ(MRE) ≤2.9 kPa) was 0.89 (95% confidence interval, 0.77-0.95), and the area under the ROC curve for separating patients with advanced fibrosis (defined as µ(MRE) ≥5.0 kPa) was 0.96 (95% confidence interval, 0.87-0.99). CONCLUSIONS: Results indicate that the ultrasound-based shear wave measurement correlates with MRE and is a promising method for liver fibrosis staging.

Assessment of liver viscoelasticity by using shear waves induced by ultrasound radiation force.

PURPOSE: To investigate the value of viscosity measured with ultrasonographic (US) elastography in liver fibrosis staging and to determine whether the use of a viscoelastic model to estimate liver elasticity can improve its accuracy in fibrosis staging. MATERIALS AND METHODS: The study, which was performed from February 2010 to March 2011, was compliant with HIPAA and approved by the institutional review board. Written informed consent was obtained from each subject. Ten healthy volunteers (eight women and two men aged 27-55 years) and 35 patients with liver disease (17 women and 18 men aged 19-74 years) were studied by using US elasticity measurements of the liver (within 6 months of liver biopsy). US data were analyzed with the shear wave dispersion ultrasound vibrometry (SDUV) method, in which elasticity and viscosity are measured by evaluating dispersion of shear wave propagation speed, as well as with the time-to-peak (TTP) method, where tissue viscosity was neglected and only elasticity was estimated from the effective shear wave speed. The hepatic fibrosis stage was assessed histologically by using the METAVIR scoring system. The correlation of elasticity and viscosity was assessed with the Pearson correlation coefficient. The performances of SDUV and TTP were evaluated with receiver operating characteristic (ROC) curve analysis. RESULTS: The authors found significant correlations between elasticity and viscosity measured with SDUV (r = 0.80) and elasticity measured with SDUV and TTP (r = 0.94). The area under the ROC curve for differentiating between grade F0-F1 fibrosis and grade F2-F4 fibrosis was 0.98 for elasticity measured with SDUV, 0.86 for viscosity measured with SDUV, and 0.95 for elasticity measured with TTP. CONCLUSION: The results suggest that elasticity and viscosity measured between 95 Hz and 380 Hz by using SDUV are correlated and that elasticity measurements from SDUV and TTP showed substantially similar performance in liver fibrosis staging, although elasticity calculated from SDUV provided a better area under the ROC curve.

Preliminary assessment of one-dimensional MR elastography for use in monitoring focused ultrasound therapy.

The purpose of this work is to assess a fast technique that measures tissue stiffness and temperature during focused ultrasound thermal therapy (FUS). A one-dimensional (1D) MR elastography (MRE) pulse sequence was evaluated for the purpose of obtaining rapid measurements of thermally induced changes in tissue stiffness and temperature for monitoring FUS treatments. The accuracy of the 1D measurement was studied by comparing tissue displacements measured by 1D MRE with those measured by the well-established 2D MRE pulse sequence. The reproducibility of the 1D MRE measurement was assessed, in gel phantoms and ex vivo porcine tissue, for varied FUS intensity levels (31.5-199.9 W cm(-2)) and over a range of displacements at the focus (0.1-1 microm). Temperature elevations in agarose gel phantoms were measured using 1D MRE and calibrated using fiberoptic-thermometer-based measurements. The 1D MRE displacement measurements are highly correlated with those obtained with the 2D technique (R(2) = 0.88-0.93), indicating that 1D MRE can successfully measure tissue displacement. Ten repeated trials at each FUS power level yielded a minimum detectable displacement change of 0.2 microm in phantoms and 0.4 microm in tissue (at 95% confidence level). The 1D MRE temperature measurements correlated well with temperature changes measured simultaneously with fiberoptic thermometers (R(2) = 0.97). The 1D MRE technique is capable of detecting tissue displacements as low as 0.4 microm, which is an order of magnitude smaller than 5 microm displacements expected during FUS therapy (Le et al 2005 AIP Conf. Proc.: Ther. Ultrasound 829 186-90). Additionally, 1D MRE was shown to provide adequate measurements of temperature elevations in tissue. These findings indicate that 1D MRE may be an effective tool for monitoring FUS treatments.

[Sustainable rice pest management and its economic benefits].

With rice varieties Jiahua 1 (resistant to the white backed plant hopper Sogatella furcifera) and Shanyou 63 (susceptible) as test materials, this paper studied the effects of different insecticide treatments on the pest population and quality and yield of rice grain, and evaluated their actual economic benefits (AEB). The results indicated that in the control plot, the peak density of S. furcifera on Jiahua 1 was only 1/10 of that on Shanyou 63. Throughout the whole rice growth period, the S. furcifera population on Jiahua 1 kept below economic injury level, while Shanyou 63 suffered heavy infestation by S. furcifera. The spider density in the control plot was 3 -7 times higher than that in the plots treated with insecticide following farmers' practice. No application of insecticide decreased the grain yield of Jiahua 1 and Shanyou 63 by 11. 8% and 43.4% , respectively. Compared with the control, spraying with insecticide one time decreased the AEB of Jiahua 1 and Shanyou 63 by 0.9% - 2.6% and 2.6% - 4.7% , respectively. Without insecticide application, the AEB of Shanyou 63 decreased by 32.9% - 36.1% , while that of Jiahua 1 increased by 2.2% - 4.8%. The income of planting Jiahua 1 without insecticide application was 9403 yuan x hm(-2) , which was remarkably higher than that (8632 yuan hm (-2)) of Shanyou 63 protected by spraying insecticide 3 times. It was worthwhile to point out that insecticide treatment did not affect the processing of rice grain and its commercial and edible quality, but decreased its protein content of Jiahua 1 and Shanyou 63.