Near Crack Line Elastic-Plastic Analysis for an Infinite Plate Loaded by a Pair of Point Shear Forces

The near crack line analysis method was used to investigate a crack loaded by a pair of point shear forces in an infinite plate in an elastic-perfectly plastic solid. The analytical solution was obtained, that is the elastic-plastic fields near crack line and law that the length of the plastic zone along the crack line is varied with external loads. The results are sufficiently precise near the crack line and are not confined by small scale yielding conditions.

Comparison of point and two-dimensional shear wave elastography of the spleen in healthy subjects

BACKGROUND Few systematic comparative studies of the different methods of physical elastography of the spleen are currently available.AIM To compare point shear wave and two-dimensional elastography of the spleen considering the anatomical location(upper,hilar,and lower pole).METHODS As part of a prospective clinical study,healthy volunteers were examined for splenic elasticity using four different ultrasound devices between May 2015 and April 2017.The devices used for point shear wave elastography were from Siemens(S 3000)and Philips(Epiq 7),and those used for two-dimensional shear wave elastography were from GE(Logiq E9)and Toshiba(Aplio 500).In addition,two different software versions(5.0 and 6.0)were evaluated for the Toshiba ultrasound device(Aplio 500).The study consisted of three arms:A,B,and C.RESULTS In study arm A,200 subjects were evaluated(78 males and 122 females,mean age 27.9±8.1 years).In study arm B,113 subjects were evaluated(38 men and 75 women,mean age 26.0±6.3 years).In study arm C,44 subjects were enrolled.A significant correlation of the shear wave velocities at the upper third of the spleen(r=0.33088,P<0.0001)was demonstrated only for the Philips Epiq 7 device compared to the Siemens Acuson S 3000.In comparisons of the other ultrasound devices(GE,Siemens,Toshiba),no comparable results could be obtained for any anatomical position of the spleen.The influencing factors age,gender,and body mass index did not show a clear correlation with the measured shear wave velocities.CONCLUSION The absolute values of the shear wave elastography measurements of the spleen and the two different elastography methods are not comparable between different manufacturers or models.

Liver stiffness as a predictor of hepatocellular carcinoma behavior in patients with hepatitis C related liver cirrhosis

Background: Risk strati cation and prognostication of hepatocellular carcinoma (HCC) help to improve patient outcome. Herein we investigated the role of liver stiffness measurement (LSM) in the prediction of HCC behavior. Methods: Totally 121 na ve patients with HCC were included. HCC radiological evaluation and staging were done. LSM was measured using virtual touch quanti cation. Patients were divided into early to intermediate HCC (BCLC-0, A and B) and late HCC (BCLCC and D). HCC was treated according to the BCLC stage. HCC recurrence-free interval was estimated. Results: The mean LSM inside the tumor was signi cantly lower than the peri-tumoral area and the cirrhotic non-cancerous liver parts (P<0.001). In late HCCs stage, the mean LSM inside the tumor and in the peri-tumoral tissue was lower than the corresponding values in the early to intermediate HCCs stage (P<0.001). LSM inside the tumor and in the peri-tumoral tissue negatively correlated with serum AFP, tumor vascular invasion, and stage (P<0.05). The recurrence-free interval was directly correlated to LSM inside the tumor and inversely to LSM in cirrhotic non tumorous liver part. Kaplan-Meier analysis showed that the recurrence-free interval was signi cantly longer in patients with LSM inside the tumor of ≥1.25m/s compared to those with LSM inside the tumor of<1.25m/s. Conclusions: LSM can serve as a potential non-invasive predictor for HCC clinical behavior and the recurrence-free interval following loco-regional treatments.

Non-invasive splenic parameters of portal hypertension:Assessment and utility

BACKGROUND Portal hypertension is a major complication of cirrhosis that is associated with significant morbidity and mortality.The present gold-standard method to risk stratify and observe cirrhosis patients with portal hypertension is hepatic venous pressure gradient measurement or esophagogastroduodenoscopy.However,these methods are invasive,carry a risk of complications and are associated with significant patient discomfort.Therefore,non-invasive splenic parameters are of clinical interest as potential useful markers in determining the presence of portal hypertension.However,diagnostic accuracy and reproducibility remains unvalidated.AIM To assess the diagnostic accuracy of spleen stiffness,area and diameter in predicting the presence of portal hypertension.METHODS Of 50 patients with varying liver disease pathologies were prospectively recruited from the St.Mary’s Hospital Liver Unit in London;25 with evidence of portal hypertension and 25 with no evidence of portal hypertension.Liver stiffness,spleen stiffness,spleen diameter and spleen area were measured using the Philips Affiniti 70 elastography point quantification point shear wave elastography system.The aspartate aminotransferase-to-platelet-ratio-index(APRI)score was also calculated.Performance measures,univariate and multivariate logistic regression were used to evaluate demographic,clinical and elastography variables.Interclass correlation coefficient was used to determine the reproducibility of splenic area and diameter.RESULTS On univariate and individual performance,platelet count[area under the receiver operating characteristic(AUROC)0.846,P value<0.001],spleen area(AUROC 0.828,P value=0.002)and APRI score(AUROC 0.827,P value<0.001)were the most accurate variables in identifying the presence of portal hypertension.On multivariate logistic regression models constructed,the combination of spleen area greater than 57.90 cm2 and platelet count less than 126×10^9 had 63.2%sensitivity and 100%specificity,100%positive predictive value and 100%negative predictive value.An alternative combination of spleen stiffness greater than 29.99 kPa and platelet count less than 126×10^9 had 88%sensitivity,75%specificity,78.6%positive predictive value and 85.7%negative predictive value.An interclass correlation coefficient value of 0.98(95%CI:0.94-0.99,P value<0.001)and 0.96(95%CI:0.91-0.99,P value<0.001)were determined for inter-operator variability for spleen area and diameter respectively.CONCLUSION Spleen area,spleen stiffness and platelet count may be useful markers to assess the presence of portal hypertension in patients of various etiologies.