Acoustic radiation force impulse (ARFI) elastography of the bowel wall as a possible marker of inflammatory activity in patients with Crohn's disease.

AIM: To evaluate acoustic radiation force impulse (ARFI) shear-wave velocities of the bowel wall in patients with Crohn's disease (CD). MATERIAL AND METHODS: ARFI shear-wave elastography was analysed within the wall of the stomach, terminal ileum, and sigmoid, and correlated with ultrasound signs of activity in CD patients both retrospectively and in a prospective cohort. RESULTS: A total of 77 retrospective and 21 prospective CD patients were included. ARFI elastography in the stomach, the normal ileum, and sigmoid was lower than in ileitis or sigmoiditis. Retrospectively, the ARFI values correlated with the bowel wall thickness and Limberg vascularisation score. Prospectively, there was no correlation between ARFI and bowel wall thickness, Limberg score, clinical activity, or C-reactive protein. A cut-off analysis of 105 ileal ARFI measurements showed a cut-off value of 1.92 m/s for the diagnosis of ileal inflammation with 75.3% sensitivity and 87.5% specificity. CONCLUSION: In patients with CD, ARFI shear-wave velocities show a trend to higher values in inflamed bowel wall thickening on B-mode ultrasound; however, the differences appear small and may not be clinically significant. The factors influencing ARFI measurements of the bowel wall require further investigation.

LI-RADS-CEUS - Proposal for a Contrast-Enhanced Ultrasound Algorithm for the Diagnosis of Hepatocellular Carcinoma in High-Risk Populations.

Purpose: To develop a contrast-enhanced ultrasound algorithm (LI-RADS-CEUS = liver imaging reporting and data system with contrast-enhanced ultrasound) for the diagnosis of hepatocellular carcinoma (HCC) in patients at risk. Materials and Methods: A CEUS algorithm (LI-RADS-CEUS) was designed analogously to CT- and MRI-based LI-RADS. LI-RADS-CEUS was evaluated retrospectively in 50 patients at risk with confirmed HCC or non-HCC lesions (test group) with subsequent validation in a prospective cohort of 50 patients (validation group). Results were compared to histology, CE-CT and CE-MRI as reference standards. Results: Tumor diagnosis in the test group/validation group (n = 50/50) were 46/41 HCCs, 3/3 intrahepatic cholangiocellular carcinomas (ICCs) and 1/6 benign lesions. The diagnostic accuracy of LI-RADS-CEUS for HCC, ICC and non-HCC-non-ICC-lesions was 89 %. For the diagnosis of HCC, the diagnostic accuracy was 93.5 % (43/46 cases) in the test group and 95.1 % (39/41 cases) in the validation group. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 94.3 %, 66.6 %, 94.3 % and 66.6 %, respectively (mean values from both cohorts). Histological findings of HCC were available in 40 versus 23 cases (in total: G1 / G2/G3: 15/35/13). Arterial hyperenhancement was seen in 68/87 (78.2 %) of HCCs. Arterial hyperenhancement with subsequent portal venous or late phase hypoenhancement was seen in 66 % of HCCs. Conclusion: LI-RADS-CEUS offers a CEUS algorithm for standardized assessment and reporting of focal liver lesions in patients at risk for HCC. Arterial hyperenhancement in CEUS is the key feature for the diagnosis of HCC in patients at risk, whereas washout is not a necessary prerequisite.

Comparison of Acoustic Radiation Force Impulse (ARFI) Elastography Measurements with the 4C1 Transducer to the 6C1HD Transducer: A Phantom and Patient Study.

Purpose: The aim of this study was to evaluate whether acoustic radiation force impulse (ARFI) elastography done with the 4C1 probe yields comparable results to the recently introduced 6C1HD probe. Materials and Methods: Measurements with the 4C1 and 6C1HD probes (Acuson S2000) were performed and compared in four different inclusions of an elasticity phantom model (QA049 CIRS) as well as in the liver of healthy individuals and patients with liver cirrhosis. Results: Measurements with the 6C1HD probe were slightly higher in all phantom inclusions (8, 14, 45, 80kPA) with a mean of 1.48 m/s (95 %-CI; 1.47 - 1.49), 2.18 m/s (95 %-CI; 2.17 - 2.19), 3.61 m/s (95 %-CI; 3.57 - 3.64) and 4.34 m/s (95 %-CI; 4.29 - 4.39) compared to the 4C1 transducer with 1.46 m/s (95 %-CI; 1.45 - 1.47), 2.15 m/s (95 %-CI; 2.14 - 2.16), 3.39 m/s (95 %-CI; 3.37 - 3.41) and 3.98 m/s (95 %-CI; 3.75 - 4.21), respectively (p = 0.04, p < 0.01, p < 0.01, p < 0.01). Cirrhotic patients (n = 40) had a higher mean shear wave speed with 3.00 m/s (95 %-CI; 2.80 - 3.21) with the 6C1HD transducer compared to 2.81 m/s (95 %-CI; 2.64 - 2.99) with the 4C1 transducer (p = 0.03). Healthy individuals (n = 20) had a mean shear wave speed of 1.12 m/s (95 %-CI; 1.06 - 1.17) with the 6C1HD probe and 1.12 m/s (95 %-CI; 1.05 - 1.19) with the 4C1 probe (p = 0.96). Conclusion: ARFI values assessed with a 6C1HD transducer are slightly higher than measurements with a 4C1 transducer in an ARFI phantom and in patients with liver cirrhosis. As the difference is small, current cut-off values keep their usefulness but should be interpreted with caution if measurements are close to the cut-off.

[Ultrasound elastography]. / Ultraschallelastographie.

Noninvasive, ultrasound-based methods for visualizing and measuring tissue elasticity are becoming more and more common in routine practice. Using hepatic shear wave elastography, cut-off levels can help to detect the degree of relevant fibrosis (F ≥ 2) with a diagnostic accuracy using the area under the reader operating characteristic (AUROC) of 87 % and cirrhosis (F = 4, AUROC 93 %). Normal values virtually exclude liver cirrhosis (negative predictive value up to 97 %) and high shear wave velocities predict complications in the course of primary sclerosing cholangitis, liver cirrhosis and chronic hepatitis B or C. Elastography is of no relevant help in the differentiation of the dignity of hepatic lesions. Concerning thyroid or breast lesions, low shear wave velocities are indicative of benign lesions and in contrast, high velocities of malignant lesions. A differentiation between benign and malignant thyroid nodules is performed by elastography with a sensitivity of 89 % and a specificity of 82 %. In breast lesions a differentiation of nodes can be improved with elastography compared to B-mode ultrasound alone with a sensitivity of 97 % and a specificity of 83 %. Invasive biopsy punctures can therefore be specifically performed or can be omitted. Due to several influencing factors, in particular during liver elastography, the measurements need to be interpreted in the clinical context. In summary, ultrasound-based elastography provides helpful information for the detection of hepatic fibrosis and for further characterization of thyroid or breast lesions in addition to classical techniques, such as B-mode imaging and color Doppler.

Quantitative perfusion analysis in pancreatic contrast enhanced ultrasound (DCE-US): a promising tool for the differentiation between autoimmune pancreatitis and pancreatic cancer.

In the work-up of focal pancreatic lesions autoimmune pancreatitis (AIP) is a rare differential diagnosis to pancreatic cancer (PC) with similar clinical constellations. The aim of our study was to compare differences between proven AIP and PC using transabdominal dynamic contrast enhanced ultrasound (DCE-US). Therefore we recorded 3-minute-clips of CEUS examinations and analyzed perfusion parameters with VueBox®-quantification software. To obtain DCE-US Parameters, Regions-of-Interest were selected within the lesions and the surrounding pancreas parenchyma, serving as reference tissue. We compared 3 patients with AIP (mean age: 58 years; lesion mean size: 40 mm) to 17 patients with PC (mean age: 68 years; lesion mean size: 35.9 mm). Significant differences between PC and parenchyma could be found in the following parameters: Peak-Enhancement (PE), Wash-in-and-Wash-out-AUC, Wash-in Perfusion-Index. PE of AIP was comparable to normal parenchyma. The relation of PE between parenchyma and lesion (ΔPE) AIP and PC was significantly different [AIP: 0.21 (±0.06); PC: 0.81 (±0.1); p<0.01]. PE of neoplastic lesions was significantly lower as AIP and normal parenchyma (p<0.01). Therefore perfusion analysis in DCE-US can help to differentiate hypovascular PC from AIP presenting nearly isovascular time intensity curves. Diagnostic accuracy of DCE-US in this setting has to be validated in future prospective studies in comparison to CT and MRI.

Dynamic contrast-enhanced ultrasound (DCE-US) for the characterization of hepatocellular carcinoma and cholangiocellular carcinoma.

PURPOSE: In a prospective study, we compared the different perfusion kinetics of HCC and ICC using dynamic contrast-enhanced ultrasound (DCE-US). MATERIALS AND METHODS: Patients with proven HCC and ICC were included. Three-minute video clips of CEUS examinations (CPS - low MI mode) after a bolus injection of 1.2 ml SonoVue were recorded and analyzed with quantification software (VueBox). Parameters for the arterial contrast enhancement [rise time (RT), time-to-peak (TTP)] towards portal venous contrast enhancement [mean transit time (local) (mTTl) and fall time (FT)] were quantified. Furthermore, contrast wash-out after peak enhancement (PE) (40 s, 80 s, 100 s and 120 s after PE) was compared between HCC and ICC. RESULTS: 43 patients with proven HCC (n = 23 HCC; cirrhosis n = 16) and ICC (n = 20 ICC; Cirrhosis n = 6) were examined. No statistical difference of the arterial DCEUS parameters was found between HCC and ICC. Contrast enhancement of the portal venous and late phases showed significantly lower values in the ICC group indicating early wash-out of the contrast agent: mTTl (p = 0.0209): HCC 118.4 s (SD±â€Š88.4); ICC 64.8 s (SD±â€Š49.7). FT (p = 0.0433): HCC 42.5 s (SD±â€Š27.7); ICC 27.7 s (SD±â€Š16.2). The percental loss of intensity at a definite time point after PE was significantly higher in ICC than in HCC lesions. CONCLUSION: DCE-US is able to detect and quantify differences in perfusion kinetics between HCC and ICC. Whereas arterial contrast enhancement patterns may overlap between HCC and ICC, a timed characterization of wash-out kinetics may offer an additional tool to characterize HCC and ICC. The presence of a rapid loss of signal intensity in the early portal venous phase is significantly higher in ICC than in HCC lesions.

Acoustic radiation force impulse (ARFI) and high-frequency ultrasound of the liver surface for the diagnosis of compensated liver cirrhosis.

PURPOSE: To evaluate the diagnostic value of acoustic radiation force impulse (ARFI) and high-frequency ultrasound of the liver surface, using histology as a gold standard for the diagnosis of compensated liver cirrhosis. MATERIALS AND METHODS: 73 patients without ascites undergoing liver biopsy were included in the study. The left and right liver lobes were examined with ARFI and high-frequency ultrasound. Liver surface irregularity was quantified using image analysis software to calculate the difference between the real surface and the approximated physiological surface through a 20 mm standardized line. RESULTS: There is a significant difference between cirrhotic and non-cirrhotic patients for both quantified liver surface (QLS) and ARFI (p < 0.001). The mean values for QLS of the left lobe were 0.71 ± 0.24 mm and 1.17 ±â€Š0.80 mm, of the right lobe 0.56 ±â€Š0.26 mm and 0.87 ±â€Š0.26 mm for non-cirrhotic and cirrhotic patients, respectively. The mean values of ARFI measurements of the left lobe were 2.04 ±â€Š0.76 m/s and 2.85 ±â€Š0.81 m/s, of the right lobe 1.65 ±â€Š0.61 m/s and 3.02 ±â€Š0.77 m/s for non-cirrhotic and cirrhotic patients, respectively. Diagnostic accuracy (AUROC) was 0.78/0.80 for QLS and 0.77/0.91 for ARFI of the left/right lobe, respectively. ARFI of the right lobe is significantly better than ARFI of the left (p = 0.023) or QLS of the left (p = 0.025)/right (p = 0.046) lobe of the liver. CONCLUSION: Assessment of liver surface irregularity by high-frequency ultrasound (QLS) is a useful diagnostic test for the assessment of compensated liver cirrhosis. ARFI of the right liver lobe is significantly better than high-frequency ultrasound (QLS of the left/right lobe of the liver) and ARFI of the left lobe of the liver.

Outcome analysis of liver stiffness by ARFI (acoustic radiation force impulse) elastometry in patients with chronic viral hepatitis B and C.

AIM: To evaluate the association between liver stiffness measured by acoustic radiation force impulse (ARFI) elastometry and the outcome of antiviral treatment in patients with chronic viral hepatitis B and C. MATERIALS AND METHODS: Thirty-eight patients with chronic viral hepatitis B (n = 16) or hepatitis C (n = 22) underwent liver biopsy and ARFI elastometry of the right hepatic lobe. A follow-up assessment using ARFI was performed a mean of 2.3 years after the baseline evaluation. The patients with favourable outcome were classified in group S and those receiving no treatment, showing no response to treatment, or experiencing a relapse were classified in group N. RESULTS: The 38 patients had an initial mean ARFI value of 1.56 ± 0.62 m/s as compared with 1.54 ± 0.64 m/s in the follow-up evaluation. Group S showed a significant decline in ARFI values (1.55 ± 0.60 m/s versus 1.34 ± 0.47 m/s; p < 0.05) and included 16 (64%) patients with lower shear wave velocities at follow-up. In group N, liver stiffness values showed a slight but not significant increase (1.57 ± 0.70 m/s versus 1.93 ± 0.77 m/s). CONCLUSION: Changes in liver stiffness during antiviral therapy can be assessed by ARFI reflecting response or no response. ARFI elastometry is an additional, useful tool for the follow-up assessment of treatment outcome in patients with chronic viral hepatitis B or C infection.

Food restriction increases glutamate receptor-mediated burst firing of dopamine neurons.

Restriction of food intake increases the acquisition of drug abuse behavior and enhances the reinforcing efficacy of those drugs. However, the neurophysiological mechanisms responsible for the interactions between feeding state and drug use are largely unknown. Here we show that chronic mild food restriction increases the burst firing of dopamine neurons in the substantia nigra. Dopamine neurons from food-restricted mice exhibited increased burst firing in vivo, an effect that was enhanced by an injection of the psychomotor stimulant cocaine (10 mg/kg, i.p.). Food restriction also enhanced aspartic acid-induced burst firing of dopamine neurons in an ex vivo brain slice preparation, consistent with an adaptation occurring in the somatodendritic compartment and independent of a circuit mechanism. Enhanced burst firing persisted after 10 d of free feeding following chronic food restriction but was not observed following a single overnight fast. Whole-cell patch-clamp recordings indicated that food restriction also increased electrically evoked AMPAR/NMDAR ratios and increased D2 autoreceptor-mediated desensitization in dopamine neurons. These results identify dopamine neurons in the substantia nigra as a convergence point for the interactions between feeding state and drugs of abuse. Furthermore, increased glutamate transmission combined with decreased autoreceptor inhibition could work in concert to enhance drug efficacy in response to food restriction.

Early response to anti-tumoral treatment in hepatocellular carcinoma--can quantitative contrast-enhanced ultrasound predict outcome?

PURPOSE: In order to detect an early response to anti-angiogenic therapy, this study aims at analyzing specific effects of a sorafenib-based regime on intra-tumoral D-CEUS flow parameters of patients with HCC. MATERIALS AND METHODS: Videos of the arterial phase were captured before initiation of a therapy with sorafenib and 1 and 3 months after (n = 9). Patients receiving a non-anti-angiogenic therapy (TACE, n = 10) served as a comparison group. Cross-sectional imaging was performed at the same time points and patients were followed up for 1 year. RESULTS: In the responder group (RE), the absolute (percentage) TTP was 11.28 s ± 2.03 s (1.00) before treatment, 13.60 s ± 1.52 s (1.53 ± 0.08) after one month (p = 0.0405), and 16.17 s ± 2.35 s (1.46 ± 0.07) after three months of treatment (p = 0.0071). The TTP increased significantly in the RE group as early as 1 month after initiation of sorafenib compared to the non-responder group. There were no significant differences in the non-responder group or between the NR and the TACE group at any time point. D-CEUS values from all sorafenib-treated patients showed good accordance with RECICL (response evaluation criteria in cancer of the liver) criteria (R2 = 0.7154, p = 0.0001). CONCLUSIONS: Quantitative CEUS reveals variations of dynamic parameters of blood flow during anti-tumoral therapy in liver cancer patients. Further investigations and clinical trails have to confirm that the TTP is a promising parameter in the prediction of early response to sorafenib-based therapy.

Dynamic contrast-enhanced ultrasound (DCE-US) for easy and rapid evaluation of hepatocellular carcinoma compared to dynamic contrast-enhanced computed tomography (DCE-CT)--a pilot study.

PURPOSE: To check the feasibility of the easy quantification of tumor vascularization derived from dynamic contrast-enhanced ultrasound (DCE-US) in comparison to dynamic contrast-enhanced computed tomography (DCE-CT) in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: 19 patients with cirrhosis and histologically proven HCC prospectively underwent CEUS (SonoVue) and CT (Imeron400). Following CEUS, the software ImageJ was used for the easy quantification of the echogenicity in HCC lesions and tumor-free liver parenchyma. For DCE-CT we used the software Hepacare and created arterial enhancement fraction color maps of the whole liver and HCC lesions. RESULTS: Unifocal/multifocal HCCs were detected in 12/7 (US) and 10/9 patients (CT) and biopsied nodules were defined as a reference lesion with a median of 40 mm (US) and 42 mm (CT). CEUS showed HCC-typical hyper-/hypoenhancement in the arterial/late phase in 16/19 reference lesions, while all reference lesions showed an HCC-typical vascular pattern in CT. With DCE-US, quantitative assessment could not be performed in 3/19 patients due to respiratory motion or insufficient image quality. 13/16 reference lesions showed an HCC-typical vascular pattern. Quantitative assessment was possible with DCE-CT in all patients and all reference nodules showed HCC-typical values of the arterial enhancement fraction. There was no statistical difference between CEUS, DCE-US and DCE-CT in the quantitative assessment of contrast enhancement. CONCLUSION: The quantitative evaluation of DCE-US was feasible in HCC without a statistical difference with respect to DCE-CT. Further studies with a larger study population including small nodules ≤ 2 cm are needed to assess whether this technique is helpful in routine ultrasound.

Impact of food intake, ultrasound transducer, breathing maneuvers and body position on acoustic radiation force impulse (ARFI) elastometry of the liver.

PURPOSE: Since acoustic radiation force impulse (ARFI) elastometry is an increasingly popular method for the assessment of hepatic fibrosis and cirrhosis, we investigated factors possibly influencing hepatic elastometric measurements. MATERIALS AND METHODS: 30 healthy volunteers (17 females, 13 males) were recruited. The shear wave velocity of the right liver lobe was determined in a fasting upright and supine position and after different breathing maneuvers with the convex array (4C1) and in a supine position with the linear (9L4) ultrasound transducer. In 18 volunteers, subsequent measurements were obtained in a fasting state and 30, 60, 90 and 120 min after ingestion of a standardized breakfast. A group of 8 patients (average age: 76 years) with right heart insufficiency was also evaluated. RESULTS: In the fasting state, the ARFI shear wave velocities measured in an upright position were significantly higher than those in supine position (p< 0.0001). The supine ARFI values were significantly higher with the linear transducer than with the convex transducer (p = 0.0034). The results in deep inspiration, deep expiration and during Valsalva maneuver showed no differences. The food intake-related ARFI elastometric measurements were significantly elevated at time points 30 min (p = 0.019) and 60 min (p = 0.036) postprandial. In right heart insufficiency, the ARFI values were elevated. CONCLUSION: Hepatic ARFI elastometry is a well evaluated method. A standardized examination should include measuring in a supine position with the convex transducer (4C1) without specific breathing maneuvers. Since ARFI elastometry values increase after food intake, measurements should be performed in the fasting state, or not earlier than 2 hours postprandially. Heart dysfunction may impair ARFI accuracy.

Mesenteric transit time using contrast-enhanced ultrasound (CEUS) does not correlate with disease activity in Crohn's disease.

PURPOSE: Evaluation of mesenteric transit time (MTT) - measured by contrast-enhanced ultrasound - as a marker for inflammatory activity in Crohn's disease. MATERIALS AND METHODS: The time of maximum enhancement of the contrast agent in the superior mesenteric artery and vein was determined visually and by software analysis. The MTT was calculated as the difference between these two time points. Findings were correlated with the Harvey-Bradshaw Index (HBI) using the Pearson correlation coefficient (r). In addition, a healthy control group was evaluated both in the fasting state and 1, 2, 3 and 4 hours postprandially. RESULTS: In 20 healthy controls the mean visual MTT during fasting was 9.76 ± 2.83 sec and decreased to a minimum 1 hour after the meal (6.6 ± 2.27 sec). 45 patients with Crohn's disease (9 males, 36 females, mean age 35 years) had a mean HBI of 5.9 ± 4.7 points. The mean software-based MTT of 9.76 ± 3.7 sec was significantly higher (p = 0.034) than the mean visual MTT of 8.22 ± 3.05 sec. The two figures correlated well (r = 0.72, p < 0.001). The HBI correlated neither with the visual (r = 0.14, p = 0.371) nor with the software-based (r = 0.16, p = 0.293) MTT. CONCLUSION: The MTT decreases in the first two hours after eating. The visually assessed and the software-based MTT correlate well, however MTT does not correlate with disease activity in patients with Crohn's disease.

An abdominal and thyroid status with Acoustic Radiation Force Impulse Elastometry--a feasibility study: Acoustic Radiation Force Impulse Elastometry of human organs.

PURPOSE: Acoustic Radiation Force Impulse (ARFI) is a new method for the quantification of tissue elasticity. To date, ARFI technology has not been applied systematically to establish an abdominal and thyroid status. The aim of this prospective feasibility study was to evaluate ARFI elastometry performed on various healthy abdominal organs and the thyroid gland. MATERIAL AND METHODS: 94 patients (43 females, 51 males) with a mean age of 54 years and 20 healthy controls were enrolled in the study. A routine ultrasound examination of the abdomen was scheduled in 72, and of the thyroid in 25. ARFI elastometry was performed in liver, spleen, pancreas, prostate, kidneys and thyroid gland with the ultrasound system Acuson S2000. ARFI values are proportional to tissue elasticity. Patients with ultrasonic or anamnestic evidence of diseased organs were excluded from the analysis. ARFI measurements were compared with the aid of the t-test and correlated using Spearman's correlation coefficient. RESULTS: ARFI elastometry proved feasible and the measurements obtained in the various organs differed significantly. Among healthy organs the spleen showed the highest mean ARFI velocities, followed by the kidney, thyroid, pancreas and the prostate. The lowest ARFI values were regularly found in healthy liver. Measurements in the kidneys and the spleen showed high standard deviation. CONCLUSIONS: ARFI elastometry may describe parenchymal stiffness of various abdominal organs and the thyroid gland. Further investigations are needed to compare these baseline findings in healthy organs with those of various tumours or diseases affecting the individual organs.

Characterization of focal liver lesions (FLL) with acoustic radiation force impulse (ARFI) elastometry.

PURPOSE: The technology of acoustic radiation force impulse (ARFI) represents an innovative method for the quantification of tissue elasticity. The aim of this prospective pilot study was to evaluate the role of ARFI elastometry of focal liver lesions (FLL) and the surrounding liver parenchyma. MATERIALS AND METHODS: All patients with unclear FLL in B-mode ultrasound were assigned to ARFI elastometry (m/sec). Measurement sites were located within the FLL, in the peritumoral tissue and in hepatic segment VIII (intercostal approach). Histology and CEUS served as the reference for the characterization of the lesions. RESULTS: A total of 81 patients were enrolled, of whom 62 patients (39 females, 23 males; mean age 54 years) had FLL measurable by means of ARFI. The lesions were: 38 benign (61 %) and 24 malignant FLL (39 %). The ARFI elastometric values of the FLL differed significantly from those of the liver parenchyma (p < 0.001). Elastometry of benign lesions and of malignant tumors showed statistically comparable results (p = 0.28). The lowest ARFI values were observed in focal fatty sparing and the highest in CCC. Only focal fatty sparing and HCC showed negative differences between FLL and peritumoral tissue or liver parenchyma. In 23 % of the hepatic lesions, no reliable quantitative ARFI results were obtainable due to false, inconsistent or technically failed measurements. CONCLUSION: FLL vary in ARFI elastometry. However, high ARFI values occur in benign as well as in malignant lesions and do not permit differentiation between them.

Measurement of liver elasticity with acoustic radiation force impulse (ARFI) technology: an alternative noninvasive method for staging liver fibrosis in viral hepatitis.

PURPOSE: The acoustic radiation force impulse (ARFI) technology is a novel ultrasound method that provides information about the local elasticity of tissue in real-time. ARFI is integrated in a conventional ultrasound system. The aim of this exploratory study was to evaluate this new technique in the assessment of liver fibrosis in a cohort with chronic viral hepatitis B and C and to ascertain the most reliable hepatic segment for measurements. MATERIALS AND METHODS: 57 patients (27 female, 30 male, mean age 54 years) with chronic viral hepatitis B and C underwent ARFI imaging and consecutively liver biopsy. The results were compared to the histological fibrosis degree (F), which served as the reference. 20 healthy volunteers received ARFI quantification of different segments of the liver. RESULTS: The best ARFI assessments with the lowest rate of invalid measurements were carried out by an intercostal approach to segment VII/VIII of the liver. The ARFI velocities of the healthy group had a mean of 1.09 m/s (range 0.79 - 1.32 m/s), the means of the patient group ranged from 0.83 to 4.19 m/s. ARFI quantification correlated significantly with the histological fibrosis stage (p < 0.001). The area under the receiver operating characteristic (ROC) curves for the accuracy of ARFI imaging was 85 %, 92 % and 87 % for the diagnosis of moderate fibrosis (>or= F2), severe fibrosis (>or= F3) and cirrhosis ( = F 4), respectively. CONCLUSION: This study underscores the usefulness of ARFI as a quick method for assessing liver fibrosis or cirrhosis in patients with HBV or HCV. ARFI measurements of the liver should be performed via an intercostal access. Increasing ARFI velocities correlate with higher degree of hepatic fibrosis.

Muscle proteolysis and weight loss in a neonatal rat model of sepsis syndrome.

Our hypothesis is that nitrogen loss in septic neonates is caused by increased muscle proteolysis. Sprague-Dawley rat pups (P7) were injected intraperitoneally with NaCl or 4 mg/kg/BW lipopolysaccharide (LPS) and then sacrificed at 2, 4, 24, and 48 hr. Sepsis syndrome was confirmed by elevated serum tumor necrosis factor (24.6 ng/mL +/- 18.4 [LPS] and < 1.0 ng/mL [controls]; p < .05). Proteolysis in gastrocnemius/soleus muscle was analyzed by quantitation of tissue tyrosine loss. The neonatal rats injected with LPS had significant media tyrosine release at 24 hr compared to the controls (0.39 +/- 0.14 versus 0.25 +/- 0.11 micromol tyrosine/g muscle; p < .05). At 48 hr, LPS-induced muscle tyrosine release ceased (0.24 +/- 0.04 [control] versus 0.23 +/- 0.03 micromol tyrosine/g muscle [LPS]). After 48 hr, gastrocnemius/soleus weight was less in the LPS-injected rats (50.5 +/- 4.8 to 31.2 +/- 4.0 g; p < .0001). Similar changes were not seen in the extensor digitorum longus, suggesting that some muscles were relatively preserved. Also, LPS resulted in significant weight loss. We conclude that selective muscle proteolysis contributes to nitrogen loss in neonatal sepsis. Although proteolysis abates by 48 hr, short-term injury results in significant muscle-mass deficit.

N2, P3 and the lateralized readiness potential in a nogo task involving selective response priming.

Motor inhibition and its correlates in the event-related potential (ERP) are often studied in go/nogo tasks. However, go and nogo trials differ in their motor and their attentional requirements, rendering an interpretation of corresponding changes in ERP components difficult. As an alternative strategy to study motor inhibition, a hybrid choice-reaction go/nogo procedure involving selective response priming was used. Eighteen subjects performed the task. Response time (RT) and error measures as well as the lateralized readiness potential (LRP) indicated that responses were primed by flanker stimuli that were associated with one of the two possible responses. In nogo trials, selective response priming influenced the N2 amplitude whereas the P3 amplitude was unaffected. Because the N2 appeared irrespective of whether an erroneous response was correctable (in go trials) or not (in nogo trials), we conclude that the N2 reflects either the detection or the inhibition of an inappropriate tendency to respond.

Event related dynamics of 40 Hz electroencephalogram during visual discrimination task.

Visual priming tasks were presented to human subjects in two conditions: first, the warning stimulus contained information on the target stimulus, second, the warning stimulus only cued that a target was to come. The subjects had to respond as fast as possible to target stimuli with a certain button press. In both conditions 40 Hz EEG power showed reliably event related dynamics. Considering the differences between both conditions, 40 Hz power and motor response time effect sizes were found to be correlated 200 ms following warning stimuli. These results demonstrate that dynamics of 40 Hz activity are related to stimulus evaluation in sensorimotor processing during a visual discrimination task.