Does hepatic vein transit time performed with contrast-enhanced ultrasound predict the severity of hepatic fibrosis?

Previously published data suggest a hepatic vein transit time (HVTT) threshold of more than 24 s can distinguish mild to moderate from advanced fibrosis. In this study, we attempted to validate HVTT as a noninvasive index of hepatic fibrosis. Patients were scanned using real-time, pulse-inversion mode following bolus injections of the contrast agent Definity. HVTT was correlated with the degree of fibrosis obtained from contemporaneous liver biopsy. The study population included 40 patients with chronic liver disease and five healthy volunteers. Mean HVTT correlated with histologic grade as follows: absence/minimal fibrosis (n = 18), 25.6 ± 11.8 s; moderate fibrosis (n = 17), 21.5 ± 5.9 s; and severe fibrosis (n = 8), 20.9 ± 5.5 s, (p = .615). Poor sensitivity (57%) and specificity (43%) prevent validation of the previously published HVTT threshold as a surrogate marker of hepatic fibrosis. Further work investigating the different interaction of Definity, SonoVue and Levovist with the reticulo-endothelial system may help explain the discrepant results reported here.     

Early Detection of Liver Fibrosis in Rats Using 3-D Ultrasound Nakagami Imaging: A Feasibility Evaluation

We investigated the feasibility of using 3-D ultrasound Nakagami imaging to detect the early stages of liver fibrosis in rats. Fibrosis was induced in livers of rats (n = 60) by intraperitoneal injection of 0.5% dimethylnitrosamine (DMN). Group 1 was the control group, and rats in groups 2–6 received DMN injections for 1–5 weeks, respectively. Each rat was sacrificed to perform 3-D ultrasound scanning of the liver in vitro using a single-element transducer of 6.5 MHz. The 3-D raw data acquired at a sampling rate of 50 MHz were used to construct 3-D Nakagami images. The liver specimen was further used for histologic analysis with hematoxylin and eosin and Masson staining to score the degree of liver fibrosis. The results indicate that the Metavir scores of the hematoxylin and eosin-stained sections in Groups 1–4 were 0 (defined as early liver fibrosis in this study), and those in groups 5 and 6 ranged from 1 to 2 and 2 to 3, respectively. To quantify the degree of early liver fibrosis, the histologic sections with Masson stain were analyzed to calculate the number of fiber-related blue pixels. The number of blue pixels increased from (2.36 ± 0.79) × 10⁴ (group 1) to (7.68 ± 2.62) × 10⁴ (group 4) after DMN injections for 3 weeks, indicating that early stages of liver fibrosis were successfully induced in rats. The Nakagami parameter increased from 0.36 ± 0.02 (group 1) to 0.55 ± 0.03 (group 4), with increasing numbers of blue pixels in the Masson-stained sections (p-value < 0.05, t-test). We concluded that 3-D Nakagami imaging has potential in the early detection of liver fibrosis in rats and may serve as an image-based pathologic model to visually track fibrosis formation and growth.     

Non-invasive Assessment of Liver Fibrosis in a Rat Model: Shear Wave Elasticity Imaging Versus Real-Time Elastography

The purpose of this study was to investigate the diagnostic value of shear wave elasticity imaging (SWEI) and real-time elastography (RTE) in liver fibrosis induced by dimethylnitrosamine (DMN) and to compare the accuracy of these methods. Seventy male Wistar rats given a single intra-peritoneal injection of DMN and 10 control rats given a saline injection underwent SWEI and RTE to determine their shear wave velocity (V_s) and liver fibrosis (LF) index, respectively. Correlations between V_s or the LF index and histologic stage of liver fibrosis (S0–S4) were analyzed, and the diagnostic values of the techniques were assessed using a receiver operating characteristic curve. A positive correlation was found between V_s and stage of liver fibrosis (r = 0.947, p < 0.001) and between LF index and stage (S) of liver fibrosis (r = 0.662, p < 0.001). For V_s, the areas under the receiver operating characteristic curve for the diagnosis of fibrosis, S ≥ S1, S ≥ S2, S ≥ S3 and S = S4, were 0.983, 0.995, 0.999 and 0.964, respectively; for the LF index, the values were 0.871, 0.887, 0.761 and 0.839, respectively (all p < 0.001). V_s and the LF index values in rats with severe inflammatory activity were significantly higher than those in controls (p < 0.001). In conclusion, positive correlations exist between V_s or the LF index and the severity of liver fibrosis in rats. V_s is more accurate than the LF index in predicting liver fibrosis in rats. However, severe inflammatory activity may reduce the accuracy of both techniques.     

Liver Fibrosis Assessment Using Transient Elastography Guided with Real-Time B-mode Ultrasound Imaging: A Feasibility Study

Liver fibrosis is a kind of chronic damage of the liver and can lead to cirrhosis, one of the top 10 causes of death in the Western world. However, there is still a lack of noninvasive methods for diagnosing liver fibrosis. Fibroscan (Echosens, Paris, France), a device based on A-mode transient elastography, has shown promising results. In this study, a transient elastography system with real-time B-mode imaging for non-invasive liver fibrosis assessment, named Liverscan, was developed; its performance was tested and compared with that of the Fibroscan. A specific measurement probe was designed and fabricated with a B-mode ultrasound transducer fixed along the axis of a mechanical vibrator. It was integrated with the Liverscan to measure liver stiffness based on the shear wave propagation in liver tissues. The system was validated by mechanical indentation test using custom-made agar-gelatin phantoms with different stiffness. To further test its feasibility, in vivo measurements were conducted in 67 volunteers (age, 34 ± 3 years; body mass index, 21.3 ± 2.8 kg/m²; Mean ± SD., 34 male and 33 female), including 20 patients with various liver diseases, and 28 (19 male and 9 female) being tested by both Liverscan and Fibroscan. A significant linear correlation between the stiffness measured by the mechanical indentation test and that by the Liverscan (r = 0.973; p < 0.001) was obtained. The in vivo liver stiffness measured by Liverscan was also correlated with that by Fibroscan significantly (r = 0.886; p < 0.001). There was a significant difference in liver stiffness between the 20 patients and the other healthy subjects (14.1 ± 3.4 kPa vs. 10.5 ± 2.1 kPa; p = 0.001). The intra- and inter-observer tests indicated that the measurements were repeatable with intra-class correlation coefficients being 0.987 (p < 0.001) and 0.988 (p < 0.001), respectively. This study demonstrated that Liverscan with a specifically designed probe was able to measure and differentiate liver of different stiffness using the established measurement protocol under the guidance of real-time B-mode ultrasound imaging.     

Myocardial Strain Rate by Anatomic Doppler Spectrum: First Clinical Experience Using Retrospective Spectral Tissue Doppler from Ultra-High Frame Rate Imaging

Strain rate imaging by tissue Doppler (TDI) is vulnerable to stationary reverberations and noise (clutter). Anatomic Doppler spectrum (ADS) presents retrospective spectral Doppler from ultra-high frame rate imaging (UFR-TDI) data for a region of interest, that is, ventricular wall or segment, at one time instance. This enables spectral assessment of strain rate (SR) without the influence of clutter. In this study, we assessed SR with ADS and conventional TDI in 20 patients with a recent myocardial infarction and 10 healthy volunteers. ADS-based SR correlated with fraction of scarred myocardium of the left ventricle (r = 0.68, p < 0.001), whereas SR by conventional TDI did not (r = 0.23, p = 0.30). ADS identified scarred myocardium and ADS Visual was the only method that differentiated transmural from non-transmural distribution of myocardial scar on a segmental level (p = 0.002). Finally, analysis of SR by ADS was feasible in a larger number of segments compared with SR by conventional TDI (p < 0.001).     

Intrahepatic Transit Time Predicts Liver Fibrosis in Patients with Chronic Hepatitis B: Quantitative Assessment with Contrast-Enhanced Ultrasonography

We investigated the use of contrast-enhanced ultrasonography (CEUS) with quantitative measurements to assess the stages of liver fibrosis in patients with chronic hepatitis B. One-hundred twenty-two patients with chronic hepatitis B were divided into three groups according to the Scheuer scoring system pathologically and according to clinical evidence: mild fibrosis (S0 and S1, n = 36); moderate fibrosis (S2 and S3, n = 24); and cirrhosis (S4 and clinically typical cirrhosis, n = 62). CEUS of hepatic vessels and parenchyma was performed using the Cadence contrast pulse sequencing technique, with an intravenous bolus injection of a contrast agent (SonoVue). Real-time CEUS imaging of the liver was recorded and analyzed offline. Contrast arrival time, baseline, and peak intensity in the hepatic artery, portal vein, right hepatic vein, and liver parenchyma were used to calculate intrahepatic transit times, hepatic artery to hepatic vein transit time (HA-HVTT) and portal vein to hepatic vein transit time (PV-HVTT), as well as increased signal intensity (ISI). The correlations between these quantitative parameters and the stages of fibrosis were analyzed using Spearman rank correlation coefficients. HA-HVTT and PV-HVTT were shortened gradually with the progression of liver fibrosis. PV-HVTT was statistically significant differences existed between the two paired groups (mild vs. moderate vs. cirrhosis groups, p < 0.001), whereas HA-HVTT was changed significantly between mild and moderate or cirrhosis groups (p < 0.001). HA-HVTT and PV-HVTT changes were significantly correlated with liver fibrosis severity (r = −0.5930, p < 0.001; r = −0.8215, p < 0.001). Area under receiver operating characteristic curves for HA-HVTT and PV-HVTT were 0.891 ± 0.034 and 0.955 ± 0.020 at fibrosis scores ≥S2, and 0.785 ± 0.040 and 0.946 ± 0.018 at fibrosis score ≥S4, respectively. ISI values in the portal vein and liver parenchyma decreased with the severity of fibrosis. This study demonstrated that hepatic CEUS with quantitative measurements of intrahepatic transit time reflected the severity of liver fibrosis. The real-time CEUS imaging with use of software-based quantitative analysis could provide reliable information of hepatic hemodynamic changes to noninvasively assess the severity of liver fibrosis in patients with chronic hepatitis B. (E-mail: ding.hong@zs-hospital.sh.cn)     

Quantitative Tissue Echogenicity of the Neonatal Brain Assessed by Ultrasound Imaging

The aim of this study was to propose a method for measuring the echogenicity of several neonatal brain structures for quantitative interpretation of ultrasound images. To do this, 40 preterm neonates (24-34 weeks' gestation) with adequate birth weight for gestational age were studied. On the third day after delivery, anterior fontanelle ultrasound imaging of the brain was performed in standard coronal and sagittal views. Four regions-of-interest (ROIs) were identified: periventricular, choroid plexus, cerebellar vermis and basal ganglia. Two consecutive images from each ROI were digitally stored. For off-line analysis, the ROI corresponding to each structure was delineated and the mean pixel brightness (PB) calculated. In addition, the brightness of bone tissue obtained at the same depth of the studied ROI was calculated. This value was considered as the maximum possible echogenicity for that individual image. The relative echogenicity (RE) was then calculated as: PB ROI/PB BONE^*100. Differences in RE between the ROIs and RE variations according to gestational age and reliability reproducibility were determined. We found that among the studied structures, RE values (mean/SD) were significantly higher in the choroid plexus (mean [SD] 56.38 [6.0] and in the cerebellar vermis 51.20 [6.0] than in the basal ganglia 37.29 [5.7] and the periventricular area 37.04 [5.6]) (p < 0.05). These values showed no variation in relation to gestational age at birth. Interobserver reproducibility was 0.91 in the choroid plexus, 0.89 in the cerebellar vermis, 0.82 in basal ganglia and 0.77 in the anterior periventricular area. In conclusion, semiquantitative estimation of RE offers a reproducible method for evaluating at-risk areas of the neonatal brain. (E-mail: fpadilla@clinic.ub.es)     

Intravascular ultrasound area strain imaging used to characterize tissue components and assess vulnerability of atherosclerotic plaques in a rabbit model

The purpose of this study was to investigate the association of area strain and tissue components and vulnerability of atherosclerotic plaques in a rabbit model. Forty purebred New Zealand rabbits underwent balloon-induced abdominal aorta endothelium injury, then a high-cholesterol diet for 24 weeks. Intravascular ultrasound (IVUS) images of abdominal aortas were acquired in situ and two consecutive frames near the end-diastole were used to construct an IVUS elastogram. Histologic slices matched with corresponding IVUS images were stained for fatty and collagen components, smooth muscle cells (SMCs) and macrophages. Regions-of-interest (ROIs) in plaques were classified as fibrous, fibro-fatty or fatty according to histologic study. Vulnerability indexes of ROIs were calculated as (fat + macrophage)/(collagen + SMCs). The area strain of these ROIs was calculated by use of an in-house–designed software system with a block-matching–based algorithm. Area strain was significantly higher in fatty ROIs (0.056 ± 0.003) than in fibrous (0.019 ± 0.002, p < 0.001) or fibro-fatty ROIs (0.033 ± 0.003, p < 0.001). The sensitivity and specificity of area strain for fatty ROIs characterization was 75.0% and 80.2% (area under the curve [AUC] 0.858, 95% confidence interval [CI] = 0.800–0.916, p < 0.001) and 75.0% and 75.3% (AUC 0.859, 95% CI = 0.801–0.917, p < 0.001) for fibrous ROIs, as demonstrated by receiver operating characteristic curve analysis. Area strain was positively correlated with vulnerability index (r² = 0.495, p < 0.001), fatty components (r² = 0.332, p < 0.001) and macrophage infiltration (r² = 0.406, p < 0.001); and negatively correlated with collagen and SMC composition (r² = 0.115 and r² = 0.169, p < 0.001, respectively). Area strain calculation with IVUS elastography based on digital B-mode analysis is feasible and can be useful for tissue characterization and plaque vulnerability assessment.     

Comparison of Acoustic Radiation Force Impulse Imaging and Transient Elastography for Non-invasive Assessment of Liver Fibrosis in Patients with Chronic Hepatitis B

The aims of this study were to compare the performance of acoustic radiation force impulse (ARFI) elastography and transient elastography (TE) in the assessment of liver fibrosis in patients with chronic hepatitis B and to evaluate the impact of elevated alanine transaminase levels on liver stiffness assessment using ARFI elastography. One hundred eighty consecutive patients with chronic hepatitis B were enrolled in this study and evaluated with respect to histologic and biochemical features. All patients underwent ARFI elastography and TE. ARFI elastography and TE correlated significantly with histologically assessed fibrosis (r = 0.599, p < 0.001, for ARFI elastography; r = 0.628, p < 0.001, for TE) and necro-inflammatory activity (r = 0.591, p < 0.001, for ARFI elastography; r = 0.616, p < 0.001, for TE). Areas under the receiver operating characteristic curves for ARFI elastography and TE were 0.764 and 0.813 (p = 0.302, ≥stage 2), 0.852 and 0.852 (p = 1.000, ≥stage 3) and 0.825 and 0.799 (p = 0.655, S = 4), respectively. The optimum cutoff values for ARFI elastography were 1.63 m/s for stage ≥2, 1.74 m/s for stage ≥3 and 2.00 m/s for stage 4 in patients for whom alanine transaminase levels were evaluated. The cutoff values decreased to 1.24 m/s for ≥ stage 2, 1.32 m/s for ≥ stage 3 and 1.41 m/s for stage 4 in patients with normal alanine transaminase levels. ARFI elastography may be a reliable method for diagnosing the stage of liver fibrosis with diagnostic performance similar to that of TE in patients with chronic hepatitis B. In addition, liver stiffness values obtained with ARFI elastography, like those obtained with TE, may be influenced by alanine transaminase levels.     

Is E/E′ reliable in patients with regional wall motion abnormalities to estimate left ventricular filling pressure?

Background There is limited data on the diagnostic utility of the transmitral to mitral annular velocity (E/E′) by tissue Doppler imaging (TDI) in the presence of regional wall motion abnormalities (RWMA). We aimed to investigate whether the E/E′ is reliable in estimating left ventricular filling pressure (LVFP) despite RWMA. Methods One hundred thirty consecutive patients with myocardial infarction (MI) and subsequent RWMA referred for cardiac catheterization and echocardiography to measure LV pre-A pressure (LVP_PRE-A) and Doppler signals from the mitral inflow with tissue Doppler imaging (TDI) of the mitral annulus. All patients were classified into three groups according to RWMA of the segment adjacent to the E′-measuring point using TDI: 83 patients with normal wall motions of the basal septal and basal lateral segments (group A); 28 patients with RWMA of the basal septum (group B); and 19 patients with RWMA of the basal lateral segment (group C). Results Septal E/E′ correlated with LVP_PRE-A in groups A and C (r = 0.383, P < 0.001; r = 0.482, P = 0.037, respectively). Lateral E/E′ and LVP_PRE-A showed good correlation in groups A, B and C (r = 0.470, P < 0.001; r = 0.416, P = 0.028; r = 0.727, P < 0.001, respectively). The largest area under the receiver operating curve was obtained by the lateral E/E′ for the prediction of a high LVFP, irrespective of the location of RWMA. Conclusions In selected patients with abnormal wall motion of the basal septum, E/E′ measured at the septum was not representative for LVFP. Lateral E/E′ is reliable for the prediction of high LVFP, regardless of the site of RWMA.     

组织同步显像评价左心室内收缩失同步

目的 应用组织同步显像(TSI)观察左心室内心肌收缩运动失同步,探讨快速准确判定心室内运动不协调的方法。 方法 收集完全性左束支传导阻滞患者(LBBB组)28例及正常志愿者(对照组)28名,以TDI测量左心室12节段的收缩达峰时间(Ts),计算收缩达峰时间的标准差(Ts-SD)。分别设定不同的TSI处理时间,根据二维图像显示的色彩计算TSI积分。 结果 与对照组相比,LBBB组Ts延长,Ts-SD增大,TSI积分明显增加。LBBB组共有36个节段(36/336,10.71%)存在严重收缩后收缩(PSS)现象。TSI处理时间设定在收缩期时与等容舒张期时的严重PSS节段的平均TSI积分与仅设定在收缩期时差异有统计学意义(3.60±0.37 vs 2.30±0.48,P<0.001)。 结论 在正确设定处理时间的前提下,利用TSI可以直观评价左心室心肌收缩运动不同步。     

Value of Acoustic Radiation Force Impulse Imaging Elastography for Non-invasive Evaluation of Patients with Nonalcoholic Fatty Liver Disease

The goals of the work described here were to evaluate the clinical utility of acoustic radiation force impulse (ARFI) elastography in differentiating non-alcoholic fatty liver disease (NAFLD) histologic subtypes and to determine if ARFI elastography measurements correlate with the severity of liver fibrosis. We compared ARFI elastography measurements with clinical, biologic and histologic features (simple steatosis or steatohepatitis) in 64 patients with histologically proven NAFLD. ARFI elastography is suitable for distinguishing patients with non-alcoholic steatohepatitis from those with simple steatosis, with an area under the receiver operating characteristic curve (AUROC) of 0.867 (95% confidence interval = 0.782–0.953). There was a highly significant correlation (r = 0.843) between ARFI elastography measurements and fibrosis (p < 0.001). In patients with non-alcoholic steatohepatitis, the diagnostic performance of ARFI elastography in predicting significant fibrosis (F ≥ 2) had an AUROC of 0.944. ARFI elastography better predicted F = 4 fibrosis (AUROC = 0.984). In conclusion, ARFI elastography is a promising method for differentiating patients with non-alcoholic steatohepatitis from patients with simple steatosis and can also predict significant fibrosis in these patients.     

Multi-graphical analysis of dynamic PET

In quantitative dynamic PET studies, graphical analysis methods including the Gjedde–Patlak plot, the Logan plot, and the relative equilibrium-based graphical plot (RE plot) (Zhou Y., Ye W., Bra?i? J.R., Crabb A.H., Hilton J., Wong D.F. 2009b. A consistent and efficient graphical analysis method to improve the quantification of reversible tracer binding in radioligand receptor dynamic PET studies. Neuroimage 44(3):661–670) are based on the theory of a compartmental model with assumptions on tissue tracer kinetics. If those assumptions are violated, then the resulting estimates may be biased. In this study, a multi-graphical analysis method was developed to characterize the non-relative equilibrium effects on the estimates of total distribution volume (DV_T) from the RE plot. A novel bi-graphical analysis method using the RE plot with the Gjedde–Patlak plot (RE-GP plots) was proposed to estimate DV_T for the quantification of reversible tracer kinetics that may not be at relative equilibrium states during PET study period. The RE-GP plots and the Logan plot were evaluated by 19 [¹¹C]WIN35,428 and 10 [¹¹C]MDL100,907 normal human dynamic PET studies with brain tissue tracer kinetics measured at both region of interest (ROI) and pixel levels. A 2-tissue compartment model (2TCM) was used to fit ROI time activity curves (TACs). By applying multi-graphical plots to the 2TCM fitted ROI TACs which were considered as the noise-free tracer kinetics, the estimates of DV_T from the RE-GP plots, the Logan plot, and the 2TCM fitting were equal to each other. For the measured ROI TACs, there was no significant difference between the estimates of the DV_T from the RE-GP plots and those from 2TCM fitting (p = 0.77), but the estimates of the DV_T from the Logan plot were significantly (p < 0.001) lower, 2.3% on average, than those from 2TCM fitting. There was a highly linear correlation between the ROI DV_T from the parametric images (Y) and those from the ROI kinetics (X) by using the RE-GP plots (Y = 1.01X + 0.23, R² = 0.99). For the Logan plot, the ROI estimates from the parametric images were 13% to 83% lower than those from ROI kinetics. The computational time for generating parametric images was reduced by 69% on average by the RE-GP plots in contrast to the Logan plot. In conclusion, the bi-graphical analysis method using the RE-GP plots was a reliable, robust and computationally efficient kinetic modeling approach to improve the quantification of dynamic PET.     

Acoustic Radiation Force Impulse Elastography for Chronic Liver Disease: Comparison with Ultrasound-Based Scores of Experienced Radiologists,Child-Pugh Scores and Liver Function Tests

The purpose of our study was to investigate whether acoustic radiation force impulse (ARFI) elastography provides better diagnostic performance for diagnosis of chronic liver disease and correlates better with Child-Pugh scores and liver function tests, compared with an ultrasound (US) scoring system based on visual assessment of conventional B-mode US images by experienced radiologists. Five hundred and twenty-one patients with clinically proven chronic liver disease (n = 293), fatty liver (n = 95) or normal liver (n = 133) were included in this study. B-mode liver US and ARFI elastography were performed in all patients. ARFI elastography was performed at least five times, with each measurement obtained at a different area of the right hepatic lobe; mean shear wave velocity (SWV) was calculated for each patient. The mean SWV was compared with US-based scores from two radiologists (based on liver surface nodularity, parenchyma echotexture and hepatic vein contour), Child-Pugh scores and liver function tests. The mean SWV of the normal liver group was 1.08 m/s ± 0.15; of the fatty liver group, 1.02 m/s ± 0.16; and of the chronic liver disease group, 1.66 m/s ± 0.60 (p < 0.001). The area under the receiver operating characteristics curve of the mean SWV in ARFI elastography was significantly higher than that of the conventional B-mode US-based scores by two radiologists (0.89 vs. 0.74 and 0.77, p < 0.05), with a sensitivity of 75.4% and a specificity of 89.5% at the cut-off value of 1.22 m/s. The sensitivity of the mean SWV was significantly higher than the US-based scores (p < 0.001), although the specificity was not (p > 0.05). The mean SWV was better correlated with Child-Pugh scores and all liver function tests (except total protein) than the US-based scores from two radiologists. In conclusion, ARFI elastography showed better diagnostic performance than visual assessment of experienced radiologists for diagnosis of chronic liver disease, as well as for evaluation of the severity of chronic liver disease. (E-mail: leejy4u@snu.ac.kr)     

Acoustic Radiation Force Impulse Imaging for Reactive and Malignant/Metastatic Cervical Lymph Nodes

The aim of this study was to compare lymph node stiffness using acoustic radiation force impulse (ARFI) imaging in patients with cervical lymph node swelling. Forty-two cervical lymph nodes (reactive, n = 22; metastatic, n = 20) from 19 patients (13 men, 6 women; mean age, 63.68 ± 14.9 y; range, 23–85 y) were examined between September 2011 and March 2012. The shear wave velocity (SWV, m/s) of each lymph node was evaluated by ARFI imaging. SWV of reactive lymph nodes was 1.52 ± 0.48 m/s, and that of metastatic/malignant lymph nodes was 2.46 ± 0.75 m/s. A SWV > 1.9 m/s was very useful metastatic lymph node classification, with 95.0% specificity, 81.8% sensitivity and 88.0% overall accuracy. The area under the receiver operating characteristic curve was 0.923 (95% confidence interval, 0.842–1.000). ARFI imaging can be useful in the differentiation of reactive and malignant/metastatic cervical lymph nodes.     

犬肝纤维化模型MR弥散张量成像及其与CT灌注参数、VEGF表达的相关性

目的 利用DTI测定犬肝纤维化模型的ADC值、FA值,评估肝纤维化程度,分析其与CT灌注参数及VEGF表达水平的相关性.方法 健康中华田园犬15只,随机分成实验组(n=10)和对照组(n=5).实验组犬经腹腔注射50％CCl4油溶液,辅以高脂饮食,建立犬肝纤维化模型.对2组犬每隔4周行MR DTI、CT灌注成像及肝穿活检.根据病理分期分组,分析各组MR DTI参数ADC值、FA值,并与CT灌注参数及VEGF表达水平进行对照.结果 成功获得各期肝纤维化模型;随肝纤维化进展,ADC值逐渐降低(P＜0.05),FA值总体呈上升趋势(P＞0.05);ADC值与PVP、TLP呈正相关;VEGF表达水平随肝纤维化进展而明显增高(P＜0.05).结论 对犬行腹腔注射CCl4油溶液辅以高脂饮食可成功模拟人类从肝细胞变性-肝纤维化-肝硬化的全过程;MR DTI能反映肝纤维化各期的血流动力学变化趋势;VEGF可能在慢性肝病所致肝纤维化过程中起重要作用.     

磁共振T1 mapping、T2 mapping评估大鼠肝纤维化和肝脂肪变性

目的 采用磁共振T1 mapping、T2 mapping评估大鼠肝纤维化和肝脂肪变性，观察其应用价值。方法 将80只大鼠随机分成实验组（n=70）对照组（n=10）， 分别于背部注射四氯化碳橄榄油溶液及生理盐水，制作大鼠肝纤维化模型。于注药后第4、6、8、10和12周，分别随机选取实验组14只和对照组2只大鼠采集MRI，测量肝实质T1值和T2值，并行组织病理检查。根据病理结果将大鼠肝纤维化划分为S₀~S₄期，脂肪变性划分为F₀~F₄度，比较肝纤维化各期T1值和T2值，分析其与肝纤维化及肝脂肪变性相关性。结果 S₀期大鼠肝脏T1值和T2值与肝纤维化各期差异有统计学意义（P均<0.05），S₁期[（402.01±57.14）ms]肝实质T1值较S₃期[（514.83±87.10）ms]和S₄期[（518.72±36.50）ms]短（P均<0.05），S₂期[（417.49±47.00）ms]肝实质T1值较S₄期短（P<0.05）；S₁期[（65.12±9.46）ms]肝实质T2值较S₄期[（55.33±7.30）ms]略延长（P<0.05）。T1值与肝纤维化程度呈正相关（r=0.68，P<0.01），T2值与脂肪变性程度呈正相关（r=0.72，P<0.01）。结论 磁共振T1 mapping可无创评估大鼠肝纤维化，T2 mapping可无创评估大鼠肝脂肪变性，有望为临床诊断肝纤维化和肝脂肪变性提供新的影像学方法。     

超声弹性成像组织弥散定量分析技术在脂肪肝分度中的应用

目的 探讨超声弹性组织弥散定量分析技术在脂肪肝分度中的应用价值。方法 将75例脂肪肝患者(脂肪肝组)分为轻度(28例)、中度(26例)、重度(21例)3亚组,另设正常对照组30名。对所有受检者进行常规超声扫查后,使用实时组织超声弹性成像技术进行扫查,并行组织弥散定量分析,测量ROI内应变均值。结果 各组间超声弹性成像图表现有不同特点。弹性成像ROI内应变均值在各组间差异有统计学意义(P<0.05)。结论 超声弹性组织弥散定量分析技术在评价脂肪肝程度中具有独特优势和广阔的应用前景。     

Hepatic Perfusion Parameters of Contrast-Enhanced Ultrasonography Correlate With the Severity of Chronic Liver Disease

In the study described here, we introduced a new ratio acquired with contrast-enhanced ultrasonography (CEUS): a liver parenchyma blood supply ratio that differentiates arterial and portal phases. Our purpose was to determine whether this ratio and other liver parenchyma perfusion parameters acquired with CEUS can be correlated with the severity of chronic liver disease. Twelve patients with non-cirrhotic chronic liver disease, 35 patients with cirrhosis (child class A: n = 10; child class B: n = 13; child class C: n = 12) and 21 healthy volunteers were examined by CEUS. Time–intensity curves were drawn for regions of interest located in liver parenchyma and right kidney cortex using QLAB quantification software. The arterial and portal phases were differentiated by the time to the maximum enhancement of right kidney and liver parenchyma perfusion data acquired from the time–intensity curves: the intensity of liver parenchyma perfused by hepatic arterial flow (I_ap), the intensity of total perfusion of liver parenchyma (I_peak), the intensity of liver parenchyma perfused by portal venous flow (I_pp) and the ratio of portal perfusion to total perfusion of liver parenchyma expressed by the parameters I_pp/I_peak, I_peak, I_pp and I_pp/I_peak significantly decreased in patients with cirrhosis and in patients with non-cirrhotic chronic liver disease, whereas I_ap increased. The parameters I_pp, I_peak, I_pp/I_peak and I_ap correlated with the severity of chronic liver disease (r = ?0.938, p < 0.001; r = ?0.790, p < 0.001; r = ?0.931 p < 0.001; r = 0.31, p < 0.05). The diagnostic accuracy rates for cirrhosis expressed as areas under receiver operating characteristic curves were 0.93 for I_peak, 0.98 for I_pp, 0.98 for I_pp/I_peak, and 0.69 for I_ap. Liver parenchyma perfusion parameters obtained by CEUS were correlated with the severity of chronic liver disease and have the potential to assess cirrhosis non-invasively.     

Immediate Effects of Single-Session Proprioceptive Neuromuscular Facilitation Exercises on the Sit-to-Stand Strategy in Patients With Chronic Lumbar Spinal Disc Disease: A Preliminary Study

ObjectiveThe purpose of this study was to measure the immediate effects of single-session proprioceptive neuromuscular facilitation exercises on the sit-to-stand (STS) task and level of pain in patients with chronic low back pain.MethodsFifty-three patients were assigned to the control and intervention groups. The total time was 30 minutes (each exercise 5 minutes). The minimum vertical ground reaction force (VGRF_min) and maximum vertical ground reaction force (VGRF_max) and time phases (T_min – time to counterforce, T_max – time to peak force, T_tot – time to post-peak rebound force) were measured with a Kistler force plate in eyes-open and eyes-closed conditions during the STS task. Pain level was determined on a numeric rating scale.ResultsMain effects were observed only in the intervention group: decreasing pain value (F = 25.398, P < .0001), increasing T_min (F = 5.72, P = .0044), decreasing T_max (F = 3.43, P = .04), and decreasing T_tot (F = 3.935, P = .02258). There was a main effect of the eyes factor on VGRF_min (F = 12.53, P < .0001) and VGRF_max (F = 7.16, P < .01).ConclusionImmediate effects of single-session proprioceptive neuromuscular facilitation exercises were observed in decreasing the level of pain. Adaptation effects were noted in the retention test. The STS task could be optimized in time phases and dynamic movements in patients with chronic low back pain.