Frequency Specific Ultrasound Attenuation is Sensitive to Trabecular Bone Structure

This study investigated the efficacy of frequency modulated ultrasound attenuation in the assessment of the trabecular structural properties. Four frequency modulated signals were created to represent four frequency bands centered at 500 kHz, 900 kHz, 1.3 MHz and 1.7 MHz with the bandwidth of 400 kHz. Five 1-cm trabecular cubes were harvested from fresh bovine distal femur. The cubes underwent four steps of demineralization process to expand the sample size to 25 with the greater variations of the structural properties for the better correlation study. Pearson correlation study was performed between the ultrasound attenuation in four frequency bands and the trabecular structural properties. The results showed that correlations of frequency modulated ultrasound attenuation to the trabecular structural properties are dependent on frequency bands. The attenuation in proximal-distal orientation had the highest correlation to BV/TV (R² = 0.73, p < 0.001) and trabecular thickness (R² = 0.50, p < 0.001) at the frequency band centered at 1.7 MHz. It was equivalent in the four frequency bands in correlation to the trabecular number (average R² = 0.80, p < 0.001) and to the trabecular separation (average R² = 0.83, p < 0.001). The attenuation in anterio-posterial orientation had the highest correlation to BV/TV (R² = 0.80, p < 0.001) and trabecular thickness (R² = 0.71, p < 0.001) at the frequency band centered at 1.3 MHz. The attenuation in the first frequency band was the most sensitive to the trabecular number (R² = 0.71, p < 0.001) and trabecular separation (R² = 0.80, p < 0.001). No significant correlation was observed for the attenuation in medial-lateral orientation across the four frequency bands.     

Effect of Bone Marrow on Acoustic Properties of Trabecular Bone - 3D Finite Difference Modeling Study

The composition of bone marrow is influenced by many factors, such as age and diseases. The present numerical study investigates the contribution of marrow on the acoustic measurements of trabecular bone. Cylindrical bone samples (n = 11), extracted from three anatomical sites of human cadaver knees, were imaged with a high-resolution microtomography (microCT). Three-dimensional finite difference time domain (FDTD) models (Wave 3000 Pro 2.2, Cyberlogic Inc., NY, USA) were created using the segmented microCT images of each sample. First, we evaluated the effect of voxel size on the computer resource requirements, morphological parameters and acoustic simulations. Second, the effect of bone marrow on ultrasonic measurements was assessed. The simulations were repeated with two voxel sizes before and after substitution of bone marrow (i.e., fat) with water. The voxel size of the FDTD mesh controlled the fine structure of the modeled calcified matrix and significantly affected the simulation results. However, present simulations showed that the effect of bone marrow on ultrasound parameters can be reliably simulated with the applied voxel sizes of 72 and 90 μm. Ultrasound attenuation and speed were found (p < 0.01) to decrease and increase, respectively, when bone marrow was substituted with water. Moreover, reflection from the surface of the sample increased (p < 0.01) and backscatter from internal structures decreased (p < 0.01) after removal of marrow. The effect of bone marrow on the acoustic properties was stronger in samples with low bone volume fraction. The present results indicate that the amount and quality of bone marrow significantly influence the acoustic properties of trabecular bone. Possible interindividual differences in the composition of bone marrow may increase uncertainty in clinical ultrasound diagnostics of osteoporosis. Importantly, the effect is most significant in osteoporotic low-density bone. (E-mail: Antti.Aula@uku.fi)     

Signal of Interest Selection Standard for Ultrasonic Backscatter in Cancellous Bone Evaluation

The aim of this study was to examine the effect of the backscattered signal of interest (SOI) on ultrasonic cancellous bone evaluation. In vitro backscatter measurements were performed using 16 bovine cancellous bone specimens and six different transducers with central frequencies of 0.5, 1, 2.25, 3.5, 5 and 10 MHz. The SOI for signal analysis was selected by a rectangular window. The delay (T1) and duration (T2) of the time window were varied, and the apparent integrated backscatter (AIB) and its correlation to bone volume fraction (BV/TV) were calculated. The results indicate that in addition to affecting the measured value of AIB, the SOI influences the observed correlation between AIB and BV/TV. Strong positive correlations were observed for short T1 (0.5 MHz: ≤6 μs, 1 MHz: ≤3 μs, 2.25 and 3.5 MHz: ≤2 μs, 5 and 10 MHz: ≤1 μs). However, strong negative correlations were observed when T1 was long (0.5 MHz: >9 μs, 1 MHz: >7 μs, 2.25 and 3.5 MHz: >3 μs, 5 and 10 MHz: >2 μs). The T2 value, especially low values (≤3 μs), also influenced the correlation coefficients. Positive correlations were more commonly observed at lower frequencies (i.e., 0.5–1 MHz), whereas negative correlations were more common at higher frequencies (i.e., 2.25–10 MHz). An explicit standard for in vitro SOI selection and cancellous bone assessment was proposed for a broad frequency range (0.5–10 MHz). Current conflicting findings are explained, and constructive suggestions for ultrasonic backscatter cancellous bone evaluation are provided.     

用超声声速和声衰减预测人松质骨的生物力学性质

本文介绍了用超声波声速、声衰减及两者的组合来预测人松质骨在准静态和动态加载条件下的生物力学性质的实验和分析。实验结果表明：（１）超声波的声速（ＵＶ）和声衰减（ＢＵＡ）的线性组合显然比单个ＵＶ或ＢＵＡ更能准确地预测人松质骨在准静态和动态加载条件下的力学性质；（２）松质骨试样的平均动态压缩弹性模量Ｅ、强度Ｓ分别比准静态加载时的相应力学性质参数高８２％和６３％，而松质骨试样的平均动态压缩终应变εｍ则比准静态加载时低１８％。     

Ultrasound Speed of Sound Measurements in Trabecular Bone Using the Echographic Response of a Metallic Pin

Bone quality is an important parameter in spine surgery, but its clinical assessment remains difficult. The aim of the work described here was to demonstrate in vitro the feasibility of employing quantitative ultrasound to retrieve bone mechanical properties using an echographic technique taking advantage of the presence of a metallic pin inserted in bone tissue. A metallic pin was inserted in bone tissue perpendicular to the transducer axis. The echographic response of the bone sample was determined, and the echo of the pin inserted in bone tissue and water were compared to determine speed of sound, which was compared with bone volume fraction. A 2-D finite-element model was developed to assess the effect of positioning errors. There was a significant correlation between speed of sound and bone volume fraction (R² = 0.6). The numerical results indicate the relative robustness of the measurement method, which could be useful to estimate bone quality intra-operatively.     

Numerical Analysis of Uncertainties in Dual Frequency Bone Ultrasound Technique

Quantitative ultrasound (QUS) measurements are used in the diagnostics of osteoporosis. However, the variation in the thickness and composition of the overlying soft tissue causes significant errors to the bone QUS parameters and diminishes the reliability of the technique in vivo. Recently, the dual frequency ultrasound (DFUS) technique was introduced to minimize the errors related to soft tissue effects. In this study, the significance of soft tissue induced errors and their elimination with the DFUS technique were simulated using the finite difference time domain technique. Furthermore, we investigated the potential of the DFUS corrected integrated reflection coefficient (IRC) of bone to detect changes in the cortical bone density. The effects of alterations in the thickness of fat and lean tissue layers and the inclination between the soft-tissues and between the soft tissue-bone layers were simulated. When the angle of the soft tissue interface was zero, i.e., perpendicular to the incident ultrasound beam, the DFUS-calculated soft tissue composition correlated highly linearly with the true soft tissue composition. The inclination between the soft tissue-bone layers was found to be critical. Even a 2-degree inclination between the soft tissue and the bone surface induced an almost 18% relative error in the corrected IRC. Increasing the inclination between the soft tissue layers increased the error in the DFUS-calculated lean and fat tissue thickness. This error was especially significant at inclination angles greater than 20 degrees. The significant soft tissue induced errors in IRC values (>300 %) could be effectively minimized (<10 %) by means of the DFUS correction. Importantly, after the DFUS correction, physiologically relevant variation in the cortical bone density could be detected (p < 0.05). (E-mail: Markus.Malo@uef.fi)     

Ultrasound Imaging of Long Bone Fractures and Healing with the Split-Step Fourier Imaging Method

We applied the split-step Fourier imaging method to back-propagate the ultrasound zero-offset wavefields acquired on the bone surface to the sources of scatterers, which are the reflecting interfaces. The method required, as an input, an estimated slowness (reciprocal of half the velocity) model to map the time-dependent sonogram to the depth image, which provides the geometric properties of the interfaces. The slowness was approximated by a depth-dependent term and a first-order spatially varying perturbation. Simulated data sets were used to validate the method. The reconstructed images show proper mapping of the interfaces and the fracture, and a reasonable cortical thickness measurement with 8.3% error. The images also illustrate clearly the bone fracture healing process of a 1-mm-wide 45° inclined crack with different in-filled tissue velocities for various healing stages. Reconstruction of a fractured bone plate using data from an in vitro experiment is also presented. This study suggests that the proposed imaging method has good potential in quantification of bone fractures and monitoring of the fracture healing process.     

Influence of overlying soft tissues on trabecular bone acoustic measurement at various ultrasound frequencies

Ultrasound (US) has been introduced as a promising tool for osteoporosis diagnostics. However, soft tissues overlying the bones affect reliability of the ultrasound (US) techniques. In this in vitro study, the effect of soft tissues on bone US measurements was investigated numerically and experimentally. Particularly, the dependence of the error induced by soft tissues on the applied US frequency (0.3 to 6.7 MHz) was addressed. For these aims, human trabecular bone samples (n = 25) were measured using acoustic, dual energy x-ray absorptiometry (DXA) and mechanical techniques. US attenuation, speed, reflection and backscattering were determined from the through-transmission and pulse-echo measurements. Numerical correction, based on the inclusion of acoustic characteristics of specific soft tissue components, i.e., adipose and lean tissues, was derived for the analysis of experimental measurements. Values of US parameters, interrelationships between the US parameters and mechanical properties, as well as the errors induced by the soft tissues, were significantly dependent on the US frequency. The errors induced by the soft tissues on the US measurement were typically reduced by approximately 50% after introduction of the numerical correction technique. Thereby, the acoustic prediction of mechanical properties of trabecular bone was also improved. We conclude that the numerical correction of the contribution of overlying soft tissues on acoustic measurements can reduce uncertainties related to in vivo US measurements.     

Ultrasound Arthroscopy of Human Knee Cartilage and Subchondral Bone in Vivo

Arthroscopic ultrasound imaging enables quantitative evaluation of articular cartilage. However, the potential of this technique for evaluation of subchondral bone has not been investigated in vivo. In this study, we address this issue in clinical arthroscopy of the human knee (n = 11) by determining quantitative ultrasound (9 MHz) reflection and backscattering parameters for cartilage and subchondral bone. Furthermore, in each knee, seven anatomical sites were graded using the International Cartilage Repair Society (ICRS) system based on (i) conventional arthroscopy and (ii) ultrasound images acquired in arthroscopy with a miniature transducer. Ultrasound enabled visualization of articular cartilage and subchondral bone. ICRS grades based on ultrasound images were higher (p < 0.05) than those based on conventional arthroscopy. The higher ultrasound-based ICRS grades were expected as ultrasound reveals additional information on, for example, the relative depth of the lesion. In line with previous literature, ultrasound reflection and scattering in cartilage varied significantly (p < 0.05) along the ICRS scale. However, no significant correlation between ultrasound parameters and structure or density of subchondral bone could be demonstrated. To conclude, arthroscopic ultrasound imaging had a significant effect on clinical grading of cartilage, and it was found to provide quantitative information on cartilage. The lack of correlation between the ultrasound parameters and bone properties may be related to lesser bone change or excessive attenuation in overlying cartilage and insufficient power of the applied miniature transducer.     

Quantitative Ultrasound Biomarkers Based on Backscattered Acoustic Power: Potential for Quantifying Remodeling of the Human Cervix during Pregnancy

As pregnancy progresses, the cervix remodels from a rigid structure to one pliable enough to allow delivery of a fetus, a process that involves progressive disorganization of cervical microstructure. Quantitative ultrasound biomarkers that may detect this process include those derived from the backscattered echo signal, namely, acoustic attenuation and backscattered power loss. We recently reported that attenuation and backscattered power loss are affected by tissue anisotropy and heterogeneity in the ex vivo cervix. In this study, we compared attenuation and backscattered power difference in a group of women in early pregnancy (first trimester) with those in a group in late pregnancy (third trimester). We observed a significant decrease in the backscattered power difference in late as compared with early pregnancy, suggesting decreased microstructural organization in late pregnancy, a finding that is consistent with animal models of cervical remodeling. In contrast, we found no difference in attenuation between the time points. These results suggest that the backscattered power difference, but perhaps not attenuation, may be a useful clinical biomarker of cervical remodeling.     

Effect of Corneal Hydration on Ultrasound Velocity and Backscatter

The cornea's acoustic properties (speed-of-sound, backscatter, attenuation) are related to its state of hydration. Our aim was to determine these properties as a function of corneal hydration using high-frequency ultrasound. Bovine corneas were suspended in a Dexsol-equivalent corneal preservation medium at 33 °C and then immersed successively in 75%, 50% and 25% medium and distilled water. Using a 38-MHz focused ultrasound transducer, we measured speed-of-sound and corneal thickness (n = 8) and stromal backscatter (n = 6) after 45-min immersion in each medium. Corneal speed-of-sound was modeled as a function of corneal thickness. We found the mean speed-of-sound to be 1605.4 ± 2.9 m/s in normotensive medium. The maximum observed speed-of-sound was 1616 m/s. As we decreased medium tonicity, the cornea swelled and the speed-of-sound decreased, reaching 1563.0 ± 2.2 m/s in water. Average corneal thickness increased from 969 ± 93 μm in 100% medium to 1579 ± 104 μm in water. Going from 100% medium to water, stromal backscatter (midband-fit) increased from –60.0 ± 0.8 dBr to –52.5 ± 3.5 dBr, spectral slope increased from –0.119 ± 0.021 to –0.005 ± 0.030 dB/MHz and attenuation coefficient decreased from 0.927 ± 0.434 to 0.010 ± 0.581 dB/cm-MHz. The observed correlation between acoustic backscatter and attenuation with the speed-of-sound offers a potential means for more accurate determination of speed-of-sound and, hence, thickness in edematous corneas. (E-mail: ros2012@med.cornell.edu)     

超声胎儿鼻骨测量在筛查胎儿畸形中的应用价值

目的 探讨超声胎儿鼻骨测量在胎儿畸形筛查中的应用价值.方法 对我院近年超声筛查异常55例(观察组)的超声资料进行回顾性分析,观察胎儿鼻骨发育情况,并与健康体检的孕妇(对照组)进行比较,分析鼻骨长度与孕周的关系,同时记录患儿其他的发育畸形情况.结果 观察组有28例声像图表现为鼻骨强回声连续性中断,诊断为胎儿鼻骨缺失;27例声像图表现为胎儿鼻骨短小,诊断为鼻骨发育不良.对两组胎儿鼻骨长度与孕周关系进行Logistic线性回归分析(线性回归方程为y=1.371 +3.013x),差异有统计学意义(=28.557,P=0.000),同时发现观察组胎儿伴有多种发育畸形;对照组未见发育异常,各孕周鼻骨长度及检出率均正常.观察组中鼻骨短小的27例与对照组各孕期鼻骨长度比较差异均有统计学意义(P＜0.05).结论 产前(孕中期)超声检测胎儿鼻骨发育情况,能有效提高染色体异常的检出率.     

Dynamic Changes of Integrated Backscatter,Attenuation Coefficient and Bubble Activities During High-Intensity Focused Ultrasound (HIFU) Treatment

This paper simultaneously investigated the transient characteristics of integrated backscatter (IBS), attenuation coefficient and bubble activities as time traces before, during and after HIFU treatment, with different HIFU parameters (acoustic power and duty cycle) in both transparent tissue-mimicking phantoms and freshly excised bovine livers. These dynamic changes of acoustic parameters and bubble activities were correlated with the visualization of lesion development selected from photos, conventional B-mode ultrasound images and differential IBS images over the whole procedure of HIFU treatment. Two-dimensional radiofrequency (RF) data were acquired by a modified diagnostic ultrasound scanner to estimate the changes of mean IBS and attenuation coefficient averaged in the lesion region, and to construct the differential IBS images and B-mode ultrasound images simultaneously. Bubble activities over the whole procedure of HIFU treatment were investigated by the passive cavitation detection (PCD) method and the changes in subharmonic and broadband noise were correlated with the transient characteristics of IBS and attenuation coefficient. When HIFU was switched on, IBS and attenuation coefficient increased with the appearance of bubble clouds in the B-mode and differential IBS image. At the same time, the level of subharmonic and broadband noise rose abruptly. Then, there was an initial decrease in the attenuation coefficient, followed by an increase when at lower HIFU power. As the lesion appeared, IBS and attenuation coefficient both increased rapidly to a value twice that of normal. Then the changes in IBS and attenuation coefficient showed more complex patterns, but still showed a slower trend of increases with lesion development. Violent bubble activities were visible in the gel and were evident as strongly echogenic regions in the differential IBS images and B-mode images simultaneously. This was detected by a dramatic high level of subharmonic and broadband noise at the same time. These bubble activities caused fluctuations in IBS and attenuation coefficient during HIFU treatment. After HIFU, IBS and attenuation coefficient decreased gradually accompanied by the fadeout of bright hyperechoic spot in the B-mode and differential IBS image, but were still higher than normal when they were stable. The increases of IBS and attenuation coefficient were greater when using higher acoustic power or a higher duty cycle of the therapeutic emission. These experiments indicated that the bubble activities had the dominant effects on the transient characteristics of IBS and attenuation. This should be taken into consideration when using the dynamic acoustic-property changes for the potentially real-time monitoring imaging of HIFU treatment. (E-mail: mxwan@mail.xjtu.edu.cn)     

超声全程动态监测下儿童鼻骨骨折可视化复位的临床研究

【摘要】 目的 评估超声全程动态监测在儿童鼻骨骨折治疗中的应用价值,分析超声全程动态监测引导治疗儿童鼻骨骨折的可行性及效果。方法 回顾性分析2017年4月至2018年12月,将我科室接诊48例儿童鼻骨骨折患者。男33例,女15例;年龄3～12岁,平均年龄6.5岁;18例为撞伤,12例为压砸伤,11例为打伤,7例为交通伤。其中II型22例,III型16例,IV型10例。手法整复实施时间时间为距受伤20～81 h,平均43.5h。均采用术前超声及CT检查,术中超声全程动态监测复位器位置、骨折复位及鼻腔填塞情况,记录手法整复实施时间、二次手法整复率、CT扫描次数、CT评分、鼻通气评分等。结果 48例病人中,所有患者均在满足全身麻醉条件下立即行手法整复治疗,平均术前时间22±6小时平均住院天数为4.52±1.6天,二次调整率为0,CT扫描次数为平均2次。术前术后CT评分及鼻通气评分均有显著差异。结论 超声全程动态监测下儿童鼻骨骨折闭合复位,能提前手法整复时间,透过超声探头全程监测复位器与骨折块位置情况、复位器撬拨作用下骨折端移动情况、填塞物填塞情况、填塞物作用下骨折块移动情况,使鼻骨骨折闭合性复位由盲视变为可视,缩短治疗时间,提高复位准确率,使临床深入总结儿童鼻骨骨折特点及复位方法成为可能。     

Analysis of Ultrasonic Waves Propagating in a Bone Plate over a Water Half-Space with and without Overlying Soft Tissue

Recent in vitro studies have shown that guided waves can characterize bone properties. However, for clinical applications to be viable, the soft-tissue layer should be considered. This study examined the effect of soft tissue on guided waves using a bovine bone plate over a water half-space and overlaid by a 4-mm gelatin-based soft-tissue mimic. The data (with and without soft tissue) clearly show a high-frequency, fast-propagating wave packet and a low-frequency, delayed phase group. The presence of soft tissue attenuates the signals significantly and increases mode density and number as predicted by theory. The data retain higher frequency content than the bone-plate data at large offsets. Using theoretical dispersion curves, the guided modes can be identified with mode 1 (similar to the A0 Lamb mode) minimally affected by the addition of soft tissue. There is infiltration of high-frequency, late-arriving energy within the low-velocity guided-wave regime. Results of travel-time calculation suggest that P-wave and PP-reflections/multiples within the soft tissue may be responsible for the high-frequency oscillations.     

Automated Registration of Freehand B-Mode Ultrasound and Magnetic Resonance Imaging of the Carotid Arteries Based on Geometric Features

An automated method for registering B-mode ultrasound (US) and magnetic resonance imaging (MRI) of the carotid arteries is proposed. The registration uses geometric features, namely, lumen centerlines and lumen segmentations, which are extracted fully automatically from the images after manual annotation of three seed points in US and MRI. The registration procedure starts with alignment of the lumen centerlines using a point-based registration algorithm. The resulting rigid transformation is used to initialize a rigid and subsequent non-rigid registration procedure that jointly aligns centerlines and segmentations by minimizing a weighted sum of the Euclidean distance between centerlines and the dissimilarity between segmentations. The method was evaluated in 28 carotid arteries from eight patients and six healthy volunteers. First, the automated US lumen segmentation method was validated and optimized in a cross-validation experiment. Next, the effect of the weighting parameter of the proposed registration dissimilarity metric and the control point spacing in the non-rigid registration was evaluated. Finally, the proposed registration method was evaluated in comparison to an existing intensity-and-point-based method, a registration using only the centerlines and a registration using manual US lumen segmentations. Registration accuracy was measured in terms of the mean surface distance between manual US segmentations and the registered MRI segmentations. The average mean surface distance was 0.78 ± 0.34 mm for all subjects, 0.65 ± 0.09 mm for healthy volunteers and 0.87 ± 0.42 mm for patients. The results for the complete set were significantly better (Wilcoxon test, p < 0.01) than the results for the intensity-and-point-based method and the centerline-based registration method. We conclude that the proposed method can robustly and accurately register US and MR images of the carotid artery, allowing multimodal analysis of the carotid plaque to improve plaque assessment.     

Arthroscopic Ultrasound Technique for Simultaneous Quantitative Assessment of Articular Cartilage and Subchondral Bone: An In Vitro and In Vivo Feasibility Study

Traditional arthroscopic examination is subjective and poorly reproducible. Recently, we introduced an arthroscopic ultrasound method for quantitative diagnostics of cartilage lesions. Here we describe our investigation of the feasibility of ultrasound arthroscopy for simultaneous measurements of articular cartilage and subchondral bone. Human osteochondral samples (n = 13) were imaged using a clinical 9-MHz ultrasound system. Ultrasound reflection coefficients (R, IRC), the ultrasound roughness index (URI) and the apparent integrated backscattering coefficient (AIB) were determined for both tissues. Mechanical testing, histologic analyses and micro-scale computed tomography imaging were the reference methods. Ultrasound arthroscopies were conducted on two patients. The ultrasound reflection coefficient correlated with the Mankin score and Young's modulus of cartilage (|r| > 0.56, p < 0.05). Ultrasound parameters (R, IRC, AIB) for subchondral bone correlated with the bone surface/volume ratio (|r| > 0.70, p < 0.05) and trabecular thickness (|r| > 0.59, p < 0.05). Furthermore, R and subchondral bone mineral density were significantly correlated (|r| > 0.65, p < 0.05). Arthroscopic ultrasound examination provided diagnostically valuable information on cartilage and subchondral bone in vivo.     

Quantitative Assessment of Articular Cartilage with Morphologic,Acoustic and Mechanical Properties Obtained Using High-Frequency Ultrasound

Osteoarthritis (OA) is one of the most common joint diseases among adults, and its early detection is still not possible. In this study, high-frequency ultrasound and ultrasound-assisted mechanical testing systems were used to quantitatively measure the morphologic, acoustic and mechanical properties of normal and enzymatically degraded bovine articular cartilages in vitro. A total of 40 osteochondral cartilage plugs were prepared from 20 bovine patellae (n = 20 × 2) and divided into two groups for collagenase and trypsin digestions, respectively. A high-frequency ultrasound system (center frequency: 40 MHz) was used to analyze the surface integrity (ultrasound roughness index, URI), thickness and acoustic properties of the articular cartilages before and after enzymatic degradations. Acoustic parameters included the integrated reflection coefficient (IRC) from the cartilage surface, reflection from the cartilage-bone interface (AIB_bone), integrated attenuation (IA) and integrated backscatter (IBS) of the internal cartilage tissue. A newly developed ultrasound water jet indentation system was used to assess the mechanical properties of the cartilage samples. The results showed that the URI increased significantly (p < 0.05) after collagenase digestion while no significant change (p > 0.05) was found after trypsin digestion. With regard to acoustic parameters, the IRC decreased significantly (p < 0.05) after collagenase digestion while no significant change (p > 0.05) was found after trypsin digestion. The AIB_bone demonstrated an insignificant change after collagenase digestion (p > 0.05) but a significant decrease after trypsin digestion (p < 0.05). Both enzymatic degradation groups showed insignificant differences (p > 0.05) in the IA but a significant increase (p < 0.05) in the IBS after both enzymatic degradations. The apparent stiffness measured by ultrasound water jet indentation suggested that articular cartilage from both groups became significantly softer (p < 0.05) after the enzymatic degradations. A significant relationship was found to exist between the IRC and URI (p < 0.05). This study showed that high-frequency ultrasound can be a comprehensive tool to quantitatively and systematically analyze the morphologic, acoustic and mechanical properties of articular cartilage in association with its degeneration. (E-mail: ypzheng@ieee.org)     

细胞因子联合激活人骨髓和外周血免疫细胞的比较研究

在本研究中比较了某些细胞因子在体外联合激活骨髓和外周血免疫细胞后二免疫细胞数量、形态、细胞化学染色、免疫表型和细胞毒变化的差异。在体外加入INF－γ，rIL-1，rIL-2和McAb-CD3分别激培养骨髓笔外周血单个核细胞，培养过程中观察两组免疫细胞增数量及形态的变化，培养前后两组取样进行细胞化学染色和有型检测，用MTT法检测培养后两组的细胞毒情况。研究结果发现，两组的细胞数量在激活培养后均较培养前明显增加，但外周血组增加倍数更多（P＜0．05）；细胞化学染色可见两组培养以后髓过氧化物酶积分均较培养前减少，过碘酸雪夫染色见两组含较多粗颗粒的淋巴样细胞明显较培养前多，两组CD3^ ，CD56^＋和CD38^ 细胞较培养前明显增加（P＜0．05），但两组增殖无明显差别；骨髓组培养后CD3^ CD56^ 细胞无明显增加，而外周血组培养后激活增加显（P＜0．05）；两组激活培养后细胞的细胞毒无明显差异，结论：rIL-γ，rIL-1，rIL-2和CD3单抗联合激活骨髓和外周血单个核细胞可使二细胞数量和细胞毒明显增加，在临床上可利用激活的不同来源的细胞因子诱导的杀伤细胞进行细胞免疫治疗。