Ultrasound properties of liver tissue during heating

The objective of this work was to determine changes in the ultrasound properties of heated tissues, with potential application to monitoring of minimally invasive thermal therapy (MITT). Changes in backscatter coefficients and frequency-dependent attenuation coefficients were measured over the frequency range 2.5 MHz to 5 MHz from heated samples of store-bought fresh bovine liver, which was used as a tissue model. Individual liver samples were heated from 37°C to either 50°C, 55°C, 60°C, 65°C or 70°C by warm water. The backscatter coefficient increased during the first 3 min by a factor of 1.09 and 1.11 before the tissue reached 50°C and 55°C, respectively. A decrease in backscatter coefficient followed at 50°C by a factor of 1.12 below the initial level and, at 55°C, the backscatter coefficient dropped below the initial level by a factor of 1.19. The backscatter coefficient decreased within the first 2 min by a factor of 1.22 before the tissue reached 60°C, then increased gradually to a factor of 1.05 below the initial level. At 65°C and 70°C, the changes in backscatter coefficient were highly variable, which may have been due to production of gas microbubbles in the heated tissues. The ultrasound attenuation coefficient increased by as much as 1.48 dB cm⁻¹ over a 30-min period at 70°C. First-order rate parameters derived from the attenuation results revealed one rate process at 50°C and 55°C and two rate processes at 60°C, 65°C and 70°C. An activation energy of 1.00 × 10⁴ cal mol⁻¹ was derived from the second rate constants at 60°C, 65°C and 70°C, which indicates that changes in attenuation may be due to protein denaturation. In conclusion, ultrasound image monitoring of thermal therapy treatment in liver may be feasible; however, the backscatter coefficient changes during heating are small and are of the same order as the variation in these changes from point to point in the tissue.     

Ultrasound properties of human prostate tissue during heating

Changes in the ultrasound (US) properties of tissue during heating affect the delivery of US thermal therapy and may provide a basis for US image monitoring of thermal therapy. The US attenuation coefficient and backscatter power of fresh human prostate tissue were measured as the tissue was heated. Samples of human prostate were obtained directly from autopsies and heated rapidly to final temperatures of 45 degrees C, 50 degrees C, 55 degrees C, 60 degrees C and 65 degrees C. A 5.0-MHz transducer was scanned in a raster pattern over the tissue and radiofrequency (RF) data were collected at 36 uncorrelated positions. Both attenuation and backscatter were measured over the frequency range 3.5 to 7.0 MHz at each min of a 30-min heating. Little change was observed in attenuation or backscatter at 55 degrees C or less. The attenuation coefficient and backscatter power increased by factors of 1.25 and 5, respectively, during the 60 degrees C heating. During the 65 degrees C heating, the same properties showed increases by factors of 2.7 and 9.     

Bone microstructure and elastic tissue properties are reflected in QUS axial transmission measurements

Accurate clinical interpretation of the sound velocity derived from axial transmission devices requires a detailed understanding of the propagation phenomena involved and of the bone factors that have an impact on measurements. In the low megahertz range, ultrasonic propagation in cortical bone depends on anisotropic elastic tissue properties, porosity and the cortical geometry (e.g., thickness). We investigated 10 human radius samples from a previous biaxial transmission study using a 50-MHz scanning acoustic microscope (SAM) and synchrotron radiation microcomputed tomography. The relationships between low-frequency axial transmission sound speed at 1 and 2 MHz, structural properties (cortical width Ct.Wi, porosity, Haversian canal density and material properties (acoustic impedance, mineral density) on site-matched cross-sections were investigated. Significant linear multivariate regression models (1 MHz: R(2) = 0.84, p < 10(-4), root-mean-square error (RMSE) = 38 m/s, 2 MHz: R(2) = 0.65, p < 10(-4), RMSE = 48 m/s) were found for the combination of Ct.Wi with porosity and impedance. A new model was derived that accounts for the nonlinear dispersion relation with Ct.Wi and predicts axial transmission velocities measured at different ultrasonic frequencies (R(2) = 0.69, p < 10(-4), RMSE = 52 m/s).     

Ultrasound measurements of fetal limb bones.

In order to establish the growth patterns of fetal limbs, measurements of femur, humerus, tibia, fibula, radius and ulna were made by ultrasound and related to gestational age. To this end, 2317 normal singleton pregnant women were studied cross-sectionally at 13-40 weeks of gestation. Patients were selected on the basis of a certain last menstrual period, history of regular cycles and at least one ultrasound scan before 16 weeks confirming gestational age. Linear growth of all limb measurements was observed between 13 and 28 weeks of gestation. From this gestational age onwards, a flattening of the growth curve was seen. A second-degree polynomial equation turned out to be the best model to describe this phenomenon. The measurements of all six fetal long bones showed a high correlation with menstrual age (r >or= 0.99). The femur displayed the largest mean weekly increments (2.8 mm per week from 13 to 28 weeks and 1.7 mm per week from 29 to 40 weeks of gestation) and the radius had the smallest (2.08 mm per week from 13 to 28 weeks and 1.25 mm per week from 29 to 40 weeks' gestation). Considering inter and intraoperator variations and the weekly increment of fetal long bone length, a correct evaluation of limb growth is possible for the femur every week before 28 weeks and every 2 weeks after 28 weeks. For the remaining limb bones, a correct evaluation is possible every 2 weeks at all gestational ages.     

超声评估血管外肺水

血管外肺水(EVLW)是评估肺水肿的重要指标,与死亡率独立相关,积极治疗可改善患者预后.CT和MRI可准确评估肺水肿,但不适用于实时监测;而单次热稀释需要重复校准,易出错.由于空气的高声阻抗,传统上认为肺部不适于超声检查.超声B线是识别EVLW及观察其动态变化的灵敏方法,伴随研究的深入,超声越来越多地用于评估EVLW,...     

Ultrasound of the lung: just imagine

Intensive Care Medicine -     

Simulation of lung tissue properties in age and irreversible obstructive syndromes using an aldehyde.

Weak solutions of CHOH alter tissue properties, probably by forming intermolecular cross-linkages. The maximum length (Lmax) to which alveolar wall can be extended is reduced. If exposed to CHOH while extended, the resting length (LO) of alveolar wall increases. Maximum extensibility (Lambdamax equal to Lmax/LO) decreases. Similar changes are found in the alveolar wall of man with aging and are significantly more marked in patients with irreversible obstructive pulmonary syndromes. A reduction in the energy loss of the length-tension cycle (hysteresis) was seen after exposure to CHOH, however, that does not occur with age or in obstructive syndromes. Because an exposure of alveolar wall to elastase increases LO and hysteresis, we used a staged exposure to CHOH followed by elastase. Tissue suitably prepared by exposure to CHOH followed by elastolysis better simulates the tissue changes of age and irreversible obstructive syndromes.     

Apoprotein measurements and their clinical application

The apoproteins structurally are closely associated with specific lipoproteins, for example, apoprotein B with VLDL and LDL and apoprotein A-I with HDL. The levels of these apoproteins provide information about the plasma concentrations and metabolism of the lipoproteins with which they are associated. The levels of apoprotein B and apoprotein A-I and the Lp(a) lipoprotein can serve as important predictors of coronary heart disease risk and can provide information not available from blood lipid and lipoprotein lipid levels. For clinicians and public health interests, the decision to use apoprotein measurements and to estimate cardiovascular risk depends on the clinical setting, the availability of standardized apoprotein methods that can be related to age- and sex-specific population-based reference values, and the cost of the measurements. In addition, these apoproteins can be used in specific cases to answer diagnostic questions and provide information about therapeutic response.     

Ultrasound propagation speed in arthritic synovial tissue

Ultrasonic properties of knee synovial tissues destroyed by arthritis were studied by analysing 40 tissue specimens from 21 patients using an ultrasound echo meter and an optical microscope. The idea was to compare pathological findings to ultrasound propagation speeds, and to try to find any relation between them. The fresh specimens were first measured by the echo meter to collect data for statistical calculations of the propagation speed vs. different pathological properties. Before pathological studies, the specimens were fixed in formalin solution. The connective and fat tissues were evaluated within a resolution of 5% and expressed in percentages (0–100%). Inflammatory cells, edema and villus formation were also evaluated. As results, we obtained several charts of ultrasound propagation speed and their trends in the function of different properties. It could be seen that the trend of the propagation speed increased from 1515 m/s to 1565 m/s when the percentage amount of connective tissue increased from 30% to 90%. The trend of the speed decreased from 1560 m/s to 1480 m/s when the share of fat tissue increased from 0 to 60%. The same phenomenon is already well known from some other tissues. A special new result was that the speed varied in a remarkable range of 1490–1660 m/s in samples of 0% fat and high connective tissue content. The overall average of the ultrasound propagation speed in the specimens was 1548 m/s, and the average of the standard deviations of measurements (each specimen was measured at least twice) of each tissue specimen was 8.3 m/s.     

Ultrasound tissue characterization of breast biopsy specimens.

Results of measurements of ultrasound speed and absorption coefficients in the range 3 to 8 MHz in breast tissues at 37 C are reported and analyzed in attempts to identify a set of ultrasound parameters capable of discriminating normal, benign, and malignant tissues. We analyzed 118 tissue regions, comprising 47 normal, 55 benign, and 16 malignant by straight-line fitting of frequency dependence of attenuation. Data for ten additional regions, for a total of 128, became available and were added to the cohort when we subsequently fitted quadratic curves. Sound speed consistently emerged as the variable with greatest discriminating power, particularly for separating normal from benign and malignant tissue. Great difficulty was encountered in discriminating benign from malignant, even when the jackknife technique was used. More success was found with classification and regression trees (CART), although results were sensitive to assigned misclassification costs. Best results from straight-line fits were obtained when discriminating malignant from combined normal/benign data after randomly assigning 75 percent of the data to the learning set and 25 percent to the test set. Then, 23 out of 25 normal/benign and 4 out of 4 malignant cases in the test set were correctly classified. With quadratic fitting, best results were obtained in the three-class case--the false positive rate for malignancy was reduced to zero in the learning (0/31) and test (0/10) sets. Nevertheless, the false negative rate increased to 13 out of 31 (42 percent) in the learning set, while attaining zero (0/4) in the test set.     

超声引导经皮肺肿物穿刺自动活检术的临床价值

目的 探讨超声引导经皮肺肿物穿刺自动活检方法及其临床应用价值。方法 采用B型超声仪对40例肺肿块术前体表定位，确定穿刺线路，术中在超声实时监测下应用自动活检枪配套切割式活检针进行穿刺活检，术后观察并发症。结果 40例均取材成功。病理诊断35例为肺癌，3例为炎性假瘤，2例为结核球，均可确诊。穿刺后无一例出现气胸、出血等并发症。结论 超声实时引导经皮肺穿刺自动活检是一种安全、准确、经济的确诊外周部肺肿物的方法。     

超声在肺部疾病诊断中的应用

近年来,肺部超声成像受到广泛关注,其临床价值得到认可。本文就肺部超声的成像原理、常见征象和临床应用作一综述。     

Ultrasound measurements in early pregnancy (author's transl)]

With the aid of the ultrasound scan technique the amniotic sac was measured on more than 700 occasions between the 8th and 20th week of gestation. In each examination the greatest transverse, anterior-posterior and longitudinal diameters were determined. The statistical mean and the double standard deviation were calculated from these data. The areas of the transverse diameter and of the longitudinal diameter show a distinct and continuous increase, whilst the area of the anterior-posterior diameter displays a small and uncharacteristic increase during pregnancy. The values of 12 patients were registered in the region of the transverse and of the longitudinal diameter. The clinical findings, as well as the ultrasonic values, had shown no abnormalities at that time. The data show a decrease in these diameters during the following examinations; the last measurement was carried out when the fetal heart beat was absent for the first time. The increase in size of the amniotic sac during pregnancy can be observed by means of these examinations. Repeated examinations enable the detection of disturbances in the developement of the pregnancy at an early stage.