A new ultrasound method for determining the acoustic phase shifts caused by the skull bone

A potential noninvasive means for obtaining the value of ultrasound (US) phase shifts caused by the skull is examined. Knowledge of these shifts could be used in new methods that restore the focus from an US array after transcranial propagation. In the present study, a pulsed signal was emitted from a single element of a therapeutic US transducer. The reflected signal was then recorded. The data were examined over the band width of the transducer, producing amplitude data as a function of frequency. A periodic appearance of local maxima and minima was observed in the data as a function of frequency. We hypothesize that the amplitude is primarily determined by the superposition of the reflections between the interfaces at the inner and outer surfaces of the skull and between the interior interfaces of trabecular and cortical bone. A homogeneous-layer model was used to predict the forward-propagated phase using the reflection data. Good correlation was found between the numeric calculation and phases measured after propagation through single-layer plastic plates. The method was used on curved three-layer plastic phantoms and four excised human skulls. The procedure could eventually be applied toward phasing multielement arrays. Such an application could have implications in both therapeutic and diagnostic brain procedures.     

单纯超声及超声结合理化因子的联合作用对细胞的生物效应

讨论了单纯超声和超声结合多种物理和化学因子(如射线、高热、化疗药物、光敏剂等)对正常和恶性细胞在离体和在体条件下的不同作用,并提出与单纯超声的细胞杀伤作用相比,超声和其他因子的联合作用更安全、更有效、针对性更高.综述了单纯超声、超声结合物理、化学因子的生物效应,以期为超声抗癌的进一步研究积累资料.     

Correlation of cavitation with ultrasound enhancement of thrombolysis

Pulsed ultrasound, when used as an adjuvant to recombinant tissue plasminogen activator (rt-PA), has been shown to enhance thrombolysis in the laboratory as well as in clinical trials for the treatment of ischemic stroke. The exact mechanism of this enhancement has not yet been elucidated. In this work, stable and inertial cavitation (SC and IC) are investigated as possible mechanisms for this enhancement. A passive cavitation detection scheme was utilized to measure cavitation thresholds at 120 kHz (80% duty cycle, 1667 Hz pulse repetition frequency) for four host fluid and sample combinations: plasma, plasma with rt-PA, plasma with clot and plasma with clot and rt-PA. Following cavitation threshold determination, clots were exposed to pulsed ultrasound for 30 min in vitro using three separate ultrasound treatment regimes: (1) no cavitation (0.15 MPa), (2) SC alone (0.24 MPa) or (3) SC + IC combined (0.36 MPa) in the presence of rt-PA. Percent clot mass loss after each treatment was used to determine thrombolysis efficacy. The highest percent mass loss was observed in the stable cavitation regime (26%), followed by the combined stable and inertial cavitation regime (20.7%). Interestingly, the percent mass loss in clots exposed to ultrasound without cavitation (13.7%) was not statistically significantly different from rt-PA alone (13%) [p > 0.05]. Significant enhancement of thrombolysis correlates with presence of cavitation and stable cavitation appears to play a more important role in the enhancement of thrombolysis. (E-mail: ).     

Schlieren study of pulsed ultrasound transmission through human skull

A study has been made of the effects of the human skull on pulsed ultrasound from a diagnostic transducer. Schlieren photographs of ultrasound transmitted through a pediatric skull were made in various directions. Other than attenuation, little effect was observed on the directionality or spatial distribution of the ultrasonic pulses. These observations may be significant in considering the deleterious effects of the skull on imaging intracranial anatomy.     

胎儿畸形与羊水过多的超声相关性研究

目的探讨胎儿畸形与羊水过多之间的相关性,并对造成羊水过多的常见胎儿畸形进行排序。方法分析13351例16～40孕周的胎儿资料,比较羊水正常组胎儿畸形发生率与羊水过多组中畸形发生率,并对羊水过多组中胎儿畸形种类进行统计排序。结果超声检出羊水过多103例,发现胎儿畸形26例,畸形发生率约25.2%;正常羊水量组13248例,其中胎儿畸形31例,胎儿畸形发生率约2.3%。羊水过多组中最常见胎儿畸形依次为:中枢神经系统畸形(26.9%)、骨骼畸形(23.1%)、消化系统畸形(15.4%)。结论超声检查是判断羊水过多的首选方法,羊水过多合并胎儿畸形的发生率明显高于正常羊水量组。其常见的畸形种类依次为中枢神经系统畸形、骨骼畸形和消化系统畸形。     

Longitudinal and shear mode ultrasound propagation in human skull bone

Recent studies have attempted to dispel the idea of the longitudinal mode being the only significant mode of ultrasound energy transport through the skull bone. The inclusion of shear waves in propagation models has been largely ignored because of an assumption that shear mode conversions from the skull interfaces to the surrounding media rendered the resulting acoustic field insignificant in amplitude and overly distorted. Experimental investigations with isotropic phantom materials and ex vivo human skulls demonstrated that, in certain cases, a shear mode propagation scenario not only can be less distorted, but at times allowed for a substantial (as much as 36% of the longitudinal pressure amplitude) transmission of energy. The phase speed of 1.0-MHz shear mode propagation through ex vivo human skull specimens has been measured to be nearly half of that of the longitudinal mode (shear sound speed = 1500 +/- 140 m/s, longitudinal sound speed = 2820 +/- 40 m/s), demonstrating that a closer match in impedance can be achieved between the skull and surrounding soft tissues with shear mode transmission. By comparing propagation model results with measurements of transcranial ultrasound transmission obtained by a radiation force method, the attenuation coefficient for the longitudinal mode of propagation was determined to between 14 Np/m and 70 Np/m for the frequency range studied, while the same for shear waves was found to be between 94 Np/m and 213 Np/m. This study was performed within the frequency range of 0.2 to 0.9 MHz.     

Low-frequency, low-intensity ultrasound accelerates thrombolysis through the skull.

Systemic thrombolysis of acute ischemic stroke with recombinant tissue plasminogen activator (rt-PA) has been established recently. Whereas the delay to and the rate of vessel recanalization are unknown, they are likely slower and smaller than for local application of rt-PA. This may contribute to the small benefits of recovery reported and stimulate further investigations to improve clot lysis. Pilot studies indicate that continuous-wave low-frequency ultrasound (US) can accelerate rt-PA-mediated recanalization of peripheral thrombotic vessel occlusion. For the hypothesized therapeutical purpose in stroke treatment, we measured the attenuation of ultrasound through the skull at different frequencies and intensities (33.3 and 71.4 kHz; 0.5 and 3.4 W/cm2), and investigated thrombolysis in vitro (n = 125 clots). Attenuation was lowest by transtemporal insonation of 33.3 kHz, 0.1 dB (0.9). Thrombolysis (artificial fibrin-rich clots) was significantly increased after 1 h (p < 0.025) and after 3 h (p < 0.01) for US treatment in combination with rt-PA vs. rt-PA alone. Results suggest that US increases rt-PA-mediated thrombolysis through the skull and may improve benefits of thrombolytic stroke treatment in vivo.     

不同回声类型颈动脉斑块超声造影增强强度的分析

目的分析超声造影显示斑块内增强的程度与常规超声斑块回声强度之间的关系。方法颈动脉粥样硬化患者135例,其中双侧颈动脉病变的患者32例,共167个颈动脉斑块。所有患者超声造影检查时仪器参数设置保持一致。常规超声上将颈动脉斑块的回声分为低、中、混合及强回声4种类型。超声造影观察斑块内有无增强并将斑块增强的程度人为分为0～4级。定量分析计算动脉斑块内增强强度及斑块内增强强度与颈动脉管腔内增强强度的比值。结果不同回声类型颈动脉斑块超声造影增强分级的强度间差异有统计学意义(χMH=47.4,P<0.0001),斑块回声越低超声造影增强越明显。低回声斑块中有75.6%(31/41)达2级以上增强,而部分中等回声及混合斑块超声造影也可表现为明显增强,2级以上增强分别占56.8%(25/44)及62.3%(38/61)。强回声斑块则只有1个(1/21,4.8%)表现为2级增强。低、中、混合、强回声颈动脉斑块的超声造影增强强度分别为(4.33±3.34)dB、(3.71±3.40)dB、(3.16±2.56)dB、(0.96±0.37)dB,增强强度比值分别为0.24±0.17、0.21±0.17、0.19±0.13、0.06±0.02。不同回声类型颈动脉斑块的超声造影定量分析参数增强强度(t=7.75,P<0.0001)及增强强度比值(t=4.49,P<0.0001)的差异均有统计学意义,斑块回声越低,超声造影定量分析增强越显著,呈线性相关。结论超声造影可在常规超声评价斑块回声强弱的基础上提供更多关于斑块稳定性的信息,有助于对患者的筛选,进而采取合适的干预措施。     

原发性骨质疏松症患者胸椎后凸角度与躯体功能的相关性研究

目的:通过评定原发性骨质疏松症患者胸椎后凸角度、躯干屈伸肌群肌力、平衡功能和心肺功能,探讨骨质疏松症患者胸椎后凸角度与躯体功能的相关性。方法:原发性骨质疏松症女性53例,年龄54—84岁。评定胸椎后凸Cobb角、腰背肌肌力、腹直肌肌力、平衡功能(睁眼、闭眼单足站立时间和起立-行走计时测试时间)和心肺功能(胸廓扩张度和6min行走试验距离)并进行相关性分析。结果:本组患者胸椎Cobb角为17.2°—68.0°(平均[42.1±14.6]°)。Cobb角分别与腰背肌肌力(r=-0.452)、6min行走试验距离(r=-0.419)和睁眼单足站立时间(r=-0.299)呈负相关;Cobb角与腹直肌肌力、闭眼单足站立时间、胸廓扩张度和起立-行走计时测试时间无相关性。结论:原发性骨质疏松症患者胸椎后凸角度与腰背肌肌力、静态平衡功能和心肺功能负相关,与腹直肌肌力、胸廓扩张度和功能性活动能力无明显相关。因此,对于胸椎后凸角度越大的骨质疏松症患者越应加强上述受累躯体功能的评定与康复训练。     

颈动脉粥样硬化与肾动脉狭窄的相关性研究

目的 探讨冠状动脉粥样硬化患者颈动脉粥样硬化与肾动脉狭窄的相关性。方法 对54例冠状动脉造影患者的颈动脉行超声检查,并对照其肾动脉及冠状动脉血管造影检查结果,经单因素χ^2检验,研究其相关性。结果 冠状动脉粥样硬化患者伴颈动脉粥样硬化者肾动脉狭窄的发病率高于无颈动脉粥样硬化者,而且,颈动脉粥样硬化越重,肾动脉狭窄的发病率越高,狭窄程度也越重。结论 冠状动脉粥样硬化患者颈动脉粥样硬化与肾动脉狭窄密切相关。     

健康体检中腹部超声检查的应用价值

目的探讨腹部超声在健康体检中的应用价值。方法统计5000例健康体检者腹部脏器的各种疾病在各年龄阶段的患病数及患病率。结果通过腹部超声检查发现无临床症状的腹部疾病发病率逐渐增加,如脂肪肝、胆囊息肉、胆结石、肾结石、子宫肌瘤等。结论健康人群超声检查可发现早期恶性肿瘤,为临床治疗提供最佳时机并具有简便、无创伤、快速及筛选等功能,应作为体检的必检项目。     

Translabial ultrasound of the third-trimester uterine cervix. Correlation with digital examination

This prospective blinded study compared translabial ultrasound (TLU) and digital palpation of the cervix among women whose cervix could not be visualized adequately or at all with transabdominal ultrasound during the third trimester of pregnancy. The cervical canal and internal cervical os were adequately visualized during 109 of 113 TLUs (96%). The TLU was well tolerated by the patients; only two patients refused the TLU pending discussion of the technique with their obstetrician. Among 43 examinations of patients without clinical cervical effacement, TLU showed a cervical length of 2.5 to 4.2 cm (mean, 2.9 cm). An excellent correlation (R = 0.90) was noted between cervical length on TLU and percentage of cervical effacement on digital examination. The correlation between amount of cervical dilatation on TLU and on digital examination was not high (R = 0.58). We conclude that the measurements of cervical length on TLU correlate well with the amount of cervical effacement on digital examination and that TLU provides a rapid and well-tolerated alternative technique to visualize the third-trimester uterine cervix.     

低频超声联合微泡经颅开放血脑屏障初步研究

目的探讨低频超声联合微泡经颅靶向开放血脑屏障及在临床应用价值。方法①经静脉注射微泡后,用频率为43kHz、强度为2W/cm2,持续超声波辐射大鼠头部5min;②采用荧光显微镜伊文氏蓝(EB)、电镜镧示踪法以及透射电镜观察脑组织的超微结构变化。结果经颅超声波与微泡联合能短暂地促进伊文氏蓝和镧离子通过多种形式跨越血脑屏障。结论低频超声联合微泡能可逆的、靶向的、局部的开放血脑屏障,并为进一步研究药物进入脑实质内提供新的策略。     

Acoustic properties of lesions generated with an ultrasound therapy system

Methods for quantitative imaging of ultrasound propagation properties were applied to the examination of the acoustic appearance of lesions generated by high intensity focused ultrasound in excised pig livers. Single lesions, about 10 mm maximum diameter by 30 mm long, were created in each of six liver specimens. Two dimensional images (32 by 32 points) of sound speed, mean attenuation coefficient (as a function of frequency in the range 3 to 8.5 MHz) and mean backscattering coefficient (5 to 8 MHz) were obtained in 7 mm thick sections of tissue, cut to include a cross-section through the lesion. Images of these properties, presented alongside surface photographs of the samples, provided a qualitative demonstration that attenuation coefficient was the most useful and backscattering coefficient was the least useful acoustic parameter for visualizing such lesions. Quantitatively the data demonstrated significant increases in attenuation coefficient and sound speed in lesioned liver relative to normal, whereas backscattering was shown not to change in a significant manner except when undissolved gas is the mechanism for increased acoustic scattering. Samples where gas was not fully removed following lesion production gave significant increases in backscattering at the lesion centre, but the shape and size of regions of high backscattering coefficient corresponded poorly with the shape and size of the lesions, unlike attenuation and sound speed for which such correspondence was good.     

卵巢肿瘤超声造影定量参数与微血管密度的相关性研究

目的探讨卵巢良恶性肿瘤超声造影定量参数与肿瘤组织中微血管密度(MVD)的相关性。方法选取经病理确诊的卵巢肿瘤患者48例,共计51个病灶,依据术后病理结果可分为良性组24个、恶性组27个,应用超声造影测量评价两组血流灌注的定量参数:峰值强度(IMAX)、上升时间、达峰时间、平均渡越时间及时间-强度曲线下面积(AUC),同时对其病理组织行免疫组化染色及MVD计数,分析各造影定量参数与MVD计数的相关性。结果恶性组IMAX及AUC分别为24.72±5.15、1940.97±565.96,高于良性组(7.53±5.90和397.57±299.46),差异均有统计学意义(均P<0.05),其他参比较差异无统计学意义;恶性组MVD计数为32.5±10.4,明显高于良性组(12.7±4.4),差异有统计学意义(P<0.05);两组IMAX及AUC分别与MVD呈正相关(r=0.42,P=0.009;r=0.57,P=0.008),其他参数无相关性。结论卵巢肿瘤超声造影定量参数与MVD存在相关性,可术前无创性评估卵巢肿瘤的血管生成。     

Influence of organic phase change materials on the physical and mechanical properties of HDPE and PP polymers

In this work, the compatibility of four commercially available organic phase change materials, with melting points in the temperature range 44–58 °C and with engineering polymers high density polyethylene (HDPE) and polypropylene (PP), is investigated. These polymers are used for the design and manufacture of hot and cold thermal energy storage tanks or encapsulation media. The study involves interaction of polymer specimens with the four different phase change materials for a period of time up to 40 days under high temperature. The mass change, mechanical strength and properties of the polymers were tested. The wt% uptake reached 6.4 wt% for PP and 5.8 wt% for HDPE. The strength of HDPE is immediately decreased by Day 7 but at a significant level restored after Day 28. No such effect was found for PP. The surface wetting as well as thermal properties measured (DSC) on the specimens provided an insight on the interaction of the absorbed phase change materials with the polymer. An in depth distribution over time was observed with significant decrease in the mechanical strength of the polymers. An epoxy-based resin was also evaluated under the same conditions and is suggested as a protective coating.

Organic PCMs affect HDPE and PP mechanical properties. HDPE strength is remarkably partly restored by the homogeneous distribution of absorbed PCM.     

Influence of ultrasound and physical activity on bone healing

The aim of this study was to investigate the effects of ultrasound treatment of experimental bone fractures and the effects of physical exercise on the speed of bone consolidation. Osteotomy was performed on the upper third of the right tibia of rats. Physical training consisted of swimming 1 h per d with a load of 5% body weight and therapy with medium-intensity ultrasound was applied for 5 min daily. Young adult male Wistar rats were divided into four groups: (1) osteotomized sedentary animals with no ultrasound treatment (OSnUS); (2) trained with no ultrasound treatment (OTnUS); (3) sedentary with ultrasound treatment (OSwUS); and (4) trained with ultrasound treatment (OTwUS). The animals were sacrificed for the following analyses: muscle glycogen and serum alkaline phosphatase on the 5(th), 10(th), 20(th) and 30(th) days and histological slices of the bone on the 5(th) and 20(th) days. The results show that ultrasound is better in the initial phases of the process of bone tissue repair and physical exercise at the end of bone consolidation. These facts suggest that the treatments herein used prove favorable to the bone regenerative process, as the overall ossification process has been accelerated. (E-mail: marceloguerino@hotmail.com).     

同期手术治疗外伤性颅骨缺损合并脑积水14例疗效观察

目的 探讨外伤性颅骨缺损合并交通性脑积水患者同期手术的疗效.方法 14例颅骨缺损合并脑积水患者均采用同期手术治疗,术中先行颅骨缺损修补,然后行脑室-腹腔分流术,脑室穿刺点选择在颅骨缺损处.修补额部时穿刺前角,修补颞部时穿刺三角区,缝合腹部切口时应用皮肤缝合线阻断分流管,术后第7天开放分流管.结果 全组患者颅骨塑型满意,无感染及皮下积液等并发症发生;脑积水患者术前表情淡漠、尿失禁或夜尿多等现象,术后均改善或消失;原脑室扩大均有不同程度缩小.结论 颅骨缺损合并交通性脑积水患者同期手术效果良好.     

Effects of physical parameters on high temperature ultrasound hyperthermia

The purpose of this research was to investigate the feasibility of inducing perfusion independent, predictable therapeutic thermal dose using high power ultrasonic pulses. Computer simulations were used to study the effects of blood perfusion, tissue properties, transducer characteristics, and treatment geometry on the temperature elevation and thermal dose delivered by short ultrasonic pulses. Experiments were conducted in vitro and in vivo to investigate the effects of blood perfusion changes. Results show that short pulse lengths (less than or equal to 2 s) and small focal diameters (approximately 3 mm) give temperature elevations and thermal doses which are nearly perfusion independent. Normal fluctuations in tissue properties should not have a significant effect on the treatment provided that proper choice of transducer is made for each individual application.