High-Frequency Ex vivo Ultrasound Imaging of the Auditory System

A 50 MHz array-based imaging system was used to obtain high-resolution images of the ear and auditory system. This previously described custom built imaging system (3, 4 and 2) is capable of 50 μm axial resolution, and lateral resolution varying from 80 μm to 130 μm over a 5.12 mm scan depth. The imaging system is based on a 2 mm diameter, seven-element equal-area annular array, and a digital beamformer that uses high-speed field programmable gate arrays (FPGAs). The images produced by this system have shown far superior depth of field compared with commercially available single-element systems. Ex vivo, three-dimensional (3-D) images were obtained of human cadaveric tissues including the ossicles (stapes, incus, malleus) and the tympanic membrane. In addition, two-dimensional (2-D) images were obtained of an intact cochlea by imaging through the round window membrane. The basilar membrane inside the cochlea could clearly be visualized. These images demonstrate that high-frequency ultrasound imaging of the middle and inner ear can provide valuable diagnostic information using minimally invasive techniques that could potentially be implemented in vivo. (E-mail: J.Brown@dal.ca)     

Validation of minimally invasive, image-guided cochlear implantation using Advanced Bionics, Cochlear, and Medel electrodes in a cadaver model

Purpose

Validation of a novel minimally invasive, image-guided approach to implant electrodes from three FDA-approved manufacturers—Medel, Cochlear, and Advanced Bionics—in the cochlea via a linear tunnel from the lateral cranium through the facial recess to the cochlea.

Methods

Custom microstereotactic frames that mount on bone-implanted fiducial markers and constrain the drill along the desired path were utilized on seven cadaver specimens. A linear tunnel was drilled from the lateral skull to the cochlea followed by a marginal, round window cochleostomy and insertion of the electrode array into the cochlea through the drilled tunnel. Post-insertion CT scan and histological analysis were used to analyze the results.

Results

All specimens ( $N=7$ ) were successfully implanted without visible injury to the facial nerve. The Medel electrodes ( $N=3$ ) had minimal intracochlear trauma with 8, 8, and 10 (out of 12) electrodes intracochlear. The Cochlear lateral wall electrodes (straight research arrays) ( $N=2$ ) had minimal trauma with 20 and 21 of 22 electrodes intracochlear. The Advanced Bionics electrodes ( $N=2$ ) were inserted using their insertion tool; one had minimal insertion trauma and 14 of 16 electrodes intracochlear, while the other had violation of the basilar membrane just deep to the cochleostomy following which it remained in scala vestibuli with 13 of 16 electrodes intracochlear.

Conclusions

Minimally invasive, image-guided cochlear implantation is possible using electrodes from the three FDA-approved manufacturers. Lateral wall electrodes were associated with less intracochlear trauma suggesting that they may be better suited for this surgical technique.     

In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography

Sound transduction within the auditory portion of the inner ear, the cochlea, is a complex nonlinear process. The study of cochlear mechanics in large rodents has provided important insights into cochlear function. However, technological and experimental limitations have restricted studies in mice due to their smaller cochlea. These challenges are important to overcome because of the wide variety of transgenic mouse strains with hearing loss mutations that are available for study. To accomplish this goal, we used spectral domain optical coherence tomography to visualize and measure sound-induced vibrations of intracochlear tissues. We present, to our knowledge, the first vibration measurements from the apex of an unopened mouse cochlea.OCIS codes: (170.4500) Optical coherence tomography, (170.4940) Otolaryngology     

Acoustic Output Measured by Thermal and Mechanical Indices during Fetal Echocardiography at the Time of the First Trimester Scan

We measured acoustic output, expressed as the thermal index (TI) and mechanical index (MI), during fetal echocardiography at the time of the first trimester scan. TI and MI were retrieved from the saved displays during gray-mode, high-definition color flow Doppler and pulsed-wave Doppler (tricuspid flow) ultrasound examinations of the fetal heart and from the ductus venosus assessment. A total of 399 fetal cardiac examinations were evaluated. There was a significant increase in TI values from B-mode studies (0.07 ± 0.04 [mean ± SD]) to color flow mapping (0.2 ± 0.0) and pulsed-wave Doppler studies (0.36 ± 0.05). The TI from ductus venosus assessment (0.1 ± 0.01) was significantly lower than those from Doppler examinations of the heart. MI values from B-mode scans (0.65 ± 0.12) and color flow mapping (0.71 ± 0.11) were comparable, although different, and both values were higher than those from pulsed-wave Doppler tricuspid evaluation (0.39 ± 0.03). There were no differences in MI values from power Doppler assessment between the tricuspid flow and ductus venosus. Safety indices were remarkably stable and were largely constant, especially for color Doppler (TI), tricuspid flow (MI) and ductus venosus assessment (TI, MI). We acquired satisfactory Doppler images and/or signals at acoustic levels that were lower than the actual recommendations and never reached a TI of 0.5.     

Application of pulsed-wave Doppler ultrasound to exploration of the peripheral vasomotor response by gender and hand dominance

Purpose  

Laser Doppler flowmetry measures peripheral vasomotor response but fails to detect changes in vascular diameters, resistance, and heart rates. Because this response contributes to assessing sympathetic disorders and relies on the above variables to be correctly interpreted, we used pulsed-wave Doppler (PWD) ultrasound to evaluate the response and to determine whether it was affected by gender or hand dominance.     

High-frequency ultrasound Doppler system for biomedical applications with a 30-MHz linear array

In this paper, we report the development of the first high-frequency (HF) pulsed-wave Doppler system using a 30-MHz linear array transducer to assess the cardiovascular functions in small animals. This array-based pulsed-wave Doppler system included a 16-channel HF analog beamformer, a HF pulsed-wave Doppler module, timing circuits, HF bipolar pulsers and analog front ends. The beamformed echoes acquired by the 16-channel analog beamformer were fed directly to the HF pulsed-wave Doppler module. Then the in-phase and quadrature-phase (IQ) audio Doppler signals were digitized by either a sound card or a Gage digitizer and stored in a personal computer. The Doppler spectrogram was displayed on a personal computer in real time. The two-way beamwidths were determined to be 160 microm to 320 microm when the array was electronically focused at different focal points at depths from 5 to 10 mm. A micro-flow phantom, consisting of a polyimide tube with an inner diameter of 127 microm and the wire phantom were used to evaluate and calibrate the system. The results show that the system is capable of detecting motion velocity of the wire phantom as low as 0.1 mm/s, and detecting blood-mimicking flow velocity in the 127-microm tube lower than 7 mm/s. The system was subsequently used to measure the blood flow in vivo in two mouse abdominal superficial vessels, with diameters of approximately 200 microm, and a mouse aorta close to the heart. These results demonstrated that this system may become an indispensable part of the current HF array-based imaging systems for small animal studies.     

Ouabain诱导沙鼠蜗外电诱发听性脑干反应变化研究

目的沙鼠耳蜗圆窗应用毒毛旋花甙G(Ouabain),观察沙鼠蜗外电诱发听性脑干反应(EABR)的变化。方法显微镜下将浸有50μl Ouabain(1 mM)的明胶海绵置于沙鼠耳蜗圆窗膜表面,观察应用Ouabain 24 h、96 h后听觉脑干反应(ABR)、耳蜗微音电位(CM)、蜗外电诱发听性脑干反应(EABR)阈值变化。结果沙鼠圆窗应用Ouabain 24h、96 h后ABR、EABR阈值明显升高,差异具有统计学意义(P<0.05),CM阈值无明显变化,差异无统计学意义(P>0.05)。结论沙鼠圆窗膜表面应用50μl Ouabain(1 mM)24 h、96 h后可导致沙鼠ABR、EABR阈值明显升高,而CM阈值无明显变化。     

Measurement of the Doppler Power of Flowing Blood Using Ultrasound Doppler Devices

Measurement of the Doppler power of signals backscattered from flowing blood (henceforth referred to as the Doppler power of flowing blood) and the echogenicity of flowing blood have been used widely to assess the degree of red blood cell (RBC) aggregation for more than 20 y. Many studies have used Doppler flowmeters based on an analogue circuit design to obtain the Doppler shifts in the signals backscattered from flowing blood; however, some recent studies have mentioned that the analogue Doppler flowmeter exhibits a frequency-response problem whereby the backscattered energy is lost at higher Doppler shift frequencies. Therefore, the measured Doppler power of flowing blood and evaluations of RBC aggregation obtained using an analogue Doppler device may be inaccurate. To overcome this problem, the present study implemented a field-programmable gate array-based digital pulsed-wave Doppler flowmeter to measure the Doppler power of flowing blood, in the aim of providing more accurate assessments of RBC aggregation. A clinical duplex ultrasound imaging system that can acquire pulsed-wave Doppler spectrograms is now available, but its usefulness for estimating the ultrasound scattering properties of blood is still in doubt. Therefore, the echogenicity and Doppler power of flowing blood under the same flow conditions were measured using a laboratory pulser–receiver system and a clinical ultrasound system, respectively, for comparisons. The experiments were carried out using porcine blood under steady laminar flow with both RBC suspensions and whole blood. The experimental results indicated that a clinical ultrasound system used to measure the Doppler spectrograms is not suitable for quantifying Doppler power. However, the Doppler power measured using a digital Doppler flowmeter can reveal the relationship between backscattering signals and the properties of blood cells because the effects of frequency response are eliminated. The measurements of the Doppler power and echogenicity of flowing blood were compared with those obtained in several previous studies.     

Cochlear gene delivery through an intact round window membrane in mouse

Cochlear gene transfer studies in animal models have utilized mainly two delivery methods: direct injection through the round window membrane (RWM) or intracochlear infusion through a cochleostomy. However, the surgical trauma, inflammation, and hearing loss associated with these methods lead us to investigate a less invasive delivery method. Herein, we studied the feasibility of a vector transgene-soaked gelatin sponge, Gelfoam, for transgene delivery into the mouse cochlea through an intact RWM. The Gelfoam absorbed with liposomes and adenovirus, but not with adeno-associated virus (AAV), was successful in mediating transgene expression across an intact RWM in a variety of cochlear tissues. The Gelfoam technique proved to be an easy, atraumatic, and effective, but vector-dependent, method of delivering transgenes through an intact RWM. Compared with the more invasive gene delivery methods, this technique represents a safer and a more clinically viable route of cochlear gene delivery in humans.     

Preliminary use of endoluminal ultrasonography in assessment of middle ear with effusion.

Endoluminal ultrasonography with small-caliber and high-frequency transducer is suitable for transcanal assessment of middle ear with effusion. An endoluminal ultrasound transducer (size 6 French, 20 MHz) with a side-viewing scanning plane was used to image 12 ears of six children suspected of having effusion in the middle ear. Sonographic findings were compatible with those of operation in 10 diseased ears. One false-negative result was obtained, and one trial was aborted owing to trauma to the canal wall. The present study proves utility in demonstrating fluid behind the tympanic membrane. A promising use of endoluminal ultrasonography for middle ear evaluation might be expected if some modification could be made to the transducer.     

Investigation of middle ear anatomy and function with combined video otoscopy-phase sensitive OCT

We report the development of a novel otoscopy probe for assessing middle ear anatomy and function. Video imaging and phase-sensitive optical coherence tomography are combined within the same optical path. A sound stimuli channel is incorporated as well to study middle ear function. Thus, besides visualizing the morphology of the middle ear, the vibration amplitude and frequency of the eardrum and ossicles are retrieved as well. Preliminary testing on cadaveric human temporal bone models has demonstrated the capability of this instrument for retrieving middle ear anatomy with micron scale resolution, as well as the vibration of the tympanic membrane and ossicles with sub-nm resolution.OCIS codes: (170.4940) Otolaryngology, (110.4500) Optical coherence tomography, (120.5050) Phase measurement, (120.7280) Vibration analysis     

A robot-guided minimally invasive approach for cochlear implant surgery: preliminary results of a temporal bone study

Purpose  The aim of this study was to create an access canal to the inner ear, by drilling, and perform the cochleostomy for cochlear implant surgery using robot guidance. Methods  A robot, a surgical drill and an Image-Guided Surgery (IGS) system were combined in a closed-loop setup. Ten temporal bones were scanned at the planning stages of the procedure. The robot guided the drill along the preplanned trajectory and created the approach. Postoperative scans were obtained. Results  The cochleostomy was performed completely in nine out of ten cases. This did not prove possible for one of the specimens, the target site selected being in too superficial a location in relation to the round window. No violation of the facial nerve took place, although the chorda tympani nerve was violated in one case and the stapes in two. It was obvious during preoperative planning that these structures would be violated, but this was accepted in order to maintain a safety margin from the facial nerve. No other unforeseen damage occurred. Conclusions  This preliminary study suggests that robot-guided drilling of a minimally invasive approach to the cochlea might be feasible, but further improvements are necessary before any clinical application becomes possible. Where the width of the facial recess is less than 2.5 mm, the chorda tympani nerve and the ossicles are at risk. Source of financial support or funding: Deutsche Forschungsgemeinschaft (DFG-German Research Foundation), Priority Program 1124 (Medical Robotics).     

先天性小耳畸形颞骨HRCT诊断

目的：探讨先天性小耳畸形颞骨HRCT表现。方法：分析54例66耳先天性小耳畸形患者的颞骨HRCT影像，观察颞骨各部的异常表现。结果：64耳（97．0％）有骨性外耳道狭窄或闭锁；51耳（77．3％）鼓室狭窄或闭锁；58耳（87．9％）听骨链发育畸形或缺如；11耳（16．7％）卵圆窗缺如或部分缺如；3耳（4．5％）圆窗缺如；6耳（9.1%）内耳畸形；9耳（13．6％）面神经鼓室段走向异常；36耳（54．5％）面神经乳突段前移；20耳（30．3％）为高位颈静脉球；10耳（15．2％）表现为乙状窦前位；23耳（34．8％）中颅窝低位。结论：先天性小耳畸形颞骨HRCT多表现为骨性外耳道及鼓室的狭窄或闭锁、听骨链发育畸形或缺如、面神经乳突段前移，此外卵圆窗缺如或部分缺如、面神经鼓室段走向异常、高位颈静脉球、乙状窦前位、中颅窝低位亦不少见，而内耳畸形、圆窗闭锁少见。     

HRCT诊断外伤性颞骨内耳损伤

目的 探讨HRCT诊断外伤性颞骨内耳损伤的价值。方法 对106例颞骨外伤患者进行HRCT轴位扫描,收集其中内耳损伤患者12例。应用Philips工作站,行颞骨（耳蜗、前庭、水平半规管、前半规管、后半规管） MPR并观察内耳损伤位置、类型及其相邻结构受累的情况。结果 12例内耳损伤患者中,内耳骨折8例,气迷路3例,耳蜗异物1例;3例合并外伤性迷路骨化。结论 HRCT扫描及MPR重建技术可清晰显示内耳受损情况,是诊断内耳损伤的有效方法。     

Cerumen Occlusion Lowers Infrared Tympanic Membrane Temperature Measurement

Objective: To examine the effect that cerumen occlusion of the ear canal has on infrared tympanic membrane temperature measurement.
Methods: A prospective, randomized, single-blind human study was carried out in a university hospital observation unit. The subjects were a convenience sample of human volunteers aged 18 years or older who did not have cerumen occlusion or scarred tympanic membranes. A paraffin-coated human cerumen plug was placed in one randomly chosen ear, and after 20 minutes of equilibration the temperature in each ear was measured with an infrared thermometer. Analysis of the difference in mean temperature between the occluded and nonoccluded ears was by Student's paired t-test.
Results: Infrared tympanic membrane temperatures were measured in 43 subjects aged 21 to 58 years. The mean temperature of the occluded ear canal was 0.3°C lower than that of the opposite ear canal (p = 0.0001, 95% CI 0.16–0.45°C).
Conclusion: Cerumen occlusion of the ear canal causes underestimation of body temperature measured by infrared tympanic membrane thermometry.     

Activation of the GABA(A) receptor ameliorates the cochlear excitotoxicity caused by kainic acid in the guinea pig

Excitotoxicity is a major neurotoxic mechanism in cochlear disorders, including cochlear ischemic injury and acoustic injury. Kainic acid (KA), an excitatory amino acid, can damage glutamatergic neurons. The application of KA to the round window membrane, an opening of the cochlear bony labyrinth to the middle ear, induces excitotoxicity of cochlear afferent dendrites and significantly decreases the amplitude of compound action potential of the cochlea (CAP), a cochlear potential generated by activation of the auditory nerve fibers. On the other hand, muscimol, a gamma-aminobutyric acid (GABA)(A) receptor agonist, is neuroprotective in excitotoxicity in the central nervous system. Here we studied whether activation of GABA receptor decreased the excitotoxicity of the cochlea caused by KA. KA (10 mM) was applied to the round window membrane of guinea pigs for 30 minutes. Muscimol, bicuculline, a GABA(A) receptor antagonist, or baclofen, a GABA(B) receptor agonist, was given at the onset of KA application. The threshold shift of CAP was examined with chronically implanted electrodes. Application of KA significantly elevated the CAP threshold on day 1 and day 3 as compared with the pre-application level. Muscimol significantly decreased the KA-induced CAP threshold shifts. Furthermore, this protective effect of muscimol was inhibited by the application of bicuculline, a GABA(A) receptor antagonist. However, baclofen, a GABA(B) receptor agonist, did not affect the CAP threshold shifts caused by KA. These results suggest that activation of GABA(A) receptor could prevent cochlear excitotoxicity. GABA(A) receptor activation may represent an effective treatment of cochlear ischemic injury and acoustic injury.     

高频超声诊断孤立性小腿肌间静脉血栓的价值

目的探讨高频超声对孤立性小腿肌间静脉血栓的诊断价值。方法回顾性分析临床确诊的175例（190条）孤立性小腿肌间静脉血栓的声像图特征并与临床随访结果进行对比分析。结果 175例（190条）孤立性小腿肌间静脉血栓,高频超声正确诊断158例（173条）,误诊7例（7条）,漏诊10例（10条）,诊断准确率91.1%（173/190）。误诊7例分别为神经纤维瘤1例,混合型血管瘤1例,腓肠肌血肿5例。所有患者发现后均进行溶栓及抗凝治疗,治疗后1、3、6个月复查彩色多普勒超声,血流部分再通或完全再通,均无小腿深静脉主干蔓延。小腿肌间静脉血栓声像图特征：静脉管腔明显增宽,管腔内低回声充填,长轴呈管状或树枝状,短轴为圆形或椭圆形,适度加压管腔不能被压瘪,管腔内大多无血流信号显示。结论高频彩色多普勒超声可以显示血栓的位置、形态、类型、管腔阻塞情况及血流状态,有助于明确诊断孤立性小腿肌间静脉血栓,同时对治疗效果可以进行动态评估。     

Topical application of the antiapoptotic TAT-FNK protein prevents aminoglycoside-induced ototoxicity

We previously demonstrated that an artificial protein, TAT-FNK, has antiapoptotic effects against cochlear hair cell (HC) damage caused by ototoxic agents when applied systemically. To examine the feasibility of topical protein therapy for inner ear disorders, we investigated whether gelatin sponge soaked with TAT-FNK and placed on the guinea pig round window membrane (RWM) could deliver the protein to the cochlea and attenuate aminoglycoside (AG)-induced cochlear damage in vivo. First, we found that the immunoreactivity of TAT-myc-FNK was distributed throughout the cochlea. The immunoreactivity was observed from 1-24 h after application. When Tat-FNK was applied 1 h before ototoxic insult (a combination of kanamycin sulfate and ethacrynic acid), auditory brainstem response threshold shifts and the extent of HC death were significantly attenuated. When cochlear organotypic cultures prepared from P5 rats were treated with kanamycin, TAT-FNK significantly reduced the extent of caspase-9 activation and HC death. These findings indicate that TAT-FNK topically applied on the RWM can enter the cochlea by diffusion and effectively prevent AG-induced apoptosis of cochlear HCs by suppressing the mitochondrial caspase-9 pathway.     

Ultrasound in anesthesia: applying scientific principles to clinical practice

The use of ultrasound as an adjunct to invasive anesthesia procedures is becoming commonplace. The U.S. Agency for Health Care Quality and the United Kingdom National Institute for Clinical Excellence have identified the role of ultrasound in improving patient safety. Numerous studies have demonstrated the benefits of ultrasound, yet there have also been articles inferring it may not offer additional benefits to traditional landmark techniques. The major disadvantage often cited is that success is user-dependent, and using ultrasound is a unique skill that requires training and experience to become proficient. Modern ultrasound systems incorporate 2 sound technologies to provide users with specific information about what is being viewed. Brightness mode imaging and pulsed-wave Doppler can be combined to reduce potential complications associated with central venous access and regional anesthesia. Human tissue is also an important factor in ultrasound imaging. The different densities of soft tissues, bone, fluid, and air all interact with sound, creating distinctive images that can aid and potentially hinder accuracy. Comprehension of basic ultrasound principles and how it is affected by tissue will enable anesthetists to better understand what is being seen and reduce the potential for errors.     

膝关节滑膜炎的高频彩色多普勒超声图像特征及其诊断分析

目的:通过研究高频彩色多普勒超声对于膝关节滑膜炎的图像特征进行分析,探索高频彩色多普勒超声的诊断价值。方法:采集2018年3月-2019年9月在本院进行治疗的60名膝关节滑膜炎患者,分别采用X线片、核磁共振、高频彩色多普勒超声对患者进行检测,比较三种检测方法的检测结果,并分析高频彩色多普勒超声检查膝关节滑膜炎的声像图特点。结果:高频彩色多普勒超声对膝关节滑膜炎具有很好的分辨率;X线片、核磁共振、高频彩色多普勒超声三种检测方法比较,与X线片检测的各项数据相比有统计显著性(P<0.05),与MRI检测的各项数据相比无统计学意义(P>0.05)。结论:高频彩色多普勒超声对显示滑膜形态、滑膜厚度、关节腔积液、软骨病变等具有很好的效果,且简单无创、准确率高,适用于临床膝关节滑膜炎的临床检测。