Device failure caused by the dissociation of floating mass transducer in Vibrant SoundBridge®.

BACKGROUND: Vibrant SoundBridge® (VSB), a semi-implantable middle ear device, is one of the treatment options for patients with mild-to-severe sensorineural hearing loss or mixed hearing loss. Herein, we report delayed device failure after VSB surgery in two patients. CASE PRESENTATION: In both cases, a revision surgery was performed for the removal of the device; dissociation of the floating mass transducer (FMT) and coupler was noticed in one patient, and dissociation of the FMT-coupler complex from the short process of the incus in the other. In Case 1, the vibration-like sounds disappeared after the surgery. In Case 2, wearing bilateral hearing aids improved hearing after removal surgery, but complaints regarding speech discrimination persisted. Both cases show the importance of not loosening the connectivity between the FMT, coupler, and short process of the incus during VSB surgery. CONCLUSIONS: To our knowledge, there has been no report of dissociation from the short process of the incus or the dissociation between an FMT and the coupler.

Safety of ultrasonic examinations; thermal and mechanical indices.

This review article combines the reports on the biophysical effects in ultrasonography and provides the rationale behind the mechanical index (MI) and thermal index (TI) complying with the Output Display Standard (ODS). Safe ultrasonic doses are determined according to specific rules, and the screen displays the associated quantities MI and TI. The introduced indices MI and TI take into account the physical mechanism of interaction between ultrasounds and biological tissue, which depends on the temporal and spatial parameters of the acoustic field generated by ultrasound transducers. The predicted temperature increase is determined using three different tissue models: homogeneous, layered and bone/tissue interface.

Combined radiotherapy and concurrent tumor treating fields (TTFields) for glioblastoma: Dosimetric consequences on non-coplanar IMRT as initial results from a phase I trial.

BACKGROUND: Glioblastoma is a rapidly proliferating tumor. Patients bear an inferior prognosis with a median survival time of 14-16 months. Proliferation and repopulation are a major resistance promoting factor for conventionally fractionated radiotherapy. Tumor-Treating-Fields (TTFields) are an antimitotic modality applying low-intensity (1-3 V/cm), intermediate-frequency (100-300 kHz) alternating electric-fields. More recently interference of TTFields with DNA-damage-repair and synergistic effects with radiotherapy were reported in the preclinical setting. This study aims at examining the dosimetric consequences of TTFields applied during the course of radiochemotherapy. METHODS: Cone-beam-computed-tomography (CBCT)-data from the first seven patients of the PriCoTTF-phase-I-trial were used in a predefined way for dosimetric verification and dose-accumulation of the non-coplanar-intensity-modulated-radiotherapy (IMRT)-treatment-plans as well as geometric analysis of the transducer-arrays by which TTFields are applied throughout the course of treatment. Transducer-array-position and contours were obtained from the low-dose CBCT's routinely made for image-guidance. Material-composition of the electrodes was determined and a respective Hounsfield-unit was assigned to the electrodes. After 6D-fusion with the planning-CT, the dose-distribution was recalculated using a Boltzmann-equation-solver (Acuros XB) and a Monte-Carlo-dose-calculation-engine. RESULTS: Overdosage in the scalp in comparison to the treatment plan without electrodes stayed below 8.5% of the prescribed dose in the first 2 mm below and also in deeper layers outside 1cm2 at highest dose as obtained from dose-volume-histogram comparisons. In the clinical target volume (CTV), underdosage was limited to 2.0% due to dose attenuation by the electrodes in terms of D95 and the effective-uniform-dose. Principal-component-analysis (PCA) showed that the first principal-position-component of the variation of repeated array-placement in the direction of the largest variations and the perpendicular second-component spanning a tangential plane on the skull had a standard deviation of 1.06 cm, 1.23 cm, 0.96 cm, and 1.11 cm for the frontal, occipital, left and right arrays for the first and 0.70 cm, 0.71 cm, 0.79 cm, and 0.68 cm, respectively for the second-principal-component. The variations did not differ from patient-to-patient (p > 0.8, Kruskal-Wallis-tests). This motion led to a diminution of the dosimetric effects of the electrodes. CONCLUSION: From a dosimetric point of view, dose deviations in the CTV due to transducer-arrays were not clinically significant in the first 7 patients and confirmed feasibility of combined adjuvant radiochemotherapy and concurrent TTFields. PriCoTTF Trial: A phase I/II trial of TTFields prior and concomitant to radiotherapy in newly diagnosed glioblastoma. DRKS-ID: DRKS00016667. Date of Registration in DRKS: 2019/02/26. Investigator Sponsored/Initiated Trial (IST/IIT): yes. Ethics Approval/Approval of the Ethics Committee: Approved. (leading) Ethics Committee Nr.: 18-8316-MF, Ethik-Kommission der Medizinischen. Fakultät der Universität Duisburg-Essen. EUDAMED-No. (for studies acc. to Medical Devices act): CIV-18-08-025247.

Swedish Sonographers' perceptions of ergonomic problems at work and their suggestions for improvement.

BACKGROUND: Sonographers' perceptions of ergonomic and work-related pain problems at work have so far mostly been researched in quantitative studies by questionnaires. There is a need of experience-based research to deepen the knowledge about how sonographers perceive ergonomic problems at work. Therefore, the aim of this qualitative study was to describe sonographers' perceptions of ergonomic problems at work, and their suggestions for improvement strategies. METHODS: Twenty-two female sonographers were individually interviewed regarding different aspects of their physical working environment. Content analysis was applied. RESULTS: The sonographers perceived different ergonomic problems in their working environment, but to offer patient comfort and to obtain the best possible images were often prioritized over working posture. Echocardiography was considered demanding as the examination is performed with little variation in posture. Ergonomic improvements included reducing the manual handling of the transducer, optimizing the adjustability of equipment, and taking the patient's physique and health into account. As some examinations were perceived to be more ergonomically demanding, variation between examinations was suggested, however, this requires broader skills. CONCLUSION: Sonography, especially echocardiography is ergonomically demanding but the improvement strategies suggested were perceived useful and applicable.

Wireless Ultrasound Guidance for Femoral Venous Cannulation in Electrophysiology: Impact on Safety, Efficacy, and Procedural Delay.

BACKGROUND: Ultrasound (US) guidance increases safety and efficacy in vascular cannulation and is considered the standard of care. However, barriers including workflow interference and the need to be assisted by a second operator limit its adoption in clinical routine. The use of wireless US (WUS) may overcome these barriers. The aim of this study was to assess the impact of a novel WUS probe during its initial implantation in an electrophysiology (EP) laboratory. METHODS: Thirty-six patients requiring femoral venous cannulation for EP procedures were included in this single center, prospective, observational study, comparing WUS guidance with the anatomical landmark approach. The primary endpoint was time to successful cannulation. Secondary endpoints included rate of unsuccessful punctures, accidental arterial punctures, and workflow interference. RESULTS: Compared with anatomical landmark approach, WUS guidance significantly reduced mean time to successful cannulation (87.3 ± 94.3 vs 238.1 ± 294.7 seconds, P < 0.01). Workflow interference was predominantly nonexistent or mild and decreased after the first three weeks of use. In addition, WUS guidance improved safety and efficacy, reducing the rate of accidental arterial punctures (0.02 ± 0.1 vs 0.25 ± 0.5 arterial punctures per cannulation, P < 0.05) and unsuccessful attempts (0.26 ± 0.8 vs 1.75 ± 2.1 attempts per cannulation, P < 0.01). CONCLUSIONS: WUS guidance resulted in faster, safer, and more effective femoral venous cannulation than the anatomical landmark approach without adding significant workflow interference. The application of wireless technology in this setting contributed to overcoming some of the barriers preventing a more widespread clinical use of US guidance.

In vitro analysis of pyrogenicity and cytotoxicity profiles of flex sensors to be used to sense human joint postures.

Flex sensors can be usefully adopted as mechanical-electrical transducers to measure human joint movements, since their electrical resistance varies proportionally to the angle assumed by the joint under measure. Over time, these sensors have been investigated in terms of mechanical and electrical behavior, but no reports have detailed the possibility of their adoption not just on top but under the human skin of the joint. To this aim, our work investigated in vitro the pyrogenic potential and cytotoxicity of some commercially available flex sensors as a first step toward the necessary requirements regarding their biocompatibility, to predict possible foreign body reactions when used in vivo. Results demonstrated that some specific flex sensors satisfy such requirements.

Comparison of comfort and image quality with two endorectal coils in MRI of the prostate.

PURPOSE: To prospectively evaluate comfort and image quality of prostate MRI using two different endorectal (ER) coils. MATERIALS AND METHODS: Thirty consecutive patients were prospectively randomized to receive prostate MRI using either a prostate endocoil (PEC) or colorectal endocoil (CEC). Patients and operators were surveyed with regard to endocoil placement. Four Body MRI trained radiologists rated image quality for each examination and additional selected blinded coronal T2 weighted images. RESULTS: Average patient discomfort (on a 0-10 pain scale) was greater with the PEC (5.0 for PEC and 2.7 for CEC) with a statistically significant difference (P < 0.03). Ability to identify the neurovascular bundle (NVB) was 5.8 times more likely to be rated excellent with the CEC compared with the PEC (P < 0.003). Image quality with CEC was 3.5 times more highly rated (P < 0.04). In particular, signal-to-noise ratio (SNR) with the CEC was 3.0 times more highly rated than with the PEC (P < 0.05). CONCLUSION: The smaller CEC was better tolerated by patients than the traditional PEC, and resulted in at least equivalent, and in some instances improved image quality. This may result in fewer aborted cases and lead to decreased procedural intolerance to endorectal coil MRI.

Are ultrasound-guided ophthalmic blocks injurious to the eye? A comparative rabbit model study of two ultrasound devices evaluating intraorbital thermal and structural changes.

BACKGROUND: Since Atkinson's original description of retrobulbar block in 1936, needle-based anesthetic techniques have become integral to ophthalmic anesthesia. These techniques are unfortunately associated with rare, grave complications such as globe perforation. Ultrasound has gained widespread acceptance for peripheral nerve blockade, but its translation to ocular anesthesia has been hampered because sonic energy, in the guise of thermal or biomechanical insult, is potentially injurious to vulnerable eye tissue. The US Food and Drug Administration (FDA) has defined guidelines for safe use of ultrasound for ophthalmic examination, but most ultrasound devices used by anesthesiologists are not FDA-approved for ocular application because they generate excessive energy. Regulating agencies state that ultrasound examinations can be safely undertaken as long as tissue temperatures do not increase >1.5°C above physiological levels. METHODS: Using a rabbit model, we investigated the thermal and mechanical ocular effects after prolonged ultrasonic exposure to single orbital- and nonorbital-rated devices. In a dual-phase study, aimed at detecting ocular injury, the eyes of 8 rabbits were exposed to continuous 10-minute ultrasound examinations from 2 devices: (1) the Sonosite Micromaxx (nonorbital rated) and (2) the Sonomed VuMax (orbital rated) machines. In phase I, temperatures were continuously monitored via thermocouples implanted within specific eye structures (n = 4). In phase II the eyes were subjected to ultrasonic exposure without surgical intervention (n = 4). All eyes underwent light microscopy examinations, followed at different intervals by histology evaluations conducted by an ophthalmic pathologist. RESULTS: Temperature changes were monitored in the eyes of 4 rabbits. The nonorbital-rated transducer produced increases in ocular tissue temperature that surpassed the safe limit (increases >1.5°C) in the lens of 3 rabbits (at 5.0, 5.5, and 1.5 minutes) and cornea of 2 rabbits (both at 1.5 minutes). A secondary analysis of temporal temperature differences between the orbital-rated and nonorbital transducers revealed statistically significant differences (Bonferroni-adjusted P < 0.05) in the cornea at 3.5 minutes, the lens at 2.5 minutes, and the vitreous at 4.0 minutes. Light microscopy and histology failed to elicit ocular injury in either group. CONCLUSIONS: The nonorbital-rated ultrasound machine (Sonosite Micromaxx) increases the ocular tissue temperature. A larger study is needed to establish safety. Until then, ophthalmic ultrasound-guided blocks should only be performed with ocular-rated devices.

Design and characterization of a laterally mounted phased-array transducer breast-specific MRgHIFU device with integrated 11-channel receiver array.

PURPOSE: This work presents the design and preliminary evaluation of a new laterally mounted phased-array MRI-guided high-intensity focused ultrasound (MRgHIFU) system with an integrated 11-channel phased-array radio frequency (RF) coil intended for breast cancer treatment. The design goals for the system included the ability to treat the majority of tumor locations, to increase the MR image's signal-to-noise ratio (SNR) throughout the treatment volume and to provide adequate comfort for the patient. METHODS: In order to treat the majority of the breast volume, the device was designed such that the treated breast is suspended in a 17-cm diameter treatment cylinder. A laterally shooting 1-MHz, 256-element phased-array ultrasound transducer with flexible positioning is mounted outside the treatment cylinder. This configuration achieves a reduced water volume to minimize RF coil loading effects, to position the coils closer to the breast for increased signal sensitivity, and to reduce the MR image noise associated with using water as the coupling fluid. This design uses an 11-channel phased-array RF coil that is placed on the outer surface of the cylinder surrounding the breast. Mechanical positioning of the transducer and electronic steering of the focal spot enable placement of the ultrasound focus at arbitrary locations throughout the suspended breast. The treatment platform allows the patient to lie prone in a face-down position. The system was tested for comfort with 18 normal volunteers and SNR capabilities in one normal volunteer and for heating accuracy and stability in homogeneous phantom and inhomogeneous ex vivo porcine tissue. RESULTS: There was a 61% increase in mean relative SNR achieved in a homogeneous phantom using the 11-channel RF coil when compared to using only a single-loop coil around the chest wall. The repeatability of the system's energy delivery in a single location was excellent, with less than 3% variability between repeated temperature measurements at the same location. The execution of a continuously sonicated, predefined 48-point, 8-min trajectory path resulted in an ablation volume of 8.17 cm(3), with one standard deviation of 0.35 cm(3) between inhomogeneous ex vivo tissue samples. Comfort testing resulted in negligible side effects for all volunteers. CONCLUSIONS: The initial results suggest that this new device will potentially be suitable for MRgHIFU treatment in a wide range of breast sizes and tumor locations.

What to do if a transesophageal echocardiography probe buckled in esophagus?

A 65-year-old man was consulted because of buckling of transesophageal echocardiography (TEE) probe in the esophagus. A forward-viewing endoscope was inserted to the esophagus alongside the TEE probe. TEE probe was pushed to the stomach while the retroflexed tip portion was pushed by the endoscope in order to prevent retroflexion. The TEE probe was advanced into the stomach by this method where the buckled part was unfolded and then withdrawn. Cardiologists performing TEE and the referred gastroenterologists could perform such a method of solution in case of buckling of TEE probe in the esophagus.

Improvement of contractile function in isolated cardiomyocytes from ischemia-reperfusion rats by ginkgolide B pretreatment.

Ginkgo biloba extract is an important natural product for treatment of cerebral and cardiovascular diseases, whereas ginkgolide B (GB) is a main component of it. Its effects on ischemic heart and ventricular contractile function in Sprague-Dawley male rats are unclear yet. In the present study, we investigated the function of isolated hearts subjected to ischemia-reperfusion (IR) with or without GB pretreatment by using Millar transducer instruments. We also tested the left ventricular cardiomyocyte shortening amplitude after IR with different concentrations of GB pretreatment for 0.1, 1.0, 2.0, 5.0, and 10.0 microM. The infarct size was tested by triphenyltetrazolium chloride. The release of lactate dehydrogenase (LDH) in the coronary effluent was determined with LDH kit. The expressions of Bcl-2 and Bax were assessed by Western blotting. We found that GB improved the function of left ventricle from IR injury and decreased infarct size and the release of LDH. The cardiomyocyte shortening amplitude depended on different concentrations of GB, which increased significantly at 2.0 microM GB (P < 0.01). The expression of protein Bcl-2 was upregulated by GB and the ratio of Bax to Bcl-2 was decreased by GB. Our results showed that GB can partly prevent IR injury in rat heart.

Incidence of cardiac arrhythmias with therapeutic versus diagnostic ultrasound and intravenous microbubbles.

OBJECTIVE: The purpose of this study was to determine the type of arrhythmias induced with therapeutic versus diagnostic transthoracic low-frequency ultrasound (TLFUS) transducers in the presence of intravenous microbubbles. METHODS: Intravenous perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles were infused or given as a bolus injection while TLFUS was applied in the standard parasternal and apical views with either a 1-MHz therapeutic ultrasound transducer or high-mechanical-index diagnostic ultrasound (1.7 MHz). RESULTS: Significantly more ectopy was produced by the therapeutic transducer, especially at higher-intensity settings in the continuous wave mode after bolus injections of PESDA (P < .001 compared with lower intensities and lower continuous infusion rates). Six patients (15%) had either clinical supraventricular tachycardia or nonsustained ventricular tachycardia after intravenous PESDA with therapeutic TLFUS. In comparison, diagnostic high-mechanical-index ultrasound produced only isolated ventricular ectopy and no sustained ventricular arrhythmias. CONCLUSIONS: Intravenously injected microbubbles and low-frequency therapeutic transducers operating at longer duty cycles and wide beam widths have the capability of eliciting clinically important arrhythmias in patients at high risk for such events.

FasL deficiency enhances the development of tumors in p53+/- mice.

In the multistep process of tumor development, several events occur to transform cells from normal to malignant. Although p53 is one of the most commonly mutated genes in a wide variety of tumors, how other genes interact with p53 to transform cells is only just beginning to be understood. To study the effects of the interaction of the Fas system with p53 in tumor progression and development, mice with a targeted disruption of the p53 tumor supressor gene and a mutation in Fas ligand were bred. Organ weights, life expectancy, and tumor and tissue histology were assessed. Although spleen weights were drastically increased in FasL -/- p53 -/- mice, the FasL deficiency had no effect on life expectancy or the tumor spectrum of homozygous p53-deficient mice. The FasL deficiency reduced the median time to death from 12.1 months in FasL +/+ p53 +/- mice to 9.6 months in FasL -/- p53 +/- mice, and led to a shift in tumor spectrum from predominantly sarcomas (63%) when FasL was present to a large number of lymphomas (76%) in FasL -/- p53 +/- mice. Given the reduced life span and increased incidence of lymphoma in FasL -/- p53 +/- mice, these mice could be useful in carcinogenicity testing, particularly for understanding mechanisms of compounds that are nongenotoxic.

Transponder-induced sarcoma in the heterozygous p53+/- mouse.

Heterozygous p53+/- transgenic mice are being studied for utility as a short-term alternative model to the 2-yr rodent carcinogenicity bioassay. During a 26-wk study to assess the potential carcinogenicity of oxymetholone using p-cresidine as a positive control, glass/polypropylene microchips (radio transponder identification devices) were subcutaneously implanted into male and female p53+/- mice. During week 15, the first palpable mass was clinically observed at an implant site. This rapidly growing mass virtually quadrupled in size by week 25. Microscopic examination of all implant sites revealed that 18 of 177 animals had a subcutaneous histologically malignant sarcoma. The neoplasms were characterized as undifferentiated sarcomas unrelated to drug treatment, as indicated by the relatively even distribution among dose groups, including controls. An unusual preneoplastic mesenchymal change characterized by the term "mesenchymal dysplasia" was present in most groups and was considered to be a prodromal change to sarcoma development. The tumors were observed to arise from dysplastic mesenchymal tissue that developed within the tissue capsule surrounding the transponder. The preneoplastic changes, including mesenchymal dysplasia, appeared to arise at the transponder's plastic anchoring barb and then progressed as a neoplasm to eventually surround the entire microchip. Capsule membrane endothelialization, inflammation, mesenchymal basophilia and dysplasia, and sarcoma were considered unequivocal preneoplastic/neoplastic responses to the transponder and were not related to treatment with either oxymetholone or p-cresidine.

The feasibility of elastographic visualization of HIFU-induced thermal lesions in soft tissues. Image-guided high-intensity focused ultrasound.

The potential for visualizing high-intensity focused ultrasound (HIFU)-induced thermal lesions in biological soft tissues in vitro using elastography was investigated. Thermal lesions were created in rabbit paraspinal skeletal muscle in vivo. The rabbits were sacrificed 60 h following the treatment and lesioned tissues were excised. The tissues were cast in a block of clear gel and elastographic images of the lesions were acquired. Gross pathology of the tissue samples confirmed the characteristics of the lesions.

Transesophageal echocardiography and monitoring applications.

Transesophageal echocardiography (TEE) is a widely used cardiac imaging technique that provides the clinician with a view of the heart as seen from the esophagus or stomach. Rapid advances in TEE transducer technology, coupled with the low-risk, semi-invasive nature of the procedure, have fueled its use for cardiac monitoring of surgical and critical care patients, in addition to diagnostic imaging. Many recent research studies have demonstrated the utility of TEE for direct, real-time evaluation of global and regional left ventricular function not achievable with current competing technologies at the bedside. As a result of these advantages, TEE has become an emerging tool in cardiac monitoring at many centers around the world.