Sonication in the diagnosis of fracture-related infections (FRI)-a retrospective study on 230 retrieved implants.

BACKGROUND: In fracture-related infections (FRI), both the diagnosis of the infection and the identification of the causative pathogen are crucial to optimize treatment outcomes. Sonication has been successfully used for periprosthetic joint infections (PJI); however, its role in FRI remains unknown. Our aim was to determine the diagnostic accuracy (sensitivity, specificity) of sonicate fluid culture (SFC). The primary objective was to compare SFC with peri-implant tissue culture (PTC) overall and among subgroups using the consensus definition by Metsemakers et al. The secondary objective was to determine the yield of SFC in possible fracture-related infections (PFRI). METHODS: From March 2017 to May 2019, 230 cases of retrieved implants were retrospectively reviewed. To perform sonication, explants were placed in sterile polypropylene jars intraoperatively. After treatment in an ultrasonic bath (Bandelin, Berlin, Germany), sonicate fluid was incubated into blood culture bottles, and conventional culturing was eventually performed. Sensitivity and specificity were determined using two-by-two contingency tables. McNemar's test was used to compare proportions among paired samples while Fisher's exact test was used for comparison between categorical variables. RESULTS: Of the 230 cases, 107 were identified as FRI, whereas 123 were aseptic revision cases (ARC). Of the latter, 105 were labeled as PFRI. Sensitivity of SFC was higher in comparison with PTC, although this did not reach statistical significance (90.7% vs. 84.1%; p = .065). The specificity of SFC was significantly lower than that of PTC (73.2% vs. 88.6%; p = .003). In PFRI, SFC yielded significantly more positive results than PTC (33/105 vs. 14/105; p = .003). Overall, 142 pathogens were identified by SFC, whereas 131 pathogens were found by PTC. CONCLUSIONS: We found that sonication of fracture fixation devices may be a useful adjunct in FRI, especially in "low-grade" infections lacking confirmatory clinical criteria. Standardized diagnostic protocols are warranted in order to further optimize the diagnostic accuracy.

Implant Sonication versus Tissue Culture for the Diagnosis of Spinal Implant Infection.

MINI: We compared the sensitivity and specificity of peri-implant tissue culture to the vortexing-sonication technique for the diagnosis of spinal implant infection (SII). Lower thresholds of sonicate fluid culture positivity showed increased sensitivity with maintained specificity. We recommend a threshold of 20 CFU/10 mL for sonicate culture positivity for the diagnosis of SII. STUDY DESIGN: This is a retrospective study comparing the diagnosis of spinal implant infection (SII) by peri-implant tissue culture to vortexing-sonication of retrieved spinal implants. OBJECTIVE: We hypothesized that vortexing-sonication would be more sensitive than peri-implant tissue culture. SUMMARY OF BACKGROUND DATA: We previously showed implant vortexing-sonication followed by culture to be more sensitive than standard peri-implant tissue culture for diagnosing of SII. In this follow-up study, we analyzed the largest sample size available in the literature to compare these two culture methods and evaluated thresholds for positivity for sonicate fluid for SII diagnosis. METHODS: We compared peri-implant tissue culture to the vortexing-sonication technique which samples bacterial biofilm on the surface of retrieved spinal implants. We evaluated different thresholds for sonicate fluid positivity and assessed the sensitivity and specificity of the two culture methods for the diagnosis of SII. RESULTS: A total of 152 patients were studied. With more than 100 colony forming units (CFU)/10 mL as a threshold for sonicate fluid culture positivity, there were 46 patients with SII. The sensitivities of peri-implant tissue and sonicate fluid culture were 65.2% and 79.6%; the specificities were 88.7% and 93.4%, respectively. With more than 50 CFU/10 mL as a threshold, there were 50 patients with SII. The sensitivities of peri-implant tissue and sonicate fluid culture were 68.0% and 76.0%; the specificities were 92.2% for both methods. Finally, with more than or equal to 20 CFU/10 mL as a threshold, there were 52 patients with SII. The sensitivities of peri-implant tissue and sonicate fluid culture were 69.2% and 82.7%; the specificities were 94.0% and 92.0%, respectively. CONCLUSION: Implant sonication followed by culture is a sensitive and specific method for the diagnosis of SII. Lower thresholds for defining sonicate fluid culture positivity allow for increased sensitivity with a minimal decrease in specificity, enhancing the clinical utility of implant sonication. LEVEL OF EVIDENCE: 4.

This is a retrospective study comparing the diagnosis of spinal implant infection (SII) by peri-implant tissue culture to vortexing­sonication of retrieved spinal implants. We hypothesized that vortexing­sonication would be more sensitive than peri-implant tissue culture. We previously showed implant vortexing­sonication followed by culture to be more sensitive than standard peri-implant tissue culture for diagnosing of SII. In this follow-up study, we analyzed the largest sample size available in the literature to compare these two culture methods and evaluated thresholds for positivity for sonicate fluid for SII diagnosis. We compared peri-implant tissue culture to the vortexing­sonication technique which samples bacterial biofilm on the surface of retrieved spinal implants. We evaluated different thresholds for sonicate fluid positivity and assessed the sensitivity and specificity of the two culture methods for the diagnosis of SII. A total of 152 patients were studied. With more than 100 colony forming units (CFU)/10 mL as a threshold for sonicate fluid culture positivity, there were 46 patients with SII. The sensitivities of peri-implant tissue and sonicate fluid culture were 65.2% and 79.6%; the specificities were 88.7% and 93.4%, respectively. With more than 50 CFU/10 mL as a threshold, there were 50 patients with SII. The sensitivities of peri-implant tissue and sonicate fluid culture were 68.0% and 76.0%; the specificities were 92.2% for both methods. Finally, with more than or equal to 20 CFU/10 mL as a threshold, there were 52 patients with SII. The sensitivities of peri-implant tissue and sonicate fluid culture were 69.2% and 82.7%; the specificities were 94.0% and 92.0%, respectively. Implant sonication followed by culture is a sensitive and specific method for the diagnosis of SII. Lower thresholds for defining sonicate fluid culture positivity allow for increased sensitivity with a minimal decrease in specificity, enhancing the clinical utility of implant sonication. Level of Evidence: 4.

Optimization of ultrasound-assisted water extraction of flavonoids from Psidium guajava leaves by response surface analysis.

Psidium guajava leaves are rich in health-promoting flavonoids compounds. For better utilization of the resource, the ultrasound-assisted aqueous extraction was investigated using Box-Behnken design under response surface methodology. A high coefficient of determination (R2 = 97.8%) indicated good agreement between the experimental and predicted values of flavonoids yield. The optimal extraction parameters to obtain the highest total flavonoids yield were ultrasonic power of 407.41 W, extraction time of 35.15 min, and extraction temperature of 72.69 °C. The average extraction rate of flavonoids could reach 5.12% under the optimum conditions. Besides, HPLC analysis and field emission scanning electron microscopy indicated that the ultrasonic treatment did not change the main component of flavonoids during extraction process and the higher flavonoids content was attributed by the disruption of the cell walls of guava particles. Thus, the extraction method could be applied successfully for large-scale extraction of total flavonoids from guava leaves.

A Novel, Optimized Method to Accelerate the Preparation of Injectable Poly-L-Lactic Acid by Sonication.

Current consensus for preparing injectable poly-L-lactic acid (PLLA) suggests adequate hydration (less than equal to 2-24 hours of reconstitution) of the lyophilized particles before injection, but the volume of reconstitution and the duration of hydration time varies. This study established a method to evaluate the distribution of PLLA particles after hydration and found that longer hydration time increased the effective portion (particles less than 60 µm) of PLLA products. Further investigation of the feasibility of reconstitution with sonication revealed that 2-hour hydration of PLLA powders with additional 5-minute-sonication could yield a comparable particle distribution with 48-hour-hydration of PLLA. Moreover, adding lidocaine into the diluent did not alter the distribution of PLLA particles. We proposed a new, feasible and efficient method of preparing PLLA injectable products: 2-hour hydration of the powders, sonication of the bottle or vial containing PLLA products for at least 5 minutes, and finalization with 1-2 mL of lidocaine immediately before injection. J Drugs Dermatol. 2018;17(8):894-898.

Characterization of cavitation-radiated acoustic power using diffraction correction.

A method is developed for compensating absolute pressure measurements made by a calibrated passive cavitation detector (PCD) to estimate the average acoustic power radiated from a region of interest (ROI) defined to encompass all cavitating bubbles. A diffraction correction factor for conversion of PCD-measured pressures to cavitation-radiated acoustic power per unit area or volume is derived as a simple analytic expression, accounting for position- and frequency-dependent PCD sensitivity. This approach can be applied to measurements made by any PCD without precise knowledge of the number, spatial, or temporal distribution of cavitating bubbles. The diffraction correction factor is validated in simulation for a wide range of ROI dimensions and frequencies. The correction factor is also applied to emission measurements obtained during in vitro ultrasound-enhanced sonophoresis experiments, allowing comparison of stable cavitation levels between therapeutic configurations with different source center frequencies. Results incorporating sonication at both 0.41 and 2.0 MHz indicate that increases in skin permeability correlate strongly with the acoustic power of subharmonic emissions radiated per unit skin area.

Methodology on quantification of sonication duration for safe application of MR guided focused ultrasound for liver tumour ablation.

BACKGROUND AND OBJECTIVE: Magnetic Resonance Guided Focused Ultrasound (MRgFUS) for liver tumour ablation is a challenging task due to motion caused by breathing and occlusion due the ribcage between the transducer and the tumour. To overcome these challenges, a novel system for liver tumour ablation during free breathing has been designed. METHODS: The novel TRANS-FUSIMO Treatment System (TTS, EUFP7) interacts with a Magnetic Resonance (MR) scanner and a focused ultrasound transducer to sonicate to a moving target in liver. To meet the requirements of ISO 13485; a quality management system for medical device design, the system needs to be tested for certain process parameters. The duration of sonication and, the delay after the sonication button is activated, are among the parameters that need to be quantified for efficient and safe ablation of tumour tissue. A novel methodology is developed to quantify these process parameters. A computerised scope is programmed in LabVIEW to collect data via hydrophone; where the coordinates of fiber-optic sensor assembly was fed into the TRANS-FUSIMO treatment software via Magnetic Resonance Imaging (MRI) to sonicate to the tip of the sensor, which is synchronised with the clock of the scope, embedded in a degassed water tank via sensor assembly holder. The sonications were executed for 50 W, 100 W, 150 W for 10 s to quantify the actual sonication duration and the delay after the emergency stop by two independent operators for thirty times. The deviation of the system from the predefined specs was calculated. Student's-T test was used to investigate the user dependency. RESULTS: The duration of sonication and the delay after the sonication were quantified successfully with the developed method. TTS can sonicate with a maximum deviation of 0.16 s (Std 0.32) from the planned duration and with a delay of 14 ms (Std 0.14) for the emergency stop. Student's T tests indicate that the results do not depend on operators (p > .05). CONCLUSION: The evidence obtained via this protocol is crucial for translation- of-research into the clinics for safe application of MRgFUS. The developed protocol could be used for system maintenance in compliance with quality systems in clinics for daily quality assurance routines.

Ultrasound extraction optimization of Acanthopanax senticosus polysaccharides and its antioxidant activity.

In this study, effects of several experimental parameters, including ultrasonic time, ratio of water to material, extraction temperature and ultrasonic power on the extraction yield of polysaccharides from Acanthopanax senticosus stem (ASS) were investigated by single factor experiment and an orthogonal test design (L9(3)(4)) was used to optimize the ultrasound extraction conditions. The polysaccharides from Acanthopanax senticosus stem (ASSP) and fruit (ASFP) were further fractionated by stepwise ethanol precipitation and the anti-oxidation activities of those fractions were evaluated by hydroxyl, superoxide anion and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Under the optimal conditions (ultrasonic time 75min, ratio of water to material 50ml/g, extraction temperature 80°C and ultrasonic power 100W), the yield was 10.9mg/g. All fractions of ASP possessed considerable antioxidant activity. The results indicated that the ultrasound extraction was a very useful method for the extraction of ASP and the polysaccharides could be explored as a potential antioxidant agent for use in medicine or functional food.

Characterisation and improvement of a reference cylindrical sonoreactor.

This paper describes theoretical and experimental methods for characterising the performance of a 25 kHz sonochemical reactor (RV-25), which is being developed as a reference facility for studying acoustic cavitation at the National Physical Laboratory (NPL). Field measurements, acquired in different locations inside the sonoreactor, are compared with finite element models at different temperatures, showing that relatively small temperature variations can result in significant changes in the acoustic pressure distribution (and consequent cavitation activity). To improve stability, a deeper insight into the way energy is transferred from the power supply to the acoustic field is presented, leading to criteria - based on modal analysis - to dimension and verify an effective temperature control loop. The simultaneous use of measurements and modelling in this work produced guidelines for the design of multi-frequency cylindrical sonoreactors, also described.

Evaluation of relative importance of ultrasound reactor parameters for the removal of estrogen hormones in water.

The growing interest in sonochemistry as a tool for environmental remediation leads to the need for process optimization. Sonochemistry is a complex process, which depends on physical parameters and also on the process conditions. Physical parameters are interrelated and therefore a systematic approach has to be taken to optimize the process. The effect of physical parameters on the destruction of seven estrogen hormones (17α-estradiol, 17ß-estradiol, estriol, 17α-ethinylestradiol, 17α-dihydroequilin, estrone and equilin) is reported in this study. Artificial neural networks (ANN) was used as a tool to identify the correlations between these process parameters. ANN enabled the establishment of relationship between sonication parameters such as power density, power intensity, ultrasound amplitude, as well as the reactor design parameters. The major significance was attributed to the area-specific power density and the volume-specific power intensity. The results of this work provide a sound basis to design pilot and full-scale ultrasound treatment systems. Process optimization lead to a 5-fold decrease in energy consumption as compared to the commercially available reactors, thereby making the process attractive for field applications.

Ultrasonic dispersion of nanoparticles for environmental, health and safety assessment--issues and recommendations.

Studies designed to investigate the environmental or biological interactions of nanoscale materials frequently rely on the use of ultrasound (sonication) to prepare test suspensions. However, the inconsistent application of ultrasonic treatment across laboratories, and the lack of process standardization can lead to significant variability in suspension characteristics. At present, there is widespread recognition that sonication must be applied judiciously and reported in a consistent manner that is quantifiable and reproducible; current reporting practices generally lack these attributes. The objectives of the present work were to: (i) Survey potential sonication effects that can alter the physicochemical or biological properties of dispersed nanomaterials (within the context of toxicity testing) and discuss methods to mitigate these effects, (ii) propose a method for standardizing the measurement of sonication power, and (iii) offer a set of reporting guidelines to facilitate the reproducibility of studies involving engineered nanoparticle suspensions obtained via sonication.

Calibration of the 1-MHz Sonitron ultrasound system.

Successful drug and gene delivery across cellular membranes can lead to improved therapeutic outcomes. Recent studies have suggested that sonoporation may enhance drug and gene delivery across cellular membranes. The enhancement may be a result of transient permeation of the membrane from cavitation or microstreaming effects of microbubbles exposed to ultrasound. Given limited acoustic pressure calibration and beam profile characterization of the Sonitron ultrasound systems in cellular bioeffects studies previously published, the objective of this work was to calibrate the acoustic output and explore the potential for standing waves in a cell-well plate. In this study, three 1-MHz transducers driven by Sonitron ultrasound systems, which have been used in a number of sonoporation studies, were calibrated. Transducers with 10-mm, 6-mm and 20-mm-diameter apertures (Sonitron 1000 and 2000, Rich-Mar, Inola, OK, USA) were calibrated using polyvinylidene fluoride (PVDF) needle hydrophones. Axial and transverse beam profiles were obtained, and the pressures were measured as a function of Sonitron intensity dial setting and duty cycle. The acoustic intensity was calculated and compared with the Sonitron intensity dial setting for duty cycles from 10-100%. Standing waves caused by reflections from the hydrophone holder were detected for each transducer. This observation may also have implications for in vitro sonoporation studies. Acoustic field characterization is an important first step in understanding the mechanisms of sonoporation and drug delivery across biomembranes.

Toward a reference ultrasonic cavitation vessel: Part 2--investigating the spatial variation and acoustic pressure threshold of inertial cavitation in a 25 kHz ultrasound field.

As part of an ongoing project to establish a reference facility for acoustic cavitation at the National Physical Laboratory (NPL), carefully controlled studies on a 25 kHz, 1.8 kW cylindrical vessel are described. Using a patented high-frequency acoustic emission detection method and a sonar hydrophone, results are presented of the spatial variation of inertial acoustic cavitation with increasing peak-negative pressure. Results show that at low operating levels, inertial acoustic cavitation is restricted to, and is strongly localized on, the vessel axis. At intermediate power settings, inertial acoustic cavitation also occurs close to the vessel walls, and at higher settings, a complex spatial variation is seen that is not apparent in measurements of the 25 kHz driving field alone. At selected vessel locations, a systematic investigation of the inertial cavitation threshold is described. This was carried out by making simultaneous measurements of the peak-negative pressures leading to inertial cavitation and the resultant MHz-frequency emissions, and indicates an inertial cavitation threshold of 101 kPa +/- 14% (estimated expanded uncertainty). However, an intermediate threshold at 84 kPa +/- 14% (estimated expanded uncertainty) is also seen. The results are discussed alongside theoretical predictions and recent experimental findings.