Conventional Ultrasonic Devices Research Articles

Ultrasound-triggered imaging and drug delivery using microbubble-self-aggregate complexes

Co-delivery of microbubbles (MBs) with anticancer drugs is a promising theranostic approach that can enhance both the ultrasound contrast and local extravasation of drugs with the sonoporation effect. The simultaneous administration of MBs and hydrophobic drugs, however, is still challenging due to the limitations in drug loading or undesirable stabilization of MBs. In this research, MB-self-aggregate complexes (MB-SAs) were newly fabricated for the encapsulation of hydrophobic drugs, and their theranostic properties are investigated in vitro and in vivo. Glycol chitosan self-aggregates (GC-SAs) loaded with hydrophobic drugs or dyes were chemically conjugated on the surface MBs. Their conjugation ratio was determined to be 73.9%, and GC-SAs on MBs did not affect the stability of MBs. GC-SA attached MBs (GC@MBs) were successfully visualized with low-intensity insonation and showed enhanced cellular uptake via the sonoporation effect. In vivo biodistribution of GC@MBs was examined with tumor-bearing mice, confirming that their accumulation at the tumor site increased by 1.85 times after ultrasound irradiation. The anticancer drug-loaded GC@MBs also exhibited 10% higher cytotoxicity under ultrasound flash. In conclusion, it was expected that GC@MBs could be used both as an ultrasound contrast agent and a drug carrier even with conventional ultrasonic devices.

Harvest of the right gastroepiploic artery graft using a novel hybrid ultrasonic/bipolar energy device.

The right gastroepiploic artery (RGEA) is a useful in-situ graft, and skeletonization is effective to prevent spasm and achieve good patency. To harvest the skeletonized RGEA easily, ultrasonic scalpel has been widely used, but the tip shape of conventional ultrasonic device was not optimal for this procedure. Recently, a novel hybrid ultrasonic/bipolar energy device (THUNDERBEAT Open Fine Jaw [TOFJ]) has been developed and is widely used in general surgery. The operator holds forceps in left hand and TOFJ in right hand, incises the anterior layer of the omentum, and extends the incision distally along the RGEA. The side branches and satellite veins were sealed and cut. Because the tip of the TOFJ is well-designed to easily grasp and peel off the tissue, there is no need to change instruments throughout the procedure. After the dissection was advanced distally, the proximal side was subsequently dissected. This novel device is useful for harvesting skeletonized RGEA.

A new ultrasonic system in initial periodontal therapy: clinical efficacy and perception of pain

To compare the clinical efficacy and perception of pain during initial periodontal treatment using Vector-system and a conventional ultrasonic system. Thirty-eight patients with mild to moderate periodontitis were debrided using both A-system (Vector-system) and B-system (Suprasson P5 Newtron) in a split mouth design. At baseline, one month after treatment, plaque index (PLI) and bleeding on probing (BOP) were recorded and probing depth(PD) was measured. A verbal analogue scale (VAS) was used to evaluate the perceived pain right after the treatment. At one month evaluation, all areas showed an improvement in clinical parameters. No statistically significant differences in PD and BOP could be observed between areas treated by two different systems, while A-system contributed to greater improvement in PLI than B-system. Patients treated with A-system [(22.5 +/- 7.5) mm] experienced about 60% the amount of pain compared with the conventional ultrasonic device [(37.2 +/- 11.3) mm]. During initial periodontal treatment for the patients with mild to moderate periodontitis, A-system could achieve a comparable clinical efficacy and reduced pain sensations to conventional ultrasonic device.

Ultrasonic radio-frequency spectrum analysis of normal brain tissue

Acoustic tissue properties can be estimated using texture and/or spectral parameter analysis. Spectral analysis is based on the rf-signals whose frequency-content is commonly neglected in conventional B-mode imaging. Attenuation and backscatter values of normal brain tissue were analyzed. Unprocessed rf-data of 20 patients were sampled intraoperatively after craniotomy using a modified conventional ultrasonic device (Hitachi CS 9600) and analyzed off-line by a custom-made software routine. Prior to parameter estimation, influences of the diffraction pattern were compensated by means of a correction function obtained using a tissue-mimicking phantom. Attenuation of white matter showed a linear frequency dependence with a slope of 0.94±0.13 dB x cm-1 x MHz-1. The spectral slope was determined using 10 distinct frequencies between 2.5MHz and 5.75MHz. Backscattering properties were analyzed by determining the power spectral density (PSD) and a relative backscatter coefficient (rel BSC) against the values derived from the tissue-mimicking phantom. PSD and rel BSC values were frequency-dependent, with highest PSD values at the probe's center frequency (-75.69±8.26 dB V2 Hz-1). The corresponding rel BSC value at 5MHz was determined as 15.39±8.26 dB. Finally, backscatter coefficients (BSC) of brain tissue were computed using the known BSC of the phantom. The data provided in this study are meant to serve as a base for intended future characterization of brain tissue that potentially allows intraoperative differentiation between normal and pathological areas and therefore provides the surgeon with additional information for defining the extent of resection in brain more precisely.

Subjective intensity of pain during ultrasonic supragingival calculus removal

To assess subjective intensities of pain during supragingival calculus removal employing ultrasonic scaler tips of two different shapes. Twenty patients were treated using a piezoelectric ultrasonic device (Sirosonic L) and two different scaler tips representing a conventional (Instrument No. 3) and a slim-line style (Perio Pro Line Instrument SI-11) in a split-mouth design. Pain was recorded during calculus removal at intervals of 0.5 s employing an inter-modal intensity comparison. Additionally, a visual analogue scale was used for evaluation directly after the treatment procedure. Treatment time was recorded to assess the efficiency of calculus removal. Pain assessment during treatment showed that the slim-line scaler tip (median pain score: 1.4 [U], maximum: 3.5 [U], minimum: 0 [U]) caused less pain than the conventional device (median pain score: 7.8 [U], maximum: 14.7 [U], minimum: 0 [U]) (p<0.05). These results could be confirmed by the visual analogue scale. Treatment with the slim-line tip took significantly longer than treatment with the conventional tip (p<0.05). Using slim-line-styled ultrasonic scaler tips for supragingival calculus removal, painful sensations can be reduced compared with conventional ultrasonic devices. Thus, it might be possible to increase the patient's compliance during dental treatment with oscillating instruments.

Statistical modelling of ultrasonic sensors in process industries—new prospects for conventional devices

The acoustic impedance of different fluids was indirectly measured by analysing the reverberation of a pulsed ultrasonic transducer showing a design as applied in contemporary process instrumentation. The set of observed fluids comprises air, methanol, ethanol, toluene, water and glycerine, which are substances of extremely different acoustic properties. The fluid impedance was precisely gauged using statistical linear models. The model complexity as well as the required calibration effort was minimized including a priori knowledge about the electrical characteristic of the transducer near resonance. The predictive power of different linear model estimates in terms of ordinary least squares, principal component regression and partial least squares was compared. A compensation method was proposed correcting the impact of temperature variation on analysed data. Additionally measured transit time permits the precise estimation of the density of arbitrary homogeneous fluids of varying temperature using traditional transducer designs. Thereby the functional range of conventional ultrasonic devices in process industries can be extended without the need for constructive modifications.

Ultrasonic Radio-Frequency Spectrum Analysis of Normal Brain Tissue

Acoustic tissue properties can be estimated using texture and/or spectral parameter analysis. Spectral analysis is based on the rf-signals whose frequency-content is commonly neglected in conventional B-mode imaging. Attenuation and backscatter values of normal brain tissue were analyzed. Unprocessed rf-data of 20 patients were sampled intraoperatively after craniotomy using a modified conventional ultrasonic device (Hitachi CS 9600) and analyzed off-line by a custom-made software routine. Before parameter estimation, influences of the diffraction pattern were compensated by means of a correction function obtained using a tissue-mimicking phantom. Attenuation of white matter showed a linear frequency dependence with a slope of 0.94 ± 0.13 dB cm −1 MHz −1. The spectral slope was determined using 10 distinct frequencies between 2.5 and 5.75 MHz. Backscattering properties were analyzed by determining the power spectral density (PSD) and a relative backscatter coefficient (rel BSC) against the values derived from the tissue-mimicking phantom. PSD and rel BSC values were frequency-dependent, with highest PSD values at the probe’s center frequency (−75.69 ± 8.26 dB V 2 Hz −1). The corresponding rel BSC value at 5 MHz was determined as 15.39 ± 8.26 dB. Finally, backscatter coefficients (BSC) of brain tissue were computed using the known BSC of the phantom. The data provided in this study are meant to serve as a base for intended future characterization of brain tissue that potentially allows intraoperative differentiation between normal and pathologic areas and therefore provides the surgeon with additional information for defining the extent of resection in brain more precisely. (E-mail: martin.strowitzki@uniklinik-saarland.de)

A new ultrasonic device in maintenance therapy: perception of pain and clinical efficacy

A recently introduced piezo-driven ultrasonic device (Vector) generates longitudinal oscillations. As a result, the instrument tip moves parallel to the tooth surface. By avoiding vertical oscillations, maintenance treatment with the Vector device should be less painful than treatment with conventional systems. We investigated whether patients perceive treatment with the Vector device as less painful than with a conventional ultrasonic device, and whether the clinical efficacy of the Vector device is comparable with that of the conventional ultrasonic device in maintenance patients. Thirty-eight maintenance patients with moderate to advanced periodontal disease took part in this prospective, randomized controlled clinical study. Each patients had to have at least two teeth with probing depths of >4 mm. They were treated either with Dentsply (n=22) at a reduced power setting or with the Vector device (n=16). The observation period was 6 months. Probing pocket depth, attachment level, and bleeding upon probing were assessed at six sites on each treated tooth by a blinded investigator Patient were asked to report perceived pain during instrumentation with a visual analog scale immediately after treatment, in the evening of the treatment day, and in the evenings 1 and 2 days after treatment. Bleeding on probing, probing depth, and attachment level improved in both instrumentation groups from baseline to month 6; however, there was no difference between the two instrumentation modalities. The patients perceived treatment with neither instrument as unpleasant, and their perception of pain intensity both during instrumentation and on the following days did not differ. In maintenance therapy, clinical efficacy of the vector device is comparable with that of conventional ultrasonic device. It makes no difference whether the ultrasonic device at a reduced power setting or the Vector device is used, since patients perceive both instruments as causing very little pain.