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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 94 out of 330
| Title |
Driving delivery vehicles with ultrasound. |
| Author |
Ferrara KW. |
| Journal |
Adv Drug Deliv Rev |
| Volume |
|
| Year |
2008 |
| Abstract |
Therapeutic applications of ultrasound have been considered for over 40 years, with the mild hyperthermia and associated increases in perfusion produced by ultrasound harnessed in many of the earliest treatments. More recently, new mechanisms for ultrasound-based or ultrasound-enhanced therapies have been described, and there is now great momentum and enthusiasm for the clinical translation of these techniques. This dedicated issue of Advanced Drug Delivery Reviews, entitled "Ultrasound for Drug and Gene Delivery," addresses the mechanisms by which ultrasound can enhance local drug and gene delivery and the applications that have been demonstrated at this time. In this commentary, the identified mechanisms, delivery vehicles, applications and current bottlenecks for translation of these techniques are summarized. |
| Title |
Drug delivery by phonophoresis. |
| Author |
Tyle P, Agarwala P. |
| Journal |
Pharm Res |
| Volume |
|
| Year |
1989 |
| Abstract |
Phonophoresis is defined as the migration of drug molecules, contained in a contact agent, through the skin under the influence of ultrasound. Several drugs have been introduced into the body by this technique. The design of a phonophoretic drug delivery system is in developmental stages in various research laboratories. Parameters affecting the delivery of drugs by this technique and devices available for drug delivery purposes are discussed in this review. |
| Title |
Dual-high-frequency ultrasound excitation on microbubble destruction volume. |
| Author |
Shen CC, Su SY, Cheng CH, Yeh CK. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
2010 |
| Abstract |
No Abstract Available. |
| Title |
Dual-mode ultrasound phased arrays for image-guided surgery. |
| Author |
Ebbini ES, Yao H, Shrestha A. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
2006 |
| Abstract |
A 64-element, 1 MHz prototype dual-mode array (DMUA) with therapeutic and imaging capabilities is described. Simulation and experimental results for the characterization of the therapeutic operating field (ThxOF) and imaging field-of-view (IxFOV) for a DMUA are given. In addition, some of the special considerations for imaging with DMUAs are given and illustrated experimentally using wire-target arrays and commercial, quality-assurance phantoms. These results demonstrate what is potentially the most powerful advantage of the use of DMUAs in image-guided surgery; namely, inherent registration between the imaging and therapeutic coordinate systems. We also present imaging results before and after discrete and volumetric HIFU-induced lesions in freshly-excised tissues. DMUA images consistently show changes in echogenicity after lesion formation with shape and extent reflecting the actual shape of the lesion. While changes in echogenicity cannot be used as an indicator of irreversible HIFU-induced tissue damage, they provide important feedback on the location and extent of the expected lesion. Thus, together with the self-registration property of DMUAs, lesion images can be expected to provide immediate and spatially-accurate feedback on the tissue response to the therapeutic HIFU beams. Based on the results provided here, the imaging capabilities of DMUAs can add unique features to other forms of image guidance, e.g. MRI, CT and diagnostic ultrasound. |
| Title |
Duplex Doppler scanning in the pelvis and abdomen. |
| Author |
Taylor KJ, Burns PN. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1985 |
| Abstract |
New Doppler applications of Doppler ultrasound are becoming apparent in the abdomen and pelvis. Interpretation of the Doppler signals may be qualitative, semiqualitative or quantitative. Normal time-velocity spectra in major vessels of the abdomen and pelvis are described. In the diagnosis in pathology, Doppler can be used to document the presence and direction of flow in the portal venous system. In can aid in the identification of an abnormal structure. It provides much of the perfusion data required before and subsequent to liver transplantation. In normotopic renal vessels, it can exclude thrombosis and stenoses in many patients. In renal transplants, it is invaluable as a rapid means to assess patency, renal artery stenosis and vascular rejection, thereby extending the role of conventional imaging. Early studies in the pelvis have demonstrated changes in the ovarian signals associated with ovulation. Doppler can be used to assess bowel viability, impotence due to vascular insufficiency and to exclude testicular torsion. Finally, blood flow in malignant tumors has been demonstrated to give rise to Doppler signals with characteristic qualities, and this technique awaits thorough investigation in the abdomen. |
| Title |
Duty cycle and pulse length dependence of the acoustic cavitation threshold at megahertz frequencies. |
| Author |
Calabrese AM, Roy RA, Crum LA. |
| Journal |
Proc Thirteenth Int Symp Nonlinear Acoust |
| Volume |
|
| Year |
1993 |
| Abstract |
It has been recently demonstrated that acoustic cavitation can be produced in aqueous liquids with clinical ultrasound instruments. These devices can be used in an imaging mode, which utilizes a short, timing pulse, or in a Doppler mode, which utilizes a somewhat longer pulse containing frequency information; a variety of pulse repetition frequencies are used to optimize the images. We have developed an extremely sensitive technique for detecting microcavitation which is particularly applicable to that generated by microsecond-length pulses. Using this technique we have investigated the dependence of the threshold for cavitation inception on the duty cycle, the pulse length and the acoustic frequency for a variation of host liquid conditions. These results will be related to the potential for cavitation inception in clinical instruments, and to the specific phenomenon of cavitation in general. |
| Title |
Duty cycle dependance of ultrasound enhanced thrombolysis in a human clot model. |
| Author |
Meunier JM, Holland CK, Lindsell CJ, Shaw GJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2007 |
| Abstract |
Combined ultrasound and tissue plasminogen activator (rt-PA) therapy, or ultrasound enhanced thrombolysis (UET), has been shown to improve recanalization in patients with acute ischemic stroke. We measured the effect of ultrasound duty cycle on the lytic efficacy of 120 kHz UET in an in vitro human clot model. The hypothesis was that an increase in duty cycle increases rt-PA lytic efficacy. Human whole blood clots were exposed to 120-kHz ultrasound and rt-PA for 30 min in human plasma. The duty cycle ranged from 0% to 80%, where 0% represents sham exposure. Clot lytic rate was measured by recording the clot width over time. The clot width after 30 min exposure to rt-PA and ultrasound decreases with increasing duty cycle. The initial lytic rate increased linearly with duty cycle. |
| Title |
Duty cycle dependence of ultrasound enhanced thrombolysis in a human clot model. |
| Author |
Meunier JM, Holland CK, Lindsell CJ, Shaw GJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2007 |
| Abstract |
Combined ultrasound and tissue plasminogen activator (rt-PA) therapy, or ultrasound enhanced thrombolysis (UET), has been shown to improve recanalization in patients with acute ischemic stroke. We measured the effect of ultrasound duty cycle on the lytic efficacy of 120 kHz UET in an in vitro human clot model. The hypothesis was that an increase in duty cycle increases rt-PA lytic efficacy. Human whole blood clots were exposed to 120-kHz ultrasound and rt-PA for 30 min in human plasma. The duty cycle ranged from 0% to 80%, where 0% represents sham exposure. Clot lytic rate was measured by recording the clot width over time. The clot width after 30 min exposure to rt-PA and ultrasound decreases with increasing duty cycle. The initial lytic rate increased linearly with duty cycle. |
| Title |
Dynamic adsorption properties of n-alkyl glucopyranosides determine their ability to inhibit cytolysis mediated by acoustic cavitation |
| Author |
Sostaric JZ, Miyoshi N, Cheng JY, Riesz P. |
| Journal |
J Phys Chem |
| Volume |
|
| Year |
2008 |
| Abstract |
Suspensions of human leukemia (HL-60) cells readily undergo cytolysis when exposed to ultrasound above the acoustic cavitation threshold. However, n-alkyl glucopyranosides (hexyl, heptyl, and octyl) completely inhibit ultrasound-induced (1057 kHz) cytolysis (Sostaric, et al. Free Radical Biol. Med. 2005, 39, 1539−1548). The efficacy of protection from ultrasound-induced cytolysis was determined by the n-alkyl chain length of the glucopyranosides, indicating that protection efficacy depended on adsorption of n-alkyl glucopyranosides to the gas/solution interface of cavitation bubbles and/or the lipid membrane of cells. The current study tests the hypothesis that “sonoprotection” (i.e., protection of cells from ultrasound-induced cytolysis) in vitro depends on the adsorption of glucopyranosides at the gas/solution interface of cavitation bubbles. To test this hypothesis, the effect of ultrasound frequency (from 42 kHz to 1 MHz) on the ability of a homologous series of n-alkyl glucopyranosides to protect cells from ultrasound-induced cytolysis was investigated. It is expected that ultrasound frequency will affect sonoprotection ability since the nature of the cavitation bubble field will change. This will affect the relative importance of the possible mechanisms for ultrasound-induced cytolysis. Additionally, ultrasound frequency will affect the lifetime and rate of change of the surface area of cavitation bubbles, hence the dynamically controlled adsorption of glucopyranosides to their surface. The data support the hypothesis that sonoprotection efficiency depends on the ability of glucopyranosides to adsorb at the gas/solution interface of cavitation bubbles. |
| Title |
Dynamic behavior of bubbles during extracorporeal shock-wave lithotripsy. |
| Author |
Kodama T,Takayama K. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1998 |
| Abstract |
The interaction of air bubbles attached to gelatin surfaces, extirpated livers or abdominal aortas of rats with underwater shock waves was investigated to help clarify the tissue-damage mechanism associated with cavitation bubbles induced during extracorporeal shock-wave lithotripsy. The overpressure of the shock wave was 10.2 +/- 0.5 MPa. The initial bubble radii varied from 0.12 to 3.06 mm. The subsequent collapse of the bubbles was recorded by a high-speed camera. The liver-cell damage was histochemically evaluated. The bubble attached to gelatin or rat's liver surface migrates away from the surface with an oscillatory growth/collapse behavior after the shock-wave interaction. The penetration depth of the liquid jet into the gelatin and the radius of the subsequent damage pit on the surface depend on the initial bubble radius. The elongation and split of the nuclei in the liver parenchymal cells in the direction of the liquid jet and the increase in the cell density within the circumference of the injured region are revealed histologically. |
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