Focused US system for MR imaging-guided tumor ablation.

Abstract

MR imaging provides target definition and control for thermal therapy in regions of variable perfusion or in tissues that are not well characterized.

In vitro and in vivo transfection of plasmid DNA in the Dunning prostate tumor R3327-AT1 is enhanced by focused ultrasound

“…Focused sinusoidal continuous-wave ultrasound is easier to control than lithotripter waves 23,26,34 and especially in a potential clinical setting it can be noninvasively guided by magnetic resonance imaging (MRI). 30,31 The reason for this potential ultrasound focus guidance by MRI is that in the focal area of the ultrasound beam small physiological changes including temperature changes can be induced which can be localized by MRI measurements.…”

“…26 Nevertheless, focused ultrasound-induced gene transfection could be favorably combined with the thermal effects of focused ultrasound occurring at increasing intensities, especially in cancer therapy. MRI-guided noninvasive focused ultrasound therapy 30,31 in combination with ultrasound induced transfer of drug-activating genes like the cytosine deaminase and the herpes simplex thymidine kinase gene 3 could result in an interesting locoregional tumor treatment option.…”

“…It can noninvasively direct energy to a defined area superficially or deeply situated in the body. 31 Ultrasound can influence the physiological tissue conditions leading to cell alterations that result in enhanced permeability of the cell membrane for large molecules without causing cell death. [15][16][17] Restrictions occur by wave reflection and significant temperature increase at bone or air interfaces.…”

“…[15][16][17] Restrictions occur by wave reflection and significant temperature increase at bone or air interfaces. [27][28][29][30][31] There are two possible ways of DNA administration before sonication. First, the direct injection into solid organs, which may include liver, 38 muscle, 10 skin, 12 as well as potentially prostate and breast.…”

“…29 Other advantages of focused sinusoidal ultrasound compared with alternative ultrasound applications are that the focus can be noninvasively positioned at variable depth and its size can be modified. 30,31 In principle, all locations in the human body that can be accessed by percutaneous or endoluminal clinical diagnostic ultrasound devices are possible target sites. If the target volume exeeds the ultrasound focus, it can be sonicated by multiple exposures.…”