The current status of the use of nanoparticles for photothermal treatments is reviewed in detail. The different families of heating nanoparticles are described paying special attention to the physical mechanisms at the root of the light-to-heat conversion processes. The heating efficiencies and spectral working ranges are listed and compared. The most important results obtained in both in vivo and in vitro nanoparticle assisted photothermal treatments are summarized. The advantages and disadvantages of the different heating nanoparticles are discussed.

Nanoparticles for photothermal therapies.

https://pure.tue.nl/ws/files/1819452/585551.pdf

A new method to determine trabecular bone elastic properties and loading using micromechanical finite-element models

The invention provides improved devices, methods, and systems for shrinking of collagenated tissues, particularly for treating urinary incontinence in a noninvasive manner by directing energy to a patient's own support tissues. This energy heats fascia and other collagenated support tissues, causing them to contract. The energy can be applied intermittently, often between a pair of large plate electrodes having cooled flat electrode surfaces, the electrodes optionally being supported by a clamp structure. Such cooled plate electrodes are capable of directing electrical energy through an intermediate tissue and into fascia while the cooled electrode surface prevents injury to the intermediate tissue, particularly where the electrode surfaces are cooled before, during, and after an intermittent heating cycle. Ideally, the plate electrode comprises an electrode array including discrete electrode surface segments so that the current flux can be varied to selectively target the fascia. Alternatively, chilled “liquid electrodes” may direct current through a selected portion of the bladder (or other body cavity) while also cooling the bladder wall, an insulating gas can prevent heating of an alternative bladder portion and the adjacent tissues, and/or ultrasound transducers direct energy through an intermediate tissue and into fascia with little or no injury to the intermediate tissue. Cooled electrodes may be used to chill an intermediate engaged tissue so as to cause the maximum temperature difference between the target tissue and the intermediate tissue prior to initiating RF heating. This allows the dimensions of tissue reaching the treatment temperature to be controlled and/or minimized, the dimensions of protected intermediate tissue to be maximized, and the like.

Noninvasive devices, methods, and systems for shrinking of tissues

— —Pathologic analysis of the biologic effects and mechanisms of laser–tissue interactions requires correlation of the irradiation parameters with the biologic status and response of the target tissues over time. The photobiologic mechanisms of laser-induced tissue injury can be separated into three categories, photochemical, photothermal and photomechanical. Anatomic pathologic analysis of laser-induced lesions reveals alterations that represent either specific markers of the photobiologic mechanism or non-specific reactions to tissue injury. Repair, regeneration and wound healing of laser induced lesions appear to be non-specific responses to the type of tissue damage rather than the photobiologic mechanism producing the lesion.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097.1991.tb09897.x

Pathologic analysis of photothermal and photomechanical effects of laser-tissue interactions.

Devices, systems, and method for treating urinary incontinence generally rely on energy delivered to a patient's own pelvic support tissue to selectively contract or shrink at least a portion of that pelvic support tissue so as to reposition the bladder. The energy will preferably be applied to the endopelvic fascia and/or an arcus tendineus fascia pelvis. The invention provides a variety of devices and methods for applying gentle resistive heating of these and other tissues to cause them to contract without imposing significant injury on the surrounding tissue structures. Alternatively, heat-applying probes are configured to heat tissue structures which comprise or support a patient's urethra. By applying sufficient energy over a predetermined time, the tissue can be raised to a temperature which results in contraction without significant necrosis or other tissue damage. By selectively contracting the support tissues, the bladder neck, sphincter, and other components of the urinary tract responsible for the control of urinary flow can be reconfigured or supported in a manner which reduces urinary leakage.

Devices, methods, and systems for shrinking tissues

Iterative Methods for Large Linear Systems

The burn process resulting from the application of a hot, cylindrical source to the skin surface was modeled using the finite element technique. A rotationally symmetric 125-element mesh was defined within the tissue beneath and outlying to an applied heating disk. The disk temperature and duration of contact were varied, respectively, between 50 and 100 degrees C for up to 30 s. Natural convection with ambient air was assumed for areas of skin surface not in direct contact with the disk. The simulated thermal history was used in a damage integral model to calculate the extent and severity of injury in the radial and axial dimensions.

A Finite Element Model of Burn Injury in Blood-Perfused Skin

The thermal properties of adipose and ceramic atherosclerotic plaque deposits and normal arterial vessel wall were measured in the temperature range of 25-95 degrees C. In general, the data indicate that fatty plaques exhibit the lowest thermal conductivity and thermal diffusivity of the three types, whereas calcified plaques seem to have the highest values. By using a video scanning thermograph, temperature rise was recorded in normal vessel wall and plaque during ablation of tissue. Theoretical analysis suggested that realistic modeling of laser angioplasty should account for scattering of light, water content, and ablation. This paper is a preliminary report of these results.

Effect of laser radiation on tissue during laser angioplasty.

The role of optical properties in the distribution of laser light and the resulting thermodynamical processes in biological tissue are studied from a theoretical perspective. Light distribution is modeled by a discrete ordinate method, and heat transfer and ablation are modeled by an immobilized finite-element method. The effect of parametric variation of absorption, scattering, and scattering anisotropicity on the dynamics of the ablation process is examined. The manifestation of temperature higher than the ablation threshold temperature in the subsurface tissue is observed and discussed. Results indicate significant differences in the ablation behavior, which may have important clinical implications. >

Linda J. Hayes

Papers

Iterative Methods for Large Linear Systems

A Finite Element Model of Burn Injury in Blood-Perfused Skin

Effect of laser radiation on tissue during laser angioplasty.

A theoretical study of the effect of optical properties in laser ablation of tissue

Analysis of tissue injury by burning: comparison of in situ and skin flap models