Investigation of Biotransport in a Tumor With Uncertain Material Properties Using a Nonintrusive Spectral Uncertainty Quantification Method.

In this study, statistical models are developed for modeling uncertain heterogeneous permeability and porosity in tumors, and the resulting uncertainties in pressure and velocity fields during an intratumoral injection are quantified using a nonintrusive spectral uncertainty quantification (UQ) method. Specifically, the uncertain permeability is modeled as a log-Gaussian random field, represented using a truncated Karhunen-Lòeve (KL) expansion, and the uncertain porosity is modeled as a log-normal random variable. The efficacy of the developed statistical models is validated by simulating the concentration fields with permeability and porosity of different uncertainty levels. The irregularity in the concentration field bears reasonable visual agreement with that in MicroCT images from experiments. The pressure and velocity fields are represented using polynomial chaos (PC) expansions to enable efficient computation of their statistical properties. The coefficients in the PC expansion are computed using a nonintrusive spectral projection method with the Smolyak sparse quadrature. The developed UQ approach is then used to quantify the uncertainties in the random pressure and velocity fields. A global sensitivity analysis is also performed to assess the contribution of individual KL modes of the log-permeability field to the total variance of the pressure field. It is demonstrated that the developed UQ approach can effectively quantify the flow uncertainties induced by uncertain material properties of the tumor.

Two cases of intraoperative diagnosed Amyand hernia: Case report and literature review.

INTRODUCTION: Amyand hernia is the presence of an incarcerated vermiform appendix (either inflamed or not) within the hernia sac. This type of hernia is very rare with an incidence reported to be 0.5 to 1 % and even rarer in adults. CASES PRESENTATION: We present here two cases of male patients found the have an Amyand Hernia diagnosed incidentally intraoperatively, and managed with appendectomy and mesh herniorrhaphy. CLINICAL DISCUSSION: For the management of this type of hernia, in general, the surgeon should perform an appendectomy with the repair to prevent future herniation or appendicitis, but some opinions differ, and state that when there are no signs of inflammation, it is not required to perform a preventative appendectomy. CONCLUSION: The decision on how to manage depends on multiple factors including inflammation of the appendix, the possibility of abdominal sepsis, and the patient comorbidities. The status of the appendix determines whether to undergo hernia repair with or without mesh.

An in-vivo experimental study of temperature elevations in animal tissue during magnetic nanoparticle hyperthermia.

In magnetic nanoparticle hyperthermia in cancer treatment, the local blood perfusion rate and the amount of nanofluid delivered to the target region are important factors determining the temperature distribution in tissue. In this study, we evaluate the effects of these factors on the heating pattern and temperature elevations in the muscle tissue of rat hind limbs induced by intramuscular injections of magnetic nanoparticles during in vivo experiments. Temperature distribution in the vicinity of the injection site is measured inside the rat limb after the nanoparticle hyperthermia. The measured temperature elevations at the injection site are 3.5 degrees +/- 1.8 degrees C and 6.02 degrees +/- 0.8 degrees C above the measured body temperature, when the injection amount is 0.1 cc and 0.2 cc, respectively. The full width of half maximum (FWHM) of the temperature elevation, an index of heat transfer in the radial direction from the injection site is found to be approximately 31 mm for both injection amounts. The temperature measurements, together with the measured blood perfusion rate, ambient air temperature, and limb geometry, are used as inputs into an inverse heat transfer analysis for evaluation of the specific absorption rate (SAR) by the nanoparticles. It has been shown that the nanoparticles are more concentrated in the vicinity of the injection site when the injection amount is bigger. The current in vivo experimental studies have demonstrated the feasibility of elevating the tissue temperature above 43 degrees C under the experimental protocol and equipment used in this study.

Multi-scale study of nanoparticle transport and deposition in tissues during an injection process.

In magnetic nanoparticle hyperthermia for cancer treatment, controlling the nanoparticle distribution delivered in tumors is vital for achieving an optimum distribution of temperature elevations that enables a maximum damage of the tumorous cells while minimizing the heating in the surrounding healthy tissues. A multi-scale model is developed in this study to investigate the spatial distribution of nanoparticles in tissues after nanofluid injection into the extracellular space of tissues. The theoretical study consists of a particle trajectory tracking model that considers particle-surface interactions and a macroscale model for the transport of nanoparticles in the carrier solution in a porous structure. Simulations are performed to examine the effects of a variety of injection parameters and particle properties on the particle distribution in tissues. The results show that particle deposition on the cellular structure is the dominant mechanism that leads to a non-uniform particle distribution. The particle penetration depth is sensitive to the injection rate and surface properties of the particles, but relatively insensitive to the injected volume and concentration of the nanofluid.

Temperature distribution during ICG-dye-enhanced laser photocoagulation of feeder vessels in treatment of AMD-related choroidal neovascularization.

Laser photocoagulation of the feeder vessels of age-related macula degeneration-related choroidal neovascularization (CNV) membranes is a compelling treatment modality, one important reason being that the treatment site is removed from the fovea in cases of sub- or juxtafoveal CNV. To enhance the energy absorption in a target feeder vessel, an indocyanine green dye bolus is injected intravenously, and the 805 nm wavelength diode laser beam is applied when the dye bolus transits the feeder vessel; this tends to reduce concomitant damage to adjacent tissue. A 3D theoretical simulation, using the Pennes bioheat equation, was performed to study the temperature distribution in the choroidal feeder vessel and its vicinity during laser photocoagulation. The results indicate that temperature elevation in the target feeder vessel increases by 20% in dye-enhanced photocoagulation, compared to just photocoagulation alone. The dye bolus not only increases the laser energy absorption in the feeder vessel but also shifts the epicenter of maximum temperature away from the sensitive sensory retina and retinal pigment epithelial layers and toward the feeder vessel. Two dominant factors in temperature elevation of the feeder vessel are location of the feeder vessel and blood flow velocity through it. Feeder vessel temperature elevation becomes smaller as distance between it and the choriocapillaris layer increases. The cooling effect of blood flow through the feeder vessel can reduce the temperature elevation by up to 21% of the maximum that could be produced. Calculations were also performed to examine the effect of the size of the laser spot. To achieve the same temperature elevation in the feeder vessel when the laser spot diameter is doubled, the laser power level has to be increased by only 60%. In addition, our results have suggested that more studies are needed to measure the constants in the Arrhenius integral for assessing thermal damage in various tissues.