Use of three-dimensional MRI-angiography in preoperative evaluation and postoperative management of hemangiomas of head and neck region.

Hemangiomas (proliferating endothelial tumors) are the most common benign tumors of infancy. Most often hemangiomas are self-regressing lesions without any treatment. Approximately 10% of hemangiomas cause complications such as major ulceration/destruction, distortion of involved tissues, and obstruction of a vital structure. When the situation becomes complicated, there are different treatment alternatives, ranging from systemic or local corticosteroid use to surgery. Sclerotherapy using intralesional polidocanol (Aethoxysklerol) injection may be used before surgery to decrease blood loss or when a vital structure of the face is in danger because of sudden increase in size of a surrounding hemangioma. Before any kind of treatment for both hemangiomas and vascular malformations, preoperative diagnosis and anatomic position of the lesion must be documented thoroughly. With the help of magnetic resonance imaging, tridimensional vascular pattern of such lesions can be shown successfully. We used three-dimensional contrast-enhanced time-resolved magnetic resonance angiography to detect the changes of lesions for 2 children who have large hemangiomas on their faces, before and after sclerotherapy with polidocanol injection. The findings of three-dimensional magnetic resonance imaging studies help to better assess the success rate of treatment not only for us as the physicians but also for the parents of these children who cannot understand anything with standard two-dimensional radiologic imaging.

Pore-scale studies of spontaneous imbibition into oil-saturated porous media.

Spontaneous imbibition phenomenon was modeled using the lattice Boltzmann method (LBM). The model was validated using silicon-etched micromodel and sandpack visualization experiments. The strongly water-wet model saturated with oil (kerosene or mineral oil) was exposed to distilled water in order for a capillary interaction to take place under static conditions. These experiments mimic the transfer between rock matrix and fracture during any wetting phase flow in fractures while the matrix contains a nonwetting phase as encountered in oil, gas, and geothermal reservoirs as well as during the application of subsurface CO2 sequestration or waste disposal reservoirs. Despite the vast amount of research work on this common process, pore-scale investigations and modeling are limited especially at small time scales. The results showed that the LBM captures the physics of the process at pore scale for low viscosity values of nonwetting phase for any type of (cocurrent or countercurrent imbibition) interaction.

Lattice-Boltzmann simulation of solvent diffusion into oil-saturated porous media.

We simulated the diffusion process into oil-saturated porous media using the modified diffusion-limited aggregation and the lattice Boltzmann method algorithms. The results were matched to visual experiments for cocurrent (two sides of the model open to flow) and countercurrent (only one side of the model open to flow) diffusion for horizontally and vertically positioned samples. The model saturated with oil was exposed to pentane in order for a miscible interaction to take place. These experiments mimic the transfer between the rock matrix and fracture during gas or liquid solvent injection for enhanced oil recovery, underground waste disposal, groundwater contamination, and CO2 sequestration in naturally fractured reservoirs. Finger development at the early stages of the process was controlled by oil viscosity and the interaction type dictated by the boundary conditions. The convective transport driven by the buoyancy that was experimentally observed on vertically oriented samples and transfer driven by diffusion on the horizontal ones were captured in the LBM simulation of the process.