Architectural configuration and microstructural properties of the sacral plexus: A diffusion tensor MRI and fiber tractography study

The ability to investigate microstructural properties of the central nervous system with diffusion tensor imaging (DTI) has been shown in many studies. More recently, DTI is being applied outside the brain showing promising results, for instance, for investigating muscle tissue. In this work, we demonstrate the feasibility of diffusion tensor imaging (DTI) and fiber tractography to study the nerves of the sacral plexus in humans in vivo and to assess the architectural configuration and microstructural properties of these peripheral nerves. For this research goal we optimized the acquisition parameters of a DTI sequence and acquired data from 10 healthy adults and one 12-year patient having spina bifida and neurogenic bladder dysfunction. For the healthy volunteers, we estimated the fractional anisotropy (FA) and mean (MD), axial (AD), and radial diffusivities (RD) of the sacral plexus nerves which may serve as a baseline for future studies. We demonstrated that tractography of the sacral plexus on a 3 Tesla MR scanner is feasible, giving 3D insight in the general anatomy and organization of the nerves L4 to S3. In addition, branches to the pudendal nerve were also found in 4 volunteers. There were no significant differences in any of the estimated diffusion measures between the right and left sided nerves or between the nerves L4 to S3 on an intra-subject basis. Furthermore, clinical feasibility of DTI and tractography in a child having spina bifida and neurogenic bladder dysfunction is demonstrated. The architectural configuration of the child's sacral plexus was comparable with the healthy volunteers and no significant disrupted nerve fibers were observed. However, there are strong indications that abnormal diffusion characteristics are present at the level of the neural tube defect due to incomplete segments of the nerves that are close to the vertebrae. These findings are encouraging for using DTI as a means to investigate changes in microstructural properties of the nerves of the sacral plexus. Moreover, this new methodology may provide a new avenue to a better analysis and diagnosis of neurogenic bladder dysfunction

Scanning electron microscopic assessment of coating irregularities and their precursors in unexpanded durable polymer-based drug-eluting stents

Objectives: To assess and quantify coating irregularities on unexpanded and expanded durable polymer-based drug-eluting stents (DES) to gain insights into the origin of coating irregularities. Background: Previous scanning electron microscopy (SEM) studies in various expanded DES revealed differences in frequency and size of coating irregularities between DES types and specific distribution patterns, however, the origin of these irregularities is unclear. Methods: We assessed at bench side a total of 1,200 SEM images obtained in 30 DES samples (15 expanded and 15 unexpanded) of Cypher Select Plus, Taxus Liberté, Endeavor, Xience V, and resolute. Results: For most coating irregularities seen on expanded DES (72%; 23/32), a matching irregularity (n = 18/23) and/or its precursor (n = 11/23) was observed in unexpanded DES. Unexpanded Cypher select showed (small) crater lesions and cracks together with precursors of “peeling.” On unexpanded Taxus Liberté, thinning of polymer, small bare metal areas, wrinkles, and one precursor type were found. Unexpanded endeavor showed cracks, small bare metal areas, crater lesions, and precursors of the latter. Unexpanded Xience V and resolute mainly revealed crater lesions and their precursors. On unexpanded versus expanded DES, there was no difference in measured frequency of coating irregularities and precursors (P = ns) with the exception of more bare metal areas on expanded Taxus Liberte (P = 0.01). Conclusions: Most coating irregularities, or the potential to develop them, are inherent to the unexpanded DES. Important determinants of the formation of coating irregularities may be the stent geometry and the physical properties of the coating, while stent-balloon interaction plays no major role

Initial experiences in the photoacoustic detection of melanoma metastases in resected lymph nodes

Accurate lymph node analysis is essential to determine the prognosis and treatment of patients suffering from melanoma. The initial results of a tomographic photoacoustic modality to detect melanoma metastases in resected lymph nodes are presented based on phantom models and a human lymph node. The results show melanoma metastases detection is feasible and the setup is capable of distinguishing absorbing structures down to 1 mm. In addition, the use of longer laser wavelengths could result in an image containing a higher contrast ratio. Future research shall be focused on using the melanin characteristics to improve contrast and detection possibilities

Pràctiques de Micropaleontologia I

Cuaderno de prácticas de Micropaleontología que abarca las siguientes prácticas: Webs de interés en Micropaleontología, recogida de muestras en campo, levigados, frotis, lámina delgada y observación de muestras: lupa binocular y microscopio.Secretariat de Promoció del Valencià, Universitat d'Alacant; Conselleria d'Educació