Logarithm odds maps for shape representation

The concept of the Logarithm of the Odds (LogOdds) is frequently used in areas such as artificial neural networks, economics, and biology. Here, we utilize LogOdds for a shape representation that demonstrates desirable properties for medical imaging. For example, the representation encodes the shape of an anatomical structure as well as the variations within that structure. These variations are embedded in a vector space that relates to a probabilistic model. We apply our representation to a voxel based segmentation algorithm. We do so by embedding the manifold of Signed Distance Maps (SDM) into the linear space of LogOdds. The LogOdds variant is superior to the SDM model in an experiment segmenting 20 subjects into subcortical structures. We also use LogOdds in the non-convex interpolation between space conditioned distributions. We apply this model to a longitudinal schizophrenia study using quadratic splines. The resulting time-continuous simulation of the schizophrenic aging process has a higher accuracy then a model based on convex interpolation

Robust atlas-based segmentation of highly variable anatomy: left atrium segmentation

Automatic segmentation of the heart’s left atrium offers great benefits for planning and outcome evaluation of atrial ablation procedures. However, the high anatomical variability of the left atrium presents significant challenges for atlas-guided segmentation. In this paper, we demonstrate an automatic method for left atrium segmentation using weighted voting label fusion and a variant of the demons registration algorithm adapted to handle images with different intensity distributions. We achieve accurate automatic segmentation that is robust to the high anatomical variations in the shape of the left atrium in a clinical dataset of MRA images.National Alliance for Medical Image Computing (U.S.) (NIH NIBIB NAMIC U54-EB005149)Neuroimaging Analysis Center (U.S.) (NIH NCRR NAC P41-RR13218)National Institute of Neurological Disorders and Stroke (U.S.) (NIH NINDS R01-NS051826)National Institutes of Health (U.S.) (Grant R01EB008743-01A2)National Science Foundation (U.S.) (CAREER grant 0642971)Irwin Mark Jacobs and Joan Klein Jacobs Presidential FellowshipJulie Payette-NSERC Research Scholarshi

A generative model for brain tumor segmentation in multi-modal images

We introduce a generative probabilistic model for segmentation of tumors in multi-dimensional images. The model allows for different tumor boundaries in each channel, reflecting difference in tumor appearance across modalities. We augment a probabilistic atlas of healthy tissue priors with a latent atlas of the lesion and derive the estimation algorithm to extract tumor boundaries and the latent atlas from the image data. We present experiments on 25 glioma patient data sets, demonstrating significant improvement over the traditional multivariate tumor segmentation

Mri tissue classification with neighborhood statistics: A nonparametric, entropy-minimizing approach

Abstract. We introduce a novel approach for magnetic resonance image (MRI) brain tissue classification by learning image neighborhood statistics from noisy input data using nonparametric density estimation. The method models images as random fields and relies on minimizing an entropy-based metric defined on high dimensional probability density functions. Combined with an atlas-based initialization, it is completely automatic. Experiments on real and simulated data demonstrate the advantages of the method in comparison to other approaches.

Determination of relationships among autochthonous grapevine varieties (Vitis vinifera L.) in the Northwest of the Iberian Peninsula by using microsatellite markers

Fifty six grapevine varieties traditionally grown in the Northwest region of the Iberian Peninsula were analysed for six microsatellite loci, in order to determine the relationships among them as well as the plant material that should be collected and preserved in germplasm banks. Previous morphological and molecular results were taken into account for assessment of the existing synonymies among accessions from different European countries. Percent distribution of the main alleles was calculated. Multivariate analysis was carried out and similarities among the studied material were described and commented.This work has been partially supported by the INIA (Spain) RF02-004-C5-1 project.Peer reviewe

Acesso vascular para hemodiálise com cateter temporário de duplo lúmen em cães com insuficiência renal aguda Hemodialysis vascular access with temporary double-lumen catheter in dogs with acute renal failure

A hemodiálise é uma modalidade terapêutica que pode sustentar a vida do paciente com insuficiência renal aguda (IRA), enquanto este recupera a função renal. Para sua realização, é necessário estabelecer circulação extracorpórea, para que seja realizada a filtração do sangue, impondo a necessidade de um acesso vascular viável e eficiente. O objetivo deste estudo foi avaliar a eficiência e as complicações do acesso vascular para hemodiálise (HD), com cateter temporário de duplo lúmen inserido na veia jugular externa. Foram estudados 10 cães com IRA induzida por gentamicina, submetidos a sessões diárias de HD, com duração de uma hora, até a recuperação da função renal ou óbito. Foram realizadas 104 sessões de HD nos animais estudados, observando-se necessidade de troca do cateter em sete sessões (6,7%), devido à obstrução do lúmen do cateter em seis sessões (5,8%) ou por saída acidental do mesmo em uma sessão (1,0%). Não se observou migração do cateter, infecção, hemorragia ou hematoma no local de entrada do cateter na pele, obtendo-se fluxo sanguíneo patente em 90,4% das sessões. Concluiu-se que o acesso vascular na veia jugular externa com cateter temporário de duplo-lúmen mostrou-se viável, com ocorrência de poucas complicações, sendo, portanto, indicado como forma de acesso para a circulação extracorpórea para HD em cães com IRA.<br>Hemodialysis is a therapeutic procedure that can sustain the patient's life in acute renal failure (ARF), during the renal function recover. To perform hemodialysis (HD), an extracorporeal circulation is established to blood filtration, imposing the need of a viable and efficient vascular access. The aim of this study was to evaluate the effectiveness and complications of the HD vascular access with temporary double-lumen catheter inserted into the external jugular vein. Ten mongrel dogs with ARF, induced by gentamicin administration, were submitted to daily hemodialysis for one hour, until renal function recover or death. A total of 104 HD sessions were performed. Catheter replacement was accomplished in seven sessions (6.7%), due to catheter lumen mechanical obstruction in six sessions (5.8%) or accidental catheter output in one session (1.0%). No catheter migration, infection, bleeding or haematoma around the catheter insertion site was found. Effective blood flow rates were observed in 90.4% HD sessions. In conclusion, the vascular access in jugular external vein with temporary double-lumen catheter was valuable, with few complications, and should be indicated to vascular access in extracorporeal circulation to HD in ARF dogs