Edge- and detail-preserving sparse image representations for deformable registration of chest MRI and CT volumes

Deformable medical image registration requires the optimisation of a function with a large number of degrees of freedom. Commonly-used approaches to reduce the computational complexity, such as uniform B-splines and Gaussian image pyramids, introduce translation-invariant homogeneous smoothing, and may lead to less accurate registration in particular for motion fields with discontinuities. This paper introduces the concept of sparse image representation based on supervoxels, which are edge-preserving and therefore enable accurate modelling of sliding organ motions frequently seen in respiratory and cardiac scans. Previous shortcomings of using supervoxels in motion estimation, in particular inconsistent clustering in ambiguous regions, are overcome by employing multiple layers of supervoxels. Furthermore, we propose a new similarity criterion based on a binary shape representation of supervoxels, which improves the accuracy of single-modal registration and enables multi-modal registration. We validate our findings based on the registration of two challenging clinical applications of volumetric deformable registration: motion estimation between inhale and exhale phase of CT scans for radiotherapy planning, and deformable multi-modal registration of diagnostic MRI and CT chest scans. The experiments demonstrate state-of-the-art registration accuracy, and require no additional anatomical knowledge with greatly reduced computational complexity. © 2013 Springer-Verlag

The economic impact of foot and mouth disease and its control in South-East Asia: A preliminary assessment with special reference to Thailand

A pilot study of the economic impact of foot and mouth disease (FMD) in the countries and region of South-East Asia is described. Previous economic impact assessments are reviewed and summarised and a synthesis of these contributions is constructed. A framework for the future economic impact of the disease is then developed, incorporating analyses at the sectorl (production system), national and regional levels. Data requirements for such studies are also identified. Integrated epidemiological and economic models for impact assessment were developed and applied to the case study country of Thailand. The models were used to evaluate the economic viability of FMD control programmes in the country. Scenarios evaluated include the effect of improving vaccination coverage and thus reducing productivity losses, and the effect of eventual eradication of the disease. The results indicate that economic returns to the high expenditures incurred in FMD control could be achieved in the shorterm if greater international trade in pork products was made possible and export prices higher than those in the domestic market could be attained. If FMD were to be eradicated from Thailand in 2010, the eradication would be economically viable, even without exports, with a predicted benefit-cost ratio of 3.73. With additional exports, the economic justification for control becomes much stronger with a benefit-cost ratio of up to 15.1 being achieved. If eradication is not achieved until 2020, returns remain positive without exports, but at a lower rate. The authors propose that the integrated epidemiological and economic models developed be applied to other countries of the region to gain a more accurate insight into the future benefits of FMD control and eradication in the region

Subcortical band heterotopia (SBH) in males: clinical, imaging and genetic findings in comparison with females

Subcortical band heterotopia (SBH) or double cortex syndrome is a neuronal migration disorder, which occurs very rarely in males: to date, at least 110 females but only 11 in males have been reported. The syndrome is usually associated with mutations in the doublecortin (DCX) (Xq22.3-q23) gene, and much less frequently in the LIS1 (17p13.3) gene. To determine whether the phenotypic spectrum, the genetic basis and genotype-phenotype correlations of SBH in males are similar to those in females, we compared the clinical, imaging and molecular features in 30 personally evaluated males and 60 previously reported females with SBH. Based on the MRI findings, we defined the following band subtypes: partial, involving one or two cerebral lobes; intermediate, involving two lobes and a portion of a third; diffuse, with substantial involvement of three or more lobes; and pachygyria-SBH, in which posterior SBH merges with anterior pachygyria. Karyo typing and mutation analysis of DCX and/or LIS1 were performed in 23 and 24 patients, respectively. The range of clinical phenotypes in males with SBH greatly overlapped that in females. MRI studies revealed that some anatomical subtypes of SBH, such as partial and intermediate posterior, pachygyria-SBH and diffuse bands with posterior predominance, were more frequently or exclusively present in males. Conversely, classical diffuse SBH and diffuse bands with anterior predominance were more frequent in females. Males had either mild or the most severe band subtypes, and these correlated with the over-representation of normal/borderline intelligence and severe mental retardation, respectively. Conversely, females who had predominantly diffuse bands exhibited mostly mild or moderate mental retardation. Seven patients (29%) had missense mutations in DCX; in four, these were germline mutations, whereas in three there was evidence for somatic mosaicism. A germline missense mutation of LIS1 and a partial trisomy of chromosome 9p were identified in one patient (4%) each. One male each had a possible pathogenic intronic base change in both DCX and LIS1 genes. Our study shows that SBH in males is a clinically heterogeneous syndrome, mostly occurring sporadically. The clinical spectrum is similar to that of females with SBH. However, the greater cognitive and neuroradiological heterogeneity and the small number of mutations identified to date in the coding sequences of the DCX and LIS1 genes in males differ from the findings in females. This suggests other genetic mechanisms such as mutations in the non-coding regions of the DCX or LIS1 genes, gonadal or somatic mosaicism, and finally mutations of other gene