Hippocampus volumes have been shown to be decreased in patients with major depression, but volume measurements are inconsistent in patients with bipolar disorder. Both disorders are associated with deficits in hippocampus-mediated cognitive functions. However, the underlying pathophysiology is widely unknown. In this post-mortem study, we used design-based stereology on Nissl-stained serial sections to investigate the number of neurons, oligodendrocytes and astrocytes in substructures of the posterior hippocampus in eight patients with major depression, eight patients with bipolar disorder and ten control patients without a neuropsychiatric disorder. Compared to controls, patients with bipolar disorder had significantly more neurons in the cornu ammonis subfield 1 (CA1) and the subiculum, while the number of oligodendrocytes was higher only in CA1. In patients with major depression, the density of oligodendrocytes was higher in CA2/3, CA4 and the subiculum. The dose of antidepressants correlated with the density and number of oligodendrocytes in CA2/3, indicating that antidepressants may affect our results. Treatment with neuroleptics expressed in chlorpromazine equivalents and benzodiazepines expressed in diazepam equivalents correlated negatively with the number of oligodendrocytes in CA2/3 and CA4, respectively, suggesting that treatment with these drugs do not influence cell number. We did not detect alterations in either volumes of substructures or numbers of astrocytes. Increased cell numbers argue for a denser packing of neurons and oligodendrocytes as a result of a decreased neuropils. This neuropathological process may be based on neurodevelopmental disturbances and may contribute to altered microconnectivity and cognitive deficits in affective disorders.
Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm’s results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each other). As evaluation metric for the statistical validation, the Dice Similarity Coefficient (DSC) has been calculated. The results show that the proposed tool provides lesion segmentation with sufficient accuracy much faster than manual segmentation. The visual feedback and interactivity make the proposed tool well suitable for the clinical workflow.
In this contribution, we present a semi-automatic segmentation algorithm for radiofrequency ablation (RFA) zones via optimal s-t-cuts. Our interactive graph-based approach builds upon a polyhedron to construct the graph and was specifically designed for computed tomography (CT) acquisitions from patients that had RFA treatments of Hepatocellular Carcinomas (HCC). For evaluation, we used twelve post-interventional CT datasets from the clinical routine and as evaluation metric we utilized the Dice Similarity Coefficient (DSC), which is commonly accepted for judging computer aided medical segmentation tasks. Compared with pure manual slice-by-slice expert segmentations from interventional radiologists, we were able to achieve a DSC of about eighty percent, which is sufficient for our clinical needs. Moreover, our approach was able to handle images containing (DSC=75.9%) and not containing (78.1%) the RFA needles still in place. Additionally, we found no statistically significant difference (p<;0.423) between the segmentation results of the subgroups for a Mann-Whitney test. Finally, to the best of our knowledge, this is the first time a segmentation approach for CT scans including the RFA needles is reported and we show why another state-of-the-art segmentation method fails for these cases. Intraoperative scans including an RFA probe are very critical in the clinical practice and need a very careful segmentation and inspection to avoid under-treatment, which may result in tumor recurrence (up to 40%). If the decision can be made during the intervention, an additional ablation can be performed without removing the entire needle. This decreases the patient stress and associated risks and costs of a separate intervention at a later date. Ultimately, the segmented ablation zone containing the RFA needle can be used for a precise ablation simulation as the real needle position is known.
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