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Abstract

Minimally invasive procedures for the kidney tumour removal require a 3D visualization of topological relations between kidney, cancer, the pelvicalyceal system and the renal vascular tree. In this paper, a novel methodology of the pelvicalyceal system segmentation is presented. It consists of four following steps: ROI designation, automatic threshold calculation for binarization (approximation of the histogram image data with three exponential functions), automatic extraction of the pelvicalyceal system parts and segmentation by the Locally Adaptive Region Growing algorithm. The proposed method was applied successfully on the Computed Tomography database consisting of 48 kidneys both healthy and cancer affected. The quantitative evaluation (comparison to manual segmentation) and visual assessment proved its effectiveness. The Dice Coefficient of Similarity is equal to 0.871 ± 0.060 and the average Hausdorff distance 0.46 ± 0.36 mm. Additionally, to provide a reliable assessment of the proposed method, it was compared with three other methods. The proposed method is robust regardless of the image acquisition mode, spatial resolution and range of image values. The same framework may be applied to further medical applications beyond preoperative planning for partial nephrectomy enabling to visually assess and to measure the pelvicalyceal system by medical doctors.
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Abstract

With development of medical diagnostic and imaging techniques the sparing surgeries are facilitated. Renal cancer is one of examples. In order to minimize the amount of healthy kidney removed during the treatment procedure, it is essential to design a system that provides three-dimensional visualization prior to the surgery. The information about location of crucial structures (e.g. kidney, renal ureter and arteries) and their mutual spatial arrangement should be delivered to the operator. The introduction of such a system meets both the requirements and expectations of oncological surgeons. In this paper, we present one of the most important steps towards building such a system: a new approach to kidney segmentation from Computed Tomography data. The segmentation is based on the Active Contour Method using the Level Set (LS) framework. During the segmentation process the energy functional describing an image is the subject to minimize. The functional proposed in this paper consists of four terms. In contrast to the original approach containing solely the region and boundary terms, the ellipsoidal shape constraint was also introduced. This additional limitation imposed on evolution of the function prevents from leakage to undesired regions. The proposed methodology was tested on 10 Computed Tomography scans from patients diagnosed with renal cancer. The database contained the results of studies performed in several medical centers and on different devices. The average effectiveness of the proposed solution regarding the Dice Coefficient and average Hausdorff distance was equal to 0.862 and 2.37 mm, respectively. Both the qualitative and quantitative evaluations confirm effectiveness of the proposed solution.
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Abstract

The aim of this study was to determine whether the serum concentration of the phosphate (Pi) and the Ca x P value correlate with the IRIS stage of chronic kidney disease (CKD) in cats and, thus, whether they can be used as markers of the disease progression. Another aim was to assess whether the concentration of Ca in blood needs to be corrected based on the albumin concentration. The study was performed on 165 cats divided into five groups: the healthy group – C and study groups: I, II, III and IV with cats assigned to the groups based on the IRIS scale. Blood was collected from all the animals. The product of Ca x Pi, Cacorr and the product of Cacorrx Pi were calculated based on the obtained results. Despite no differences between groups I-III, there was a clear upward trend in the Pi concentration, in the Ca x Pi and in the Cacorr x Pi with CKD progression. In group IV, the Pi concentration and the Ca x Pi as well as the Cacorr x Pi value were significantly higher than the other groups. The concentration of Ca and its albumin-corrected serum values did not differ significantly. The serum concentration of Pi and the Ca x P product cannot be used as indicators of CKD progression in cats, but they may be used as additional elements in the diagnosis of stage IV CKD. The results also suggest that the serum calcium concentrations do not need to be albumin-corrected in cats.
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