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Kidney Segmentation in CT Data Using Hybrid Level-Set Method with Ellipsoidal Shape Constraints

Skalski A., Heryan K., Jakubowski J., Drewniak T.

Metrology and Measurement Systems

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2017

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Vol. 24, nr 1

101--112

EN

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.

2

Automatic Extraction of the Pelvicalyceal System for Preoperative Planning of Minimally Invasive Procedures

Heryan K., Skalski A., Jakubowski J., Drewniak T., Gajda J.

Metrology and Measurement Systems

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2017

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Vol. 24, nr 1

3--18

EN

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.

3

Zastosowanie metody zbiorów poziomicowych do wyodrębniania struktur naczyniowych w obrębie nerki w celu minimalizacji inwazyjności zabiegów onkologicznych

Bugajska K., Skalski A., Drewniak T., Gajda J.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 5

68-71

PL

W artykule zaproponowano zastosowanie algorytmów przetwarzania obrazów w celu wyodrębnienia struktur naczyniowych zlokalizowanych w obrębie nerki. Możliwość identyfikacji tętnic odżywiających guza nerki pozwala na jego usunięcie bez ryzyka wystąpienia urazu niedokrwiennego i przyczynia się do maksymalnego zabezpieczenia czynności nerki. Minimalizacja inwazyjności zabiegu usunięcia guza jest także korzystna dla pacjenta. Badania rozpoczęto od segmentacji struktur naczyniowych preparatów anatomicznych. Do ich wyodrębnienia zastosowano progowanie z histerezą, co pozwoliło na otrzymanie funkcji inicjalizującej dla metody zbiorów poziomicowych. Otrzymane wyniki potwierdziły skuteczność doboru metody - wizualnie ciągłość tych struktur była lepiej odtworzona względem samej binaryzacji, a granice obiektów były odpowiednio odwzorowane. Dodatkowo, analiza ilościowa polegająca na porównaniu otrzymanych wyników działania algorytmu z ręcznymi obrysami okazała się zadawalająca, co skłania do kontynuacji badań mogących stanowić o renoprotekcji.

EN

In the article we have proposed an application of several image processing algorithms to extract renal vessels. Earlier identification of the tumor feeding arteries facilitates conducting a zero-ischemia partial nephrectomy and preservation of renal function. This minimally invasive procedure is also beneficial for a patient. The study began with vascular structures segmentation of anatomical preparations. To do this hysteresis thresholding was applied to three dimensional computer tomography images. It allowed to obtain an initialization function for subsequently applied segmentation method – i.e. the level set method. The results confirmed the effectiveness of described methods - visually, in comparison to initial binarization, the acquired structures continuity had been found better and the objects boundaries were properly mapped. In addition, quantitative analysis involving the comparison of segmentation results with manual ones had been found satisfactory, that encourages to continue further research.

4

Experimental analysis of aerodynamic performance of flapping wings nano aerial vehicles

Czekałowski P., Drewniak T., Sibilski K., Żyluk A.

Journal of KONES

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2014

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Vol. 21, No. 3

47--57

EN

The aerodynamics of flapping wings is ultimately concerned with the relation between motion kinematics and the time-history of aerodynamic forces and moments. However, an important intermediate quantity is the evolution of the flow field – and in particular of flow separation. Nature’s solution to large time-varying pressure gradients, for example those due to aggressive motions, is to form and eventually to shed vortices. We are interested in understanding and exploiting these vortices – for example, in delaying vortex shedding to promote lift in situations where flow separation is in any case inevitable. From the engineering viewpoint, the question is to what extent closedform models and conventional numerical/analytical tools can estimate the aerodynamic force history, with an eye to eventually running large parameter studies and optimizations. Our paper contains results of water tunnel experiments on flapping wings aeromechanics. The idea of investigation is to optimize the wing trajectories, and to find methods providing stability and control. In the paper, we present, also, conception and methodology of tests. The investigation is dividing into two parts: preliminary and principal tests. The aim of initial part is to extract quasi – state characteristic for wings of different platforms shapes. This characteristic will be used to generate initial kinematics of movement of wing. It will be initial point of further tests. The purpose of the main experiment is to find the best way of movement for wing taking account all of unsteady phenomena (interaction between vortices, wing – wing interference, etc.). Finally, we want to identify efficient way of controlling nano-microelectromechanical flying insect (entomopter).