Patterns of vascular graft infection in 18F-FDG PET/CT

BACKGROUND: 18F-FDG PET/CT has become an important tool in diagnosis of prosthetic vascular graft infections (PVGI). The aim of the study was to identify the patterns of vascular graft infection in 18F-FDG PET/CT. MATERIAL AND METHODS: The study was performed in 24 patients with vascular graft infection, in 17 patients implanted in an open surgery mode and in 7 patients by endovascular aortic repair (EVAR). Vascular prostheses were evaluated by two visual scales and semi-quantitative analysis with maximum standardized uptake values (SUV max). RESULTS: In the 3-point scale: 23 patients were in grade 1 and one patient was in grade 2. In the 5-point scale: 19 patients were in grade 5 with the highest activity in the focal area, 4 patients were in grade 4 and one patient in grade 3. The visual evaluation of 18F-FDG PET/CT study revealed that peri-graft high metabolic activity was associated with occurrence of morphological abnormalities (n = 21) like gas bubbles and peri-graft fluid retention or without abnormal CT findings (n = 3). The presence of the gas bubbles was linked to higher uptake of 18F-FDG (p < 0.01, SUVmax 11.81 ± 4.35 vs 7.36 ± 2.80, 15 vs 9 pts). In EVAR procedure, the highest metabolic activity was greater than in classical prosthesis (SUVmax 21.5 vs 13). CONCLUSIONS: 18F-FDG PET/CT is a very useful tool for assessment of vascular graft infections. CT findings like gas bubbles, or peri-graft fluid retention were associated with significantly higher glucose metabolism; however, in some cases without anatomic alterations, increased metabolic activity was the only sign of infection

CUDA accelerated Medical Segmentation metrics with MedEval3D

Medical segmentation metrics are crucial for development of correct segmentation algorithms in medical imaging domain. In case of three dimensional large arrays representing studies like CT, PET/CT or MRI of critical importance is availability of library implementing high performance metrics. MedEval3D is created in order to fulfill this need thanks to implementation of CUDA acceleration. Most of implemented metrics like Dice coefficient, Jacard coefficient etc. are based on confusion matrix, what enable effective reuse of calculations across multiple metrics improving performance in such use case. Additionally algorithms like interclass correlation and Mahalanobis distance are also introduced. In both cases their implementations are significantly faster then their counterparts from other available libraries. Lastly programming interface to all of the metrics was created in Julia programming language

Drgania a wykrywanie uszkodzenia w belkach kompozytowych

In this work, the geometrically nonlinear vibrations of composite beams subjected to harmonic loading and thermal changes are used to study the sensitivity of selected vibration response parameters to the presence of damage (delamination). The damage detection criterion formulated earlier for non-heated plates, based on analysing the points in the Poincaré sections of the damaged and healthy plate, is modified and tested for the case of beams additionally subjected to elevated temperatures. The mportance of the actual temperature in the process of damage detection is shown.W niniejszej pracy omówiono wykorzystanie drgań nieliniowych belek kompozytowych, poddanych wymuszeniom harmonicznym i obciążeniom cieplnym, do celów wykrywania uszkodzenia (delaminacji). Przestudiowano czułość wybranych parametrów opisujących dynamiczną odpowiedź układu na obecność wady w strukturze. Kryterium uszkodzenia, sformułowane we wcześniejszych pracach autorów dla niepodgrzewanych płyt, oparte na porównywaniu map Poincaré dla płyty zdrowej oraz uszkodzonej, zostało zmodyfikowane i przetestowane na strukturach belkowych. W modelach numerycznych belek zastosowano dodatkowo działanie podwyższonej temperatury. Pokazano w ten sposób istotne znaczenie temperatury na proces wykrywania uszkodzenia. Zaprezentowano także pierwsze wyniki badań doświadczalnych

Dynamics of a laminated composite beam with delamination and inclusions

In this work numerical and experimental study of the dynamic behaviour of a composite laminated beam having delamination is presented. The model of delamination takes into account a contact interaction between sublaminates including normal forces, shear forces and additional damping. In order to verify the model special samples of multilayered beams have been manufactured. Small parts of adjacent layers have been cut and replaced by inclusions from different materials modelling delamination. The mechanical properties of the inclusions have been considered during the numerical calculations. The beams were subjected to a short pulse loading and then their response was registered. The results from the numerical simulation were in a good agreement with the experimental results. The significance of the additional damping due to delamination on the response of the beam was confirmed numerically and experimentally