1,721,143 research outputs found
Effective shadow detection in traffic monitoring applications
No full textThis paper presents work we have done in detecting moving shadows in the context of an outdoor traffic scene for visual surveillance purposes. The algorithm just exploits some foreground photometric properties concerning shadows. The input of the system is constituted by the blobs previously detected and by the division image between the current frame and the background of the scene. The method proposed is essentially based on multi-gradient operations applied on the division image which aim to discover the most likely shadow regions. Further on, the subsequent “smart” binary edge matching we devised is performed on each blob’s boundary and permits to effectively discard those regions inside the blob which are either too far from the boundary or too small. We demonstrate the effectiveness of our method by using a gray level sequence taken from a sunny, daytime, traffic scene. Since no a priori knowledge is used in order to detect, and remove, shadows, this method represents one of the most general purpose systems to date for detecting outdoor shadows
MicroMos: an open source software tool to obtain high-resolution panoramic images of 2D cell cultures
No full textOBJECTIVE:
In order to perform significant analyses, the microscope’s user is typically interested in acquiring high-detailed images representing an entire histological sample or well containing cells. Due to the finite size of the camera’s field of view, the microscopist has to find the proper trade-off between higher magnification factor and extension of the observed area.
Here we present MicroMos version 3.0, an open-source tool for building mosaics by stitching together more partially overlapping images. The method proposed is based on visual information only and the mosaics are built by incrementally stitching couples of images. The radiance of the original sample is preserved by compensating the vignetting effect of each stitched image, and the mosaics obtained can be used for quantitative analyses.
By exploiting MicroMos we studied confluence and proliferation of mesenchymal stromal cells (MSC) adherent on OSPROLIFE (Eurocoating, Cirè-Pergine, Italy), a commercial biomaterial in the form of granules. In order to acquire statistically significant data we analysed mosaics built using MicroMos, implementing customized algorithms to segment the MSC and automatically estimate of the percentage of the area of the granules covered by cells.
MATERIALS AND METHODS:
To validate the proposed mosaicing method we performed several experiments under different working conditions. In particular, in order to assess the quality of the mosaics obtained using different warping models and tonal adjustments we used six different sets of images of histological samples and cell cultures. We aligned the images according to different registration models and computed several metrics to estimate which registration method performs as the best.
Then, to study confluence and proliferation of MSC adherent on OSPROLIFE granules, we prepared several samples each containing 50 mg of OSPROLIFE granules and a different number of MSC. Cell confluence was evaluated by adding 4 μM Calcein AM before acquiring sequence of partially overlapping images.
RESULTS:
In our experiments we tested different registration approaches, confirming quite unexpectedly that the translational model does not always act as the best, although the motion of the microscope’ sample holder is apparently translational. Indeed, the sample holder could be slightly inclined, hence yielding non-negligibly affine, or even projective, transformations between subsequent images.
CONCLUSION:
MicroMos version 3.0 is freely distributed as an open source tool, endowed with a graphical user interface, at the website: https://sourceforge.net/p/micromos/. Its usability makes building mosaics of microscope images at subpixel accuracy easier. Furthermore, optional parameters for building mosaics according to different strategies make MicroMos an easy and reliable tool to compare different registration approaches, warping models and tonal corrections. Finally, by analysing mosaics of granules at different time intervals we also obtained quantitative data regarding cell proliferation, confirming that MSC adhere onto the OSPROLIFE granules and proliferate over time
Letter to the Editor on “Comparative performance of fully-automated and semi-automated artificial intelligence methods for the detection of clinically significant prostate cancer on MRI: a systematic review”
Full text linkA Simple Self-Calibration Method To Infer A Non-Parametric Model Of The Imaging System Noise
No full textAnaSP: a software suite to automatically analyse spheroid used in high throughput experiments.
No full textL’eterogeneità perfusionale: un biomarker prognostico per il cancro del polmone non a piccole cellule (NSCLC)
No full textL’introduzione in oncologia di nuove terapie, in particolare quelle a bersaglio molecolare, ha condotto a notevoli progressi terapeutici, determinando miglior controllo del tumore, selettività terapeutica, ridotta tossicità. Tuttavia la prognosi per i pazienti affetti da tumore polmonare non a piccole cellule (NSCLC) in stadio avanzato risulta tuttora molto severa. Sebbene il più importante fattore prognostico sia attualmente costituito dallo stadio del tumore, la sopravvivenza di pazienti affetti da NSCLC e appartenenti allo stesso stadio risulta ampiamente variabile. Per queste ragioni, è necessario identificare marcatori prognostici più efficaci che siano in grado di stabilire quali tumori saranno sensibili o resistenti alle terapie. Questo condurrebbe ad una migliore gestione e stratificazione dei pazienti affetti da NSCLC, con notevoli implicazioni nella scelta dei trattamenti. L’analisi dell’eterogeneità neoplastica nei pazienti NSCLC, caratterizzata attraverso l’analisi strutturale mediante Tomografia Computerizzata (TC), ha mostrato notevoli potenzialità nel predire l’aggressività di un tumore. Anche più promettente è l’analisi dell’eterogeneità funzionale in grado di mettere in luce non solo le anomalie strutturali ma anche le disomogeneità funzionali presenti all’interno di un tumore. Tra le tecniche di imaging funzionale, particolare rilievo sta assumendo la TC perfusionale (TCp), che permette l’identificazione di pattern vascolari anomali, consentendo una valutazione precoce della risposta alle terapie citostatiche. In questo lavoro retrospettivo, valutiamo se alcuni indicatori, calcolabili a partire dalle mappe di valori perfusionali ottenute tramite TCp, possano essere utilizzati come marcatori prognostici. I risultati rilevano una coppia di indicatori in grado di separare pazienti affetti da NSCLC con diversa aspettativa di sopravvivenza. Viene confermata la comune aspettativa che una maggiore eterogeneità correli con una maggiore aggressività, riflettendosi gravemente sulla sopravvivenza dei pazienti. Si può quindi concludere che la misura emodinamica dell’eterogeneità tumorale rappresenti un significativo e oggettivo fattore prognostico, con possibili ricadute cliniche della TCp
Cancer multicellular spheroids: Volume assessment from a single 2D projection
No full textVolume is one of the most important features for the characterization of a tumour on a macroscopic scale. It is often used to assess the effectiveness of care treatments, thus mak-ing its correct evaluation a crucial issue for patient care. Similarly, volume is a key feature ona microscopic scale. Multicellular cancer spheroids are 3D tumour models widely employedin pre-clinical studies to test the effects of drugs and radiotherapy treatments. Very fewmethods have been proposed to estimate the tumour volume arising from a 2D projectionof multicellular spheroids, and even fewer have been designed to provide a 3D reconstruc-tion of the tumour shape. In this work, we propose Reconstruction and Visualization from aSingle Projection (ReViSP), an automatic method conceived to reconstruct the 3D surface andestimate the volume of single cancer multicellular spheroids, or even of spheroid cultures.As the input parameter ReViSP requires only one 2D projection, which could be a widefieldmicroscope image. We assessed the effectiveness of our method by comparing it with otherapproaches. To this purpose, we used a new strategy that allowed us to achieve accuratevolume measurements based on the analysis of home-made 3D objects, built by mimickingthe spheroid morphology. The results confirmed the effectiveness of our method for both3D reconstruction and volume assessment. ReViSP software is distributed as an open source tool
Multislice analysis of blood flow values in CT perfusion studies of lung cancer
No full textObjectives: Tumour heterogeneity represents a key issue in CT perfusion (CTp), where all studies are usually based on global mean or median values of perfusion maps, often computed on whole tumour. We sought to determine whether, and to what extent, such global values can be representative of tumour heterogeneity, with respect to single slices, and could be used for therapy assessment.
Materials and Methods: Twelve patients with one primary non-small cell lung cancer lesion were enrolled in this study, for a total amount of 26 CTp examinations and 118 slices. Mean and median blood flow (BF) values, calculated voxel-based, were computed on each slice and the whole tumour. To measure functional heterogeneity, entropy was calculated on BF values as well.
Results: Most of the slices were not represented by the global BF values computed on the whole tumour. In addition, there is a number of lesions having equivalent global BF values, but composed by slices having very different heterogeneity distributions, that is, entropy values.
Conclusions: Global mean/median BF values of the single slices separately should be considered for clinical assessment, only if interpreted through entropy computed on BF values. The numerical equivalence between global BF values of different lesions may correspond to different clinical status, thus inducing possible errors in choice of therapy when considering global value only
An Effective Real-Time Mosaicing Algorithm Apt to Detect Motion Through Background Subtraction Using a PTZ Camera
No full textDCE-CT in lung cancer: perfusion characterisation of adenocarcinoma and squamous carcinoma subtypes
No full textPurpose: To evaluate tumour baseline characteristics in blood flow (BF) values of two lung cancer subtypes, adenocarcinoma (AC) and squamous cell carcinoma (SCC). In addition, since literature shows discordant results, we also investigate possible motivations, so as to find out a clearer outcome.
Methods and Materials: 27 patients (age range 36-81 years) with primary NSCLC, subdivided into 20 AC and 7 SCC, were enrolled in this study and underwent a CT perfusion at the diagnosis stage. BF values were computed according to the maximum slope method and values undergoing high fitting errors were automatically removed. The one-tail Welch's t-test (p<0.001) was employed for statistical assessment.
Results: At baseline, mean BF values of AC group [81.4±30.1] result significantly greater than those of SCC subtype [59.6±31.7] (p<<10-5). Excluding unreliable BF values enforced the outcome. However, a few cases deviate from the mean value of the corresponding histological group. Two SCC lesions present a higher perfusion because of beam hardening artefacts coming from the pulmonary artery. Analogously, four AC cases show a lower perfusion, two of which are large and central lesions. The others, in the subpleural parenchyma, have a predominant pulmonary component underestimated by a delayed acquisition.
Conclusion: At diagnosis, AC histological type has a significantly greater perfusion than SCC one. This clear behaviour may be attenuated by lesion position, central or peripheral, pulmonary artery artefacts and not appropriate acquisition protocol. Although these findings are clear, they should be enforced by a larger dataset, being of relevant importance for treatment strategies
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