8,863 research outputs found
METODI PER L’ANALISI DELLA TEXTURE DI REGIONI DI INTERESSE (ROIs) DI FORMA IRREGOLARE PER IMMAGINI BIOMEDICHE
No full textIn questa tesi sono presentati algoritmi per le stime, in ROIs irregolari di immagini a scale di grigio, della dimensione frattale(DF) e di indici per la caratterizzazione dei loro istogrammi.
Tali strumenti sono stati testati in due lavori.
Il primo riguarda un nuovo metodo di valutazione dell’hepato-renal ratio(HRR) per la valutazione quantitativa della steatosi epatica con immagini ecografiche. L’HRR è stato definito come il rapporto dell’intensità media di due ROIs rispettivamente del fegato e del rene. Il metodo proposto prevede la selezione di ROIs a “mano libera”(ROIs fh).Le ROIs sono quindi sottoposte a pre-processing(PP), consistente nella“normalizzazione delle ROIs”,per rendere le due aree più comparabili, e nello smoothing dei relativi istogrammi normalizzati.L’HRR è stato calcolato sulla base del PP delle ROIs. Per testare l’efficacia del PP, il procedimento è stato ripetuto da un secondo operatore con ROIs di forma ellittica o circolare(ROIs e/c).Il dataset analizzato è di 98 scansioni di 32 pazienti(23 pazienti con più scansioni).L’efficacia della tecnica è stata valutata confrontandola con un metodo(metodo di riferimento,MR)sviluppato sulla base di precedenti lavori. La variabilità inter-scansione è stata valutata calcolando il massimo tra i valori assoluti delle differenze degli HRRs delle scansioni di uno stesso paziente. Gli HRRs ottenuti con il PP delle ROIs non hanno mostrato differenze significative rispetto a quelli ottenuti con il MR(p-value=0.52 per ROIs fh e p-value=0.14 per ROIs e/c).Un analogo risultato è stato conseguito nel confronto tra gli HRRs ottenuti dal PP delle ROIs e/c e quelli risultanti dal PP delle ROIs fh,(p-value=0.46).Il metodo presentato(con PP di ROIs fh )ha mostrato una variabilità inter-scansione minore del MR(p-value<0.001).I risultati preliminari sembrano confermare che il metodo proposto è riproducibile ed ha un’efficacia clinica comparabile al MR.
L’oggetto del secondo lavoro è la valutazione quantitativa delle alterazioni ecografiche dello sfintere anale interno(IAS) associate l’invecchiamento.62 soggetti sani di età tra i 19 e gli 87anni sono stati sottoposti a endosonografia anale 3D.La parte mediale dell’IAS è stata valutata con misurazioni di volume, dell’intensità mediana(IM) e della DF.L’età dei soggetti è stata rappresentata attraverso una variabile a tre livelli(19-59, 60-69 e 70-87anni).Per lo studio delle associazioni tra l’età e le caratteristiche dell’IAS è stata impiegata la “path analysis”(PA).L’IM e la DF sono state incluse nella PA come potenziali mediatori dell’effetto dell’età sul volume se, nell’analisi descrittiva, essi mostravano un andamento crescente con l’età. L’associazione tra ogni coppia di variabili è stata espressa mediante il rapporto tra i valori attesi(REV:1=nessuna associazione,1=associazione positiva).Nell’analisi descrittiva, contrariamente all’IM ed al volume, la DF non ha mostrato un andamento crescente con l’età ed è stata quindi esclusa dalla PA.Nella PA, l’IM ha mostrato un aumento significativo solo tra i soggetti più anziani e quelli più giovani(70-87vs.19-59anni,REV=1.21, p-value=0.048).È stato osservato solo un effetto diretto dell’età sul volume(60-69vs.19-59anni,REV=1.21, p-value=0.070 e 70-87vs.19-59anni,REV=1.32,p-value=0.015).L’IM appare efficace nel rilevare alterazioni della texture dell’IAS legate all’invecchiamento.I risultati ottenuti, sembrano non supportare l’ipotesi di un’associazione tra il processo di fibrosi dell’IAS legato all’invecchiamento e l’aumento di volume muscolare legato all’età.
In entrambi i lavori la verifica dei risultati ottenuti,e/o delle relative interpretazioni, richiederà ulteriori indagini con studi che validino le misurazioni ecografiche attraverso rilevazioni istologiche su un largo campione di soggetti.
I due studi sono esempi di come l’analisi della texture possa contribuire a realizzare nuovi strumenti clinici in grado di produrre valutazioni oggettive e quantitativeThis thesis presents algorithms for the assessment, in irregular gray scale image ROIs, of the fractal dimension (FD) and indices aimed at the characterization of the related histograms. The tools were tested by their applications in the two studies.
The first study shows the preliminary results obtained in the experimentation of a new method for liver steatosis quantification by means of ultrasound image analysis. This method is based on hepato-renal ratio (HRR) assessment. HRR was assessed as the ratio between the mean intensities of pixels belonging to two ROIs located respectively in the liver and the kidney. In the method outlined here, the operator selects two ROIs by “freehand”(fh ROIs).The ROIs were subsequently pre-processed, via “ROI normalization”, to make the two areas more comparable, and smoothing out the related normalized histograms. Then HRRs were calculated on the basis of the histograms obtained from pre-processing(PP). In order to test the efficacy of the PP, the procedure was repeated by a second operator, using elliptical and/or circular ROIs(e/c ROIs). The dataset comprised 98 images of 32 patients(for 23 patients more than one scan was performed). The efficacy of the technique presented was tested by comparison with a method developed on the basis of previous works. The HRRs obtained with ROIs pre-processing did not differ significantly from those of the reference method (for the fh ROIs and e/c ROIs the p-values were 0.52 and 0.14 respectively). A similar result was obtained by comparing the HRRs derived from the PP of the e/c ROIs and those resulting from the PP of fh ROIs (p- value=0.46).The method for HRR assessment presented here (on the basis of the PP of fh ROIs) gave a smaller inter-scan variability than the reference method (p-value<0.001). Preliminary results seem to confirm that the proposed method is reproducible and has clinical efficacy comparable to the reference method.
The second study aimed at the quantitative assessment of the ultrasound alterations of the internal anal sphincter(IAS), associated with aging. 62 healthy subjects aged between 19 and 87 underwent 3D endoanal ultrasonography. The medial part of the IAS was characterized by assessments of the volume, median voxel intensity (MI) and FD. The age of the subjects under analysis was classified as a three-level variable(19-59, 60-69 and 70-87years). The associations between age and IAS characteristics were evaluated by a path analysis(PA).The MI and the FD were included in the PA as potential mediators of the effect of age on the volume only if they showed an increasing trend according to aging by descriptive analysis. The association between each pair of variables was summarized using the ratio of expected values(REV: 1=no association, 1=positive association).In descriptive analysis, unlike for volume and MI, the FD did not show an increasing trend according to aging, therefore it was excluded from PA. In the PA, the MI showed a statistically significant difference between older and younger subjects only(70-87vs.19-59 years, REV= 1.21, p-value=0.048). Furthermore solely a direct positive effect of age on volume was observed(60-69 vs.19-59 years, REV=1.21, p-value=0.070 and 70-87vs.19-59 years, REV=1.32, p-value=0.015).The MI seems to be an appropriate measure of echotexture alterations in the IAS related to aging.The findings obtained appear not to support the hypothesis that there is an association between the age-related physiological process of fibrosis and a volume increase with age.
For both works presented, the results obtained and/or related interpretations require verification by further investigation via studies aimed at the validation of ultrasound assessments by histological findings, analyzing a large sample of subjects.
These studies are examples of how texture analysis can be used to provide new tools able to perform objective and quantitative assessments for clinical purpos
An Improved Method for Hepato-Renal Ratio Assessment: a Feasibility Study
No full textHepato-Renal Ratio (HRR) is a method for the quantitative assessment of liver steatosis based on the processing of ultrasound images. Its reliability has been validated in literature through biopsy and 1H magnetic resonance spectroscopy.This paper describes a new method for ROI segmentation and HRR assessment, designed to minimize both inter-observer and inter-scan variability
An improved method for hepato-renal ratio assessment in the diagnosis of hepatosteatosis: a feasibility study
No full textThe hepato-renal ratio is a non-invasive method for liver steatosis quantification based on ultrasound image analysis. Its effectiveness has been validated in literature by means of liver biopsy and 1H magnetic resonance spectroscopy. We propose a new and improved method for ROI selection and HRR assessment, designed to minimize both interobserver and inter-scan variability
The role of basophils as innate immune regulatory cells in allergy and immunotherapy
No full textBasophils are circulating cells that are associated quite exclusively with allergy response and hypersensitivity reactions but their role in the immune network might be much more intriguing and complex than previously expected. The feasibility of testing their biology in vitro for allergy research and diagnosis, due fundamentally to their quite easy availability in the peripheral blood, made them the major source for assessing allergy in the laboratory assay, when yet many further cells such as mast cells and eosinophils are much more involved as effector cells in allergy than circulating basophils. Interestingly, basophil numbers change rarely in peripheral blood during an atopic response, while we might yet observe an increase in eosinophils and modification in the biology of mast cells in the tissue during an hypersensitivity response. Furthermore, the fact that basophils are very scanty in numbers suggests that they should mainly serve as regulatory cells in immunity, rather than effector leukocytes, as still believed by the majority of physicians. In this review we will try to describe and elucidate the possible role of these cells, known as "innate IL4-producing cells" in the immune regulation of allergy and their function in allergen immunotherapy
The role of vitamin D in the immune system as a pro-survival molecule
No full textPURPOSE: Vitamin D is a fascinating and attractive molecule that has gained particular attention in medicine in recent years. Its immunomodulatory and anti-inflammatory potential might resemble the activity of many nature-derived molecules (eg, flavonoids), but its role in biology was selected during a long evolutionary pathway to dampen the damaging effect of cell stress response and of the immune reaction. In this sense, this molecule can be considered an ancient hormone that serves, in its primary role, as a pro-survival agent. The goal of this review was to elucidate this topic. METHODS: The article reviews current literature on the field, focusing on issues regarding the role of vitamin D in immunity. FINDINGS: Vitamin D participates in the survival machinery used by the cell, and in particular it plays a major role in synchronizing calcium oscillatory signaling to allow cell autophagy or apoptosis during a stress response. IMPLICATIONS: Vitamin D should be better highlighted in its molecular action and vitamin D receptor genomics to conceive a more suited therapeutic supplementation protocol in clinics
New method for internal anal sphincter measurements: Feasibility study
No full textThe aim of this paper is to provide a method for measuring the internal anal sphincter on the basis of the quantitative analysis of three-dimensional endosonographic images. A software calculates a large set of measurements which are able to describe the three-dimensional shape of the muscle. The software provides four types of measurements: thickness, length, area and volume. The different magnitudes are estimated using the same reference system. The measurements obtained are modeled by functions that describe their spatial tren
Andrea Bacová
No full textAndrea Bacová focuses on research and teaching in the field of residential architecture. Her work includes systematic research on residential buildings and their urban context. She actively participates in promoting Slovak architecture and is the author of several publications and exhibitions
Imaging of the Internal Anal Sphincter: Study of Healthy Subject: Review Article
No full textIntroduction: The internal anal sphincter is a smooth muscle that works with other muscles to control defecation. The identification of morphological changes, defects or the precise definition of the level of tumor infiltration of muscle have significant importance in clinical practice. For these reasons the evaluation of shape and volume of muscle in healthy subjects has been studied for many years. The main used imaging techniques are the anal endosonografy, the endoanal coil magnetic resonance imaging and the phase-array coil magnetic resonance. The small size of muscle, the high irregularity in shape, the variability associated with factors such as age and sex, the use of different imaging techniques, including non-invasive ones, and the lack of a standardized method of measurement, can make difficult the correct comparison of the results. In this chapter we will discuss the results reported in the literature concerning the evaluation of muscle in healthy subjects and the advantages and disadvantages of different methods adopted. Normal IAS Variations: Age-related variations:the thickening of the muscle associated to aging is particularly noticeable when the measurements is performed with the EAU and MR with endoanal coil. Sex-related variations: The characterization of the shape of the muscle in relation to sex appears to be controversial with all methods. The only common result is the greater length of the anterior quadrant in males when measured with the EAU. Variations related to other factors: In a study of nulliparous women with the EAU, it is reported a positive correlation between the thickness, measured in the mid anal canal, and BMI. By contrast, in a similar study carried out with MRI without the introduction of endoanal coil the average thickness of the muscle does not appear to be correlated with BMI. The thickness of the IAS in relation to height appears to increase with both methods of MR. Conclusion: The MRI allows a better visualization of the entirety of the pelvic perineal floor compared to EAU, which is extremely effective in imaging the IAS. Even the lower cost and facility and speed of EAU are the basis of most of the research with anal endosonografy. Normal range have been specifically formulated in only a few works for thickness and length. We believe that new studies and a process of standardization of methods of measurement could provide significant advances in the study of muscle either in a state of normality or pathology
Aesthetic Dentistry, How You Say and How You See: A 500-People Survey on Digital Preview and Color Perception
No full textPurpose: Digital technologies have improved ways to perform aesthetic dentistry in the last few years. The aims of this survey were to investigate the most preferred way to preview the result of an aesthetic dental rehabilitation among a population of dental professionals and laypeople and to compare aesthetic standards of the general population and dentists in terms of the color of teeth for aesthetic dental rehabilitations. Patients and Methods: A questionnaire was sent to the subjects (dentists and laypeople) during a 1-year period and, together with their demographic data, different ways to preview the result of an aesthetic rehabilitation were submitted, such as digital smile design, dental wax-up and oral explanation. Furthermore, an additional section of the questionnaire inves-tigated the most suitable color for an aesthetic rehabilitation based on the colors of the VITA Scale. Results were statistically analyzed (with Chi-square of independence and Mann– Whitney U-test) highlighting differences of answers based on age groups, educational attainment, gender, and belonging or not to the dental field. Results: Findings showed that digital smile design (digital preview) is a high-appreciated method for previewing and communicating with patients both by dental professionals and laypeople. Furthermore, lighter colors were found to be more valued by laypeople and significant differences were highlighted between the two populations assessed. Conclusion: It seems to be viable to use digital preview for dentists and laypeople to improve previewing and communicating ways. It might be advisable to better motivate patients in recognizing aesthetical features and to raise their awareness in preferring more mimetic aesthetic results. Great opportunities are opened up by digital smile design in teaching, learning, and routine practic
- …
