Ultrasound (US) is the first-line investigation in patients with abdominal symptoms and it has a role in the diagnosis and monitoring of inflammatory bowel diseases. Strain elastography (SE) is a US method for estimating tissue elasticity. This method is still not routinely used in clinical practice, although it is suggested by the EFSUMB Guidelines for the characterization of intestinal stenosis in Crohn's disease. The purpose of this Pictorial Essay is to confirm the feasibility of elastography in Crohn's disease in clinical practice by comparing elastography images with corresponding endoscopic or radiological images. At present, diagnostic accuracy of SE is reported in the literature only in connection with detection of bowel wall fibrosis in advanced cases of Crohn's disease. However, in our opinion, SE can add useful diagnostic information to grayscale and color Doppler US by providing a more accurate characterization of the bowel wall in the various manifestations of Crohn's disease.
Strain elastography is a recently developed ultrasound method that seems to contribute to the diagnosis and monitoring of inflammatory bowel diseases. This pictorial essay aims to present the feasibility of strain elastography in clinical practice by comparing visual observation and semiquantitative parameters with endoscopic or radiological images in some common cases of Crohn's disease. In our opinion, strain elastography with visual observation is easily performed in connection with B-mode ultrasound and color Doppler imaging and may provide relevant information. Strain elastography with the elaboration of semiquantitative parameters is not as immediate as the visual observation method, but it seems to provide more objective data and seems more appropriate for monitoring the evolution of the disease. However, for the elastographic method to extensively contribute in inflammatory bowel diseases, standardization and further studies are required to confirm the promising results already reported in the literature. Keywords Gastrointestinal ultrasound • Strain elastography • Bowel strain elastography • Crohn's disease SOMMARIO L'elastografia Strain è una recente metodica ecografica che sembra avere un ruolo nella diagnosi e nel monitoraggio delle malattie infiammatorie intestinali. Lo scopo di questo Pictorial Essay è di verificare la fattibilità dell'elastografia Strain nella pratica clinica confrontando l'osservazione visiva e i parametri semi-quantitativi con immagini endoscopiche o radiologiche in alcuni casi comuni di malattia di Crohn. A nostro parere, l'elastografia strain con osservazione visiva è facilmente eseguibile in connessione con l'ecografia B-mode ed il color Doppler e può fornire informazioni rilevanti. L'elastografia strain con l'elaborazione di parametri semiquantitativi non è immediata come il metodo di osservazione visiva, ma sembra fornire dati più oggettivi e sembra più appropriata per monitorare l'evoluzione della malattia. Tuttavia, affinché il metodo elastografico possa avere un ruolo più diffuso nelle malattie infiammatorie dell'intestino, sono necessari la standardizzazione del metodo e ulteriori studi che confermino i risultati promettenti già riportati in letteratura.
We face the factor analysis problem using a particular class of auto-regressive processes. We propose an approximate moment matching approach to estimate the number of factors as well as the parameters of the model. This algorithm alternates a step of factor analysis and a step of AR dynamics estimation. Some simulation studies show the effectiveness of the proposed estimator.
This paper deals with the dynamic factor analysis problem for an ARMA process. To robustly estimate the number of factors, we construct a confidence region centered in a finite sample estimate of the underlying model which contains the true model with a prescribed probability. In this confidence region, the problem, formulated as a rank minimization of a suitable spectral density, is efficiently approximated via a trace norm convex relaxation. The latter is addressed by resorting to the Lagrange duality theory, which allows to prove the existence of solutions. Finally, a numerical algorithm to solve the dual problem is presented. The effectiveness of the proposed estimator is assessed through simulation studies both with synthetic and real data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.