1,721,259 research outputs found
Artificial intelligence propels lung cancer screening: innovations and the challenges of explainability and reproducibility
Full text link[Cavernous angiomatosis of the central nervous system starting in the medulla. A case report]. FT Angiomatosi cavernosa del sistema nervoso centrale ad esordio midollare. Un caso.
No full textCharacterization of Nyquist ghost in EPI-fMRI acquisition sequences implemented on two clinical 1.5 T MR scanner systems: effect of readout bandwidth and echo spacing
No full textIn EPI-fMRI acquisitions, various readout bandwidth (BW) values are used as a function of gradients' characteristics of the MR scanner system. Echo spacing (ES) is another fundamental parameter of EPI-fMRI sequences, but the employed ES value is not usually reported in fMRI studies. Nyquist ghost is a typical EPI artifact that can degrade the overall quality of fMRI time series. In this work, the authors assessed the basic effect of BW and ES for two clinical 1.5 T MR scanner systems (scanner-A, scanner-B) on Nyquist ghost of gradient-echo EPI-fMRI sequences. BW range was: scanner-A, 1953-3906 Hz/pixel; scanner-B, 1220-2894 Hz/pixel. ES range was: scanner-A, scanner-B: 0.75-1.33 ms. The ghost-to-signal ratio of time series acquisition (GSRts) and drift of ghost-to-signal ratio (DRGSR) were measured in a water phantom. For both scanner-A (93% of variation) and scanner-B (102% of variation) the mean GSRts significantly increased with increasing BW. GSRts values of scanner-A did not significantly depended on ES. On the other hand, GSRts values of scanner-B significantly varied with ES, showing a downward trend (81% of variation) with increasing ES. In addition, a GSRts spike point at ES = 1.05 ms indicating a potential resonant effect was revealed. For both scanners, no significant effect of ES on DRGSR was revealed. DRGSR values of scanner-B did not significantly vary with BW, whereas DRGSR values of scanner-A significantly depended on BW showing an upward trend from negative to positive values with increasing BW. GSRts and DRGSR can significantly vary with BW and ES, and the specific pattern of variation may depend on gradients performances, EPI sequence calibrations and functional design of radiofrequency coil. Thus, each MR scanner system should be separately characterized. In general, the employment of low BW values seems to reduce the intensity and temporal variation of Nyquist ghost in EPI-fMRI time series. On the other hand, the use of minimum ES value might not be entirely advantageous when the MR scanner is characterized by gradients with low performances and suboptimal EPI sequence calibration
The Pivotal Role of Baseline LDCT for Lung Cancer Screening in the Era of Artificial Intelligence
Full text linkIn this narrative review, we address the ongoing challenges of lung cancer (LC) screening using chest low-dose computerized tomography (LDCT) and explore the contributions of artificial intelligence (AI), in overcoming them. We focus on evaluating the initial (baseline) LDCT examination, which provides a wealth of information relevant to the screening participant's health. This includes the detection of large-size prevalent LC and small-size malignant nodules that are typically diagnosed as LCs upon growth in subsequent annual LDCT scans. Additionally, the baseline LDCT examination provides valuable information about smoking-related comorbidities, including cardiovascular disease, chronic obstructive pulmonary disease, and interstitial lung disease (ILD), by identifying relevant markers. Notably, these comorbidities, despite the slow progression of their markers, collectively exceed LC as ultimate causes of death at follow-up in LC screening participants. Computer-assisted diagnosis tools currently improve the reproducibility of radiologic readings and reduce the false negative rate of LDCT. Deep learning (DL) tools that analyze the radiomic features of lung nodules are being developed to distinguish between benign and malignant nodules. Furthermore, AI tools can predict the risk of LC in the years following a baseline LDCT. AI tools that analyze baseline LDCT examinations can also compute the risk of cardiovascular disease or death, paving the way for personalized screening interventions. Additionally, DL tools are available for assessing osteoporosis and ILD, which helps refine the individual's current and future health profile. The primary obstacles to AI integration into the LDCT screening pathway are the generalizability of performance and the explainability
La tecnologia laser nella pulitura dei manufatti lapidei, casi studio a confronto
No full textIn questo lavoro viene presentata la sperimentazione condotta, nell’ambito di una tesi di Laurea Magistrale a Ciclo Unico in Conservazione e Restauro dei Beni Culturali, presso l’Istituto di Fisica Applicata “Nello Carrara” del Consiglio Nazionale delle Ricerche di Firenze, per valutate le potenzialità di diversi regimi laser Nd:YAG a 1064 nm: Short Free Running (30 - 110 μs) e Long Q-Switch a singolo, doppio e triplo impulso (120 ns distanziati tra loro da 40 μs).
A tale scopo sono stati selezionati alcuni frammenti di manufatti lapidei, di diverso periodo storico, databili tra il XVII secolo a.C. e il XX secolo, che offrivano problematiche conservative di particolare interesse.
La conoscenza di questi manufatti e delle fenomenologie di degrado presenti su di essi è stata approfondita attraverso l’impiego sinergico di diverse tecniche di indagine, a partire da quelle non distruttive, quali la Microscopia Raman, Riflettenza Vis-NIR e Misure Colorimetriche. Successivamente, sono stati condotti il prelievo e l’analisi di micro-campioni, studiati con l’ausilio della Microscopia Ottica, in luce visibile e fluorescenza, Microscopia Elettronica a Scansione (SEM) e Microanalisi chimica elementare EDS (Spettrometria RX a dispersione di energia).
Sui manufatti selezionati sono state condotte delle prove di ablazione laser, utilizzando diverse modalità operative, al fine di individuare le soglie di danno e gli intervalli operativi di fluenza idonei e ponendo particolare attenzione alla valutazione l’efficienza del processo di pulitura.
Gli effetti dell’irraggiamento e i diversi livelli di pulitura ottenibili sono stati valutati approfonditamente anche grazie all’ausilio di confronti colorimetrici e la realizzazione di cross section, osservate e analizzate tramite Microscopia Ottica ed Elettronica.
Variando opportunamente le condizioni operative è stato possibile ottenere dei livelli di pulitura ottimali, nel rispetto delle complessità delle differenti superfici trattate, e vagliare tutte le possibili implicazioni dell’uso di un regime o di un altro, al fine di attuare un corretto, puntuale e selettivo intervento conservativo, specifico per i casi studio esaminati.
I risultati ottenuti confermano le innumerevoli potenzialità di questa tecnica, il cui impiego è ormai consolidato nel settore del restauro, ma soprattutto evidenziano l’estrema importanza di disporre di diversi regimi di funzionamento, vista la grande variabilità delle condizioni operative ottimali in funzione della tipologia di degrado e di manufatto trattati
Misleading imaging features of intracranial dural plasmacytoma: Report of two cases
No full textDurai plasmacytomas are very rare and often disregarded in the differential diagnosis of more common lesions of the convexity. We report two cases. Both patients exhibited headache as a main symptom. Computed tomography and magnetic resonance showed a homogeneously enhanced lesion without calcification and without bone involvement
Automated segmentation refinement of small lung nodules in CT scans by local shape analysis
No full textOne of the most important problems in the segmentation of lung nodules in CT imaging arises from possible attachments occurring between nodules and other lung structures, such as vessels or pleura. In this report, we address the problem of vessels attachments by proposing an automated correction method applied to an initial rough segmentation of the lung nodule. The method is based on a local shape analysis of the initial segmentation making use of 3-D geodesic distance map representations. The correction method has the advantage that it locally refines the nodule segmentation along recognized vessel attachments only, without modifying the nodule boundary elsewhere. The method was tested using a simple initial rough segmentation, obtained by a fixed image thresholding. The validation of the complete segmentation algorithm was carried out on small lung nodules, identified in the ITALUNG screening trial and on small nodules of the lung image database consortium (LIDC) dataset. In fully automated mode, 217/256 (84.8%) lung nodules of ITALUNG and 139/157 (88.5%) individual marks of lung nodules of LIDC were correctly outlined and an excellent reproducibility was also observed. By using an additional interactive mode, based on a controlled manual interaction, 233/256 (91.0%) lung nodules of ITALUNG and 144/157 (91.7%) individual marks of lung nodules of LIDC were overall correctly segmented. The proposed correction method could also be usefully applied to any existent nodule segmentation algorithm for improving the segmentation quality of juxta-vascular nodules
Toward a more reliable characterization of fractal properties of the cerebral cortex of healthy subjects during the lifespan
Full text linkThe cerebral cortex manifests an inherent structural complexity of folding. The fractal geometry describes the complexity of structures which show self-similarity in a proper interval of spatial scales. In this study, we aimed at evaluating in-vivo the effect of different criteria for selecting the interval of spatial scales in the estimation of the fractal dimension (FD) of the cerebral cortex in T1-weighted magnetic resonance imaging (MRI). We compared four different strategies, including two a priori selections of the interval of spatial scales, an automated selection of the spatial scales within which the cerebral cortex manifests the highest statistical self-similarity, and an improved approach, based on the search of the interval of spatial scales which presents the highest rounded R2adj coefficient and, in case of equal rounded R2adj coefficient, preferring the widest interval in the log–log plot. We employed two public and international datasets of in-vivo MRI scans for a total of 159 healthy subjects (age range 6–85 years). The improved approach showed strong associations of FD with age and yielded the most accurate machine learning models for individual age prediction in both datasets. Our results indicate that the selection of the interval of spatial scales of the cerebral cortex is thus critical in the estimation of FD
Gender effect in the ITALUNG screening trial. A comparison with UKLS and other trials
Full text linkThe existence of gender differences in the efficacy of
lung cancer (LC) screening with low dose CT is an inter-
esting issue. In the meta-analysis associated with the
mortality results of the UKLS trial, larger reductions of
LC mortality were observed in females in the NELSON,
NLST and LUSI trials, but not in the UKLS. 1 ITALUNG
trial is a small size study that recruited 1132 women and
2074 men who were younger and predominantly cur-
rent smokers as compared to those in UKLS, 2 and
reported a 30% reduction of LC mortality in the active
group. 3 After a follow-up extension of two years, the
decreased LC mortality was 24%. 4 Herein we report
gender effect in the ITALUNG extended follow-up data-
set. Females showed a more pronounced LC mortality
reduction (10 LC deaths during 6419 person-years in
the active group and 16 LC deaths during 6076 person-
years in the control group, resulting in a rate ratio of
0.59; 95%CI:0.27-1.30) than males (48 LC deaths dur-
ing 11168 person-years in the active group and 58 LC
deaths during 10975 person-years in the control group,
resulting in a rate ratio of 0.81; 95%CI:0.56-1.19). The
more pronounced benefit of LC screening in women
was non statistically significant (p=0.477). Reasons
underlying the greater LC reduction in females partici-
pating to LC screening are unclear. Women have LC
with a longer preclinical sojourn time, especially in case
of adenocarcinoma, that would favour the possibility of
screening detection. 5 Women might also be in healthier
general conditions and have less co-morbidities
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