Transductive Transfer Learning for Domain Adaptation in Brain Magnetic Resonance Image Segmentation

Cervell; Imatge per ressonància magnètica; Aprenentatge transductiuCerebro; Imagen de resonancia magnética; Aprendizaje transductivoBrain; Magnetic resonance imaging; Transductive learningSegmentation of brain images from Magnetic Resonance Images (MRI) is an indispensable step in clinical practice. Morphological changes of sub-cortical brain structures and quantification of brain lesions are considered biomarkers of neurological and neurodegenerative disorders and used for diagnosis, treatment planning, and monitoring disease progression. In recent years, deep learning methods showed an outstanding performance in medical image segmentation. However, these methods suffer from generalisability problem due to inter-centre and inter-scanner variabilities of the MRI images. The main objective of the study is to develop an automated deep learning segmentation approach that is accurate and robust to the variabilities in scanner and acquisition protocols. In this paper, we propose a transductive transfer learning approach for domain adaptation to reduce the domain-shift effect in brain MRI segmentation. The transductive scenario assumes that there are sets of images from two different domains: (1) source—images with manually annotated labels; and (2) target—images without expert annotations. Then, the network is jointly optimised integrating both source and target images into the transductive training process to segment the regions of interest and to minimise the domain-shift effect. We proposed to use a histogram loss in the feature level to carry out the latter optimisation problem. In order to demonstrate the benefit of the proposed approach, the method has been tested in two different brain MRI image segmentation problems using multi-centre and multi-scanner databases for: (1) sub-cortical brain structure segmentation; and (2) white matter hyperintensities segmentation. The experiments showed that the segmentation performance of a pre-trained model could be significantly improved by up to 10%. For the first segmentation problem it was possible to achieve a maximum improvement from 0.680 to 0.799 in average Dice Similarity Coefficient (DSC) metric and for the second problem the average DSC improved from 0.504 to 0.602. Moreover, the improvements after domain adaptation were on par or showed better performance compared to the commonly used traditional unsupervised segmentation methods (FIRST and LST), also achieving faster execution time. Taking this into account, this work presents one more step toward the practical implementation of deep learning algorithms into the clinical routine.KK holds FI-DGR2017 grant from the Catalan Government with reference number 2017FI_B00372. This work has been supported by DPI2017-86696-R from the Ministerio de Ciencia y Tecnologia

Evaluating the use of synthetic T1-w images in new T2 lesion detection in multiple sclerosis

MRI; Deep learning; Multiple sclerosisResonancia magnética; Aprendizaje profundo; Esclerosis múltipleRessonància magnètica; Aprenentatge profund; Esclerosi múltipleThe assessment of disease activity using serial brain MRI scans is one of the most valuable strategies for monitoring treatment response in patients with multiple sclerosis (MS) receiving disease-modifying treatments. Recently, several deep learning approaches have been proposed to improve this analysis, obtaining a good trade-off between sensitivity and specificity, especially when using T1-w and T2-FLAIR images as inputs. However, the need to acquire two different types of images is time-consuming, costly and not always available in clinical practice. In this paper, we investigate an approach to generate synthetic T1-w images from T2-FLAIR images and subsequently analyse the impact of using original and synthetic T1-w images on the performance of a state-of-the-art approach for longitudinal MS lesion detection. We evaluate our approach on a dataset containing 136 images from MS patients, and 73 images with lesion activity (the appearance of new T2 lesions in follow-up scans). To evaluate the synthesis of the images, we analyse the structural similarity index metric and the median absolute error and obtain consistent results. To study the impact of synthetic T1-w images, we evaluate the performance of the new lesion detection approach when using (1) both T2-FLAIR and T1-w original images, (2) only T2-FLAIR images, and (3) both T2-FLAIR and synthetic T1-w images. Sensitivities of 0.75, 0.63, and 0.81, respectively, were obtained at the same false-positive rate (0.14) for all experiments. In addition, we also present the results obtained when using the data from the international MSSEG-2 challenge, showing also an improvement when including synthetic T1-w images. In conclusion, we show that the use of synthetic images can support the lack of data or even be used instead of the original image to homogenize the contrast of the different acquisitions in new T2 lesions detection algorithms.AC holds an FPI grant from the Ministerio de Ciencia, Innovación y Universidades with reference number PRE2018-083507. This work has been supported by DPI2020-114769RB-I00 from the Ministerio de Ciencia, Innovación y Universidades. The authors gratefully acknowledge the support of the NVIDIA Corporation with their donation of the TITAN X GPU used in this research. This work has been also supported by ICREA Academia Program

Ultrassonografia cardíaca en individus adietes a l'heroína intravenosa assimptomàtics: evidencia de lesions valvulars induïdes per l'adicció

Echocardiograph

Raman spectroscopy of self-catalyzed GaAs1-xSbx nanowires grown on silicon

Thanks to their wide band structure tunability, GaAs1-xSbx nanowires provide exciting perspectives in optoelectronic and energy harvesting applications. The control of composition and strain of these ternary alloys is crucial in the determination of their optical and electronic properties. Raman scattering provides information on the vibrational properties of materials, which can be related to the composition and strain. We present a systematic study of the vibrational properties of GaAs1-xSbx nanowires for Sb contents from 0 to 44%, as determined by energy-dispersive x-ray analyses. We find that optical phonons red-shift with increasing Sb content. We explain the shift by alloying effects, including mass disorder, dielectric changes and ionic plasmon coupling. The influence of Sb on the surface optical modes is addressed. Finally, we compare the luminescence yield between GaAs and GaAs1-xSbx, which can be related to a lower surface recombination rate. This work provides a reference for the study of ternary alloys in the form of nanowires, and demonstrates the tunability and high material quality of gold-free ternary antimonide nanowires directly grown on silicon

Representativeness in randomised clinical trials supporting acute coronary syndrome guidelines.

This project has received funding to cover the electronic case report form from the Balearic Society of Cardiology (Sociedad Balear Cardiología) through the ‘Bernat Nadal Ginard’ grant. Open access has been partly granted by the LIBERI PROGRAM 2023 of the Health Research Institute of the Balearic Islands (IdISBa).AIMS Clinical practice guidelines (CPGs) are published to guide the management of acute coronary syndrome (ACS). We aimed to critically appraise the representativeness and standard of care of randomised clinical trials (RCTs) supporting CPGs for ACS. METHODS AND RESULTS American and European CPGs for ST- and non-ST-elevation ACS were screened to extract all references (n = 2128) and recommendations (n = 600). Among the 407 primary publications of RCTs (19.1%), there were 52.6% and 73.2% recruiting patients in North America and Europe, respectively, whereas other regions were largely underrepresented (e.g., 25.3% RCTs recruited in Asia). There was 68.6% RCTs enrolling patient with ACS, whereas the remaining 31.4% did not enroll any patient with ACS. There was underrepresentation of some important subgroups, including elderly, female (29.9%) and non-white patients (<20%). The incidence and type of reperfusion reported in these RCTs were not reflective of current clinical practice (the percentage of patients who underwent percutaneous coronary intervention (PCI) among all RCTs was 42.7%; whereas for ST-Elevation Myocardial Infarction patients, the number of participants who underwent fibrinolysis was 3.3-fold higher than those who underwent primary PCI). All-cause mortality in these RCTs was 11.9% in RCTs with a follow-up ≤1 year. CONCLUSION RCTs supporting CPGs for ACS are not fully representative of the diversity of the ACS population and their current standard of care. While some of these issues with representativeness may be explained by how evidence has been accrued over time, efforts should be made by trialists to ensure that the evidence supporting CPGs is representative of the wider ACS population.S

Antifungal prophylaxis with nebulized amphotericin-B in solid-organ transplant recipients with severe COVID-19: a retrospective observational study

Aspergillosis; COVID-19; ProphylaxisAspergilosis; COVID-19; ProfilaxisAspergilosi; COVID 19; ProfilaxiCOVID-19-associated pulmonary aspergillosis (CAPA) has emerged as a frequent complication in the intensive care unit (ICU). However, little is known about this life-threatening fungal superinfection in solid organ transplant recipients (SOTRs), including whether targeted anti-mold prophylaxis might be justified in this immunosuppressed population. We performed a multicentric observational retrospective study of all consecutive ICU-admitted COVID-19 SOTRs between August 1, 2020 and December 31, 2021. SOTRs receiving antifungal prophylaxis with nebulized amphotericin-B were compared with those without prophylaxis. CAPA was defined according the ECMM/ISHAM criteria. Sixty-four SOTRs were admitted to ICU for COVID-19 during the study period. One patient received antifungal prophylaxis with isavuconazole and was excluded from the analysis. Of the remaining 63 SOTRs, nineteen (30.2%) received anti-mold prophylaxis with nebulized amphotericin-B. Ten SOTRs who did not receive prophylaxis developed pulmonary mold infections (nine CAPA and one mucormycosis) compared with one who received nebulized amphotericin-B (22.7% vs 5.3%; risk ratio 0.23; 95%CI 0.032-1.68), but with no differences in survival. No severe adverse events related to nebulized amphotericin-B were recorded. SOTRs admitted to ICU with COVID-19 are at high risk for CAPA. However, nebulized amphotericin-B is safe and might reduce the incidence of CAPA in this high-risk population. A randomized clinical trial to confirm these findings is warranted.AR received a predoctoral research grant from the Instituto de Salud Carlos III, Spanish Ministry of Science, Innovation and Universities, (PFIS grant FI18/00183). This work was supported by the Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Madrid, Spain. We thank CERCA Programme/Generalitat de Catalunya for institutional support

Myocardial remodelling and tissue characterisation by cardiovascular magnetic resonance (CMR) in endurance athletes

Our purpose was to evaluate by cardiovascular magnetic resonance (CMR) the presence of diffuse as well as focal MF in a series of high-performance veteran endurance athletes. Thirty-four veteran healthy male endurance athletes, still being in regular training, with more than 10 years of training underwent a CMR. A cardiopulmonary exercise test was also performed to assess their maximal physical performance. The control group consisted in 12 non-trained normal individuals. We found an increase in both, right and left ventricular (LV) volumes in the athlete's group when compared with controls. There was no increase in indexed LV myocardial mass despite of a significantly increased maximal myocardial wall thickness in comparison to controls. Native T1 values and extracellular volume (ECV) were normal in all cases. We did not find differences in native T1 values and ECV between both groups. In three athletes (9%), non-ischaemic late gadolinium enhancement (LGE) was observed. We did not find a correlation between total training volume and presence of LGE or with the ECV value. Our results show that the majority of veteran endurance athletes present with myocardial remodelling without MF as a physiological adaptive phenomenon. In the only three athletes with focal MF, the LGE pattern observed suggests an intercurrent event not related with the remodelling phenomenon