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BACKGROUND: Ocular siderosis (OS) is a significant cause of visual loss due to retained ferrous intraocular foreign bodies (IOFB). Despite its rarity, OS can lead to severe visual impairment if not promptly diagnosed and treated. This case is notable due to the occult nature of the IOFB, which was undetected by standard imaging modalities, emphasizing the critical role of magnetic resonance imaging (MRI) in such scenarios. CASE PRESENTATION: A 51-year-old Caucasian male presented with progressive vision loss in his right eye over 20 days. Best corrected visual acuity (BCVA) was 20/1000 in the right eye and 20/20 in the left eye. Intraocular pressure (IOP) was 9 mmHg in both eyes. Slit-lamp examination revealed a small linear corneal wound and an iris defect in the right eye, along with a cataract featuring brownish deposits on the anterior capsule. The left eye was normal. Fundus examination of the right eye was hindered by media opacities. Ultrasonography showed a flat retina and choroid with no detectable IOFB. Despite a strong clinical suspicion of OS, computed tomography (CT) did not detect any IOFB. MRI subsequently identified an artifact in the inferior sectors of the right eye, indicative of a metallic IOFB. Surgical intervention involved a 23-gauge vitrectomy, phacoemulsification, IOFB removal and silicon oil (SO) tamponade resulting in a fully restored VA of 20/20 and normal IOP one month post-operation. SO was removed 2 months later. The retina remained adherent with no PVR development, and optical coherence tomography (OCT) scans showed a normal macula. CONCLUSIONS: This case underscores the importance of considering OS in patients with unexplained vision loss and history of ocular trauma, even when initial imaging fails to detect an IOFB. MRI proved crucial in identifying the IOFB, highlighting its value in the diagnostic process. Early detection and surgical removal of IOFBs are essential to prevent irreversible visual damage. This case demonstrates that MRI should be employed when CT and ultrasonography are inconclusive, ensuring accurate diagnosis and timely intervention to preserve vision.
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Cuerpos Extraños en el Ojo , Lesiones Oculares Penetrantes , Imagen por Resonancia Magnética , Siderosis , Humanos , Cuerpos Extraños en el Ojo/diagnóstico , Cuerpos Extraños en el Ojo/cirugía , Masculino , Persona de Mediana Edad , Lesiones Oculares Penetrantes/diagnóstico , Lesiones Oculares Penetrantes/cirugía , Siderosis/diagnóstico , Agudeza Visual , VitrectomíaRESUMEN
BACKGROUND: The amygdala and the hippocampus are two limbic structures that play a critical role in cognition and behavior, however their manual segmentation and that of their smaller nuclei/subfields in multicenter datasets is time consuming and difficult due to the low contrast of standard MRI. Here, we assessed the reliability of the automated segmentation of amygdalar nuclei and hippocampal subfields across sites and vendors using FreeSurfer in two independent cohorts of older and younger healthy adults. METHODS: Sixty-five healthy older (cohort 1) and 68 younger subjects (cohort 2), from the PharmaCog and CoRR consortia, underwent repeated 3D-T1 MRI (interval 1-90 days). Segmentation was performed using FreeSurfer v6.0. Reliability was assessed using volume reproducibility error (ε) and spatial overlapping coefficient (DICE) between test and retest session. RESULTS: Significant MRI site and vendor effects (p â< â.05) were found in a few subfields/nuclei for the ε, while extensive effects were found for the DICE score of most subfields/nuclei. Reliability was strongly influenced by volume, as ε correlated negatively and DICE correlated positively with volume size of structures (absolute value of Spearman's r correlations >0.43, p â< â1.39E-36). In particular, volumes larger than 200 âmm3 (for amygdalar nuclei) and 300 âmm3 (for hippocampal subfields, except for molecular layer) had the best test-retest reproducibility (ε â< â5% and DICE â> â0.80). CONCLUSION: Our results support the use of volumetric measures of larger amygdalar nuclei and hippocampal subfields in multisite MRI studies. These measures could be useful for disease tracking and assessment of efficacy in drug trials.
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Amígdala del Cerebelo/anatomía & histología , Hipocampo/anatomía & histología , Procesamiento de Imagen Asistido por Computador/normas , Neuroimagen/normas , Programas Informáticos , Adulto , Anciano , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Imagen por Resonancia Magnética/normas , Masculino , Persona de Mediana Edad , Neuroimagen/métodos , Reproducibilidad de los ResultadosRESUMEN
PURPOSE: The aim of this study was to compare the diagnostic accuracy of magnetic resonance imaging (MRI) and dual-energy computed tomography (DECT) to identify residual-recurrent cholesteatoma using the second-look surgery as the reference standard. METHODS: This prospective, institutional review board-approved study included 19 consecutive patients (11 males and 8 females; mean age of 62.2, range 34-80 years). Since five patients were studied bilaterally, a total of 24 ears were evaluated with DECT and MRI between February 2017 and June 2018. Any abnormal middle ear attenuation on high-resolution CT images (HRCT) or DECT color-coded maps, and any abnormal signal on MRI images was evaluated by four experienced radiologists. Diagnostic accuracy values of HRCT, DECT maps and CT numbers (by using receiver operator curves) and MRI were compared. Interobserver and intraobserver agreement were calculated. RESULTS: Residual-recurrent cholesteatoma was diagnosed at surgery in 16/24 ears (66.6%). MRI and DECT revealed a total of 15/16 and 14/16 cholesteatomas, respectively. The sensitivity, specificity, PPV and NPV and accuracy of MRI and DECT were 93.7, 87.5, 93.7, 87.5, and 91.6% and 87.5, 87.5, 93.3, 87.5 and 87.5%, respectively. CT numbers were significantly different between positive (mean 57.6 HU, range - 65, 112 HU) and negative cases (mean 5.4 HU, range - 100, 66 HU) with p < 0.001. The interobserver and intraobserver agreement were k = 0.87 and k = 0.83, respectively. CONCLUSION: DECT may provide an accurate demonstration of residual-recurrent middle ear cholesteatoma.
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Colesteatoma del Oído Medio/diagnóstico por imagen , Colesteatoma del Oído Medio/patología , Imagen por Resonancia Magnética/métodos , Tomografía Computarizada por Rayos X/métodos , Adulto , Anciano , Anciano de 80 o más Años , Colesteatoma del Oído Medio/cirugía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Recurrencia , Segunda Cirugía , Sensibilidad y EspecificidadRESUMEN
PURPOSE: The aim of this study was to evaluate DECT diagnostic accuracy in the identification of vertebral bone marrow edema, using MRI as standard of reference. METHODS: This prospective institutional review board-approved study included 76 consecutive patients (29 males and 47 females; mean age 62.3, range 51-82 years) studied with DECT (90 kV and tin filter 150 kV) and MRI within 7 days. Three radiologists evaluated DECT (reader 1 and 2) and MRI images (reader 3). Diagnostic accuracy of the DECT maps (qualitative assessment) and of the CT numbers (quantitative assessment), interobserver and intraobserver agreements were calculated. RESULTS: MRI revealed 61 edematous vertebrae and 52 collapsed non-edematous vertebrae. The sensitivity, specificity, PPV and NPV and accuracy of the qualitative assessment of the DECT maps were 88.6, 92.3, 93.1, 87.3 and 90.3%, for reader 1, 90.2, 90.3, 91.6, 88.7 and 90.3, for reader 2, and 91.8, 90.4, 91.6, 90.4 and 91.1% for quantitative analysis, respectively. DECT numbers were significantly different between positive (mean - 23 HU, range - 189, 29 HU) and negative cases (mean - 126 HU, range - 321, - 66 HU) with p < 0.001. The ROC curve analysis revealed an AUC of 0.886 (95% confidence interval 0.722-0.913). The interobserver and intraobserver agreements were near perfect (k = 0.87 and k = 0.83, respectively). CONCLUSION: DECT represents an accurate imaging technique for demonstrating bone marrow edema in vertebral compression fracture, if compared to MRI.
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Enfermedades de la Médula Ósea/diagnóstico por imagen , Edema/diagnóstico por imagen , Fracturas por Compresión/diagnóstico por imagen , Fracturas de la Columna Vertebral/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Sensibilidad y EspecificidadRESUMEN
OBJECTIVE: To evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) to identify bone marrow edema (BME) of the ankle. METHODS: This prospective institutional review board approved study included 40 consecutive patients (29 males and 11 females; mean age of 32.3 years) studied with DECT (80 kV and tin filter 150 kV) and MRI within 10 days. DECT data were post-processed for generating non-calcium images of the ankle. Two radiologists evaluated the presence of BME on color-coded maps. Diagnostic accuracy values for diagnosing BME were calculated for DECT maps (qualitative assessment) and for CT numbers (quantitative assessment) by using receiver operator curves and area under the curve (AUC), using MRI as the gold standard. Interobserver and intraobserver agreements were calculated with k-statistics. A p < 0.05 was considered statistically significant. RESULTS: DECT depicted BME in 23/25 patients (92.0%). The sensitivity, specificity, PPV and NPV, and accuracy achieved by evaluating the DECT images were 92.0, 86.6, 92.0, 84.6, and 90.0%, for reader 1 and 88.0, 86.6, 91.6, 78.6, and 87.5, for reader 2, respectively. The interobserver and intraobsever agreements were near perfect (k = 0.87 and k = 0.83, respectively). DECT numbers were significantly different between positive (mean - 12.6 ± 29.6 HU) and negative cases (mean - 64.2 ± 34.5 HU) with a p value < 0.001. By using - 20HU cutoff to identify BME (AUC of 0.896.), the sensitivity, specificity, PPV and NPV, and accuracy of the quantitative analysis were 88.0, 92.6, 95.7, 92.6, and 87.5%, respectively. CONCLUSION: DECT represents an accurate imaging tool for demonstration of BME of the ankle when compared to MRI.
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Articulación del Tobillo/diagnóstico por imagen , Enfermedades de la Médula Ósea/diagnóstico por imagen , Edema/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Tomografía Computarizada por Rayos X/métodos , Adulto , Femenino , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Estudios Prospectivos , Sensibilidad y EspecificidadRESUMEN
Free water elimination (FWE) in brain diffusion MRI has been shown to improve tissue specificity in human white matter characterization both in health and in disease. Relative to the classical diffusion tensor imaging (DTI) model, FWE is also expected to increase sensitivity to microstructural changes in longitudinal studies. However, it is not clear if these two models differ in their test-retest reproducibility. This study compares a bi-tensor model for FWE with DTI by extending a previous longitudinal-reproducibility 3T multisite study (10 sites, 7 different scanner models) of 50 healthy elderly participants (55-80 years old) scanned in two sessions at least 1 week apart. We computed the reproducibility of commonly used DTI metrics (FA: fractional anisotropy, MD: mean diffusivity, RD: radial diffusivity, and AXD: axial diffusivity), derived either using a DTI model or a FWE model. The DTI metrics were evaluated over 48 white-matter regions of the JHU-ICBM-DTI-81 white-matter labels atlas, and reproducibility errors were assessed. We found that relative to the DTI model, FWE significantly reduced reproducibility errors in most areas tested. In particular, for the FA and MD metrics, there was an average reduction of approximately 1% in the reproducibility error. The reproducibility scores did not significantly differ across sites. This study shows that FWE improves sensitivity and is thus promising for clinical applications, with the potential to identify more subtle changes. The increased reproducibility allows for smaller sample size or shorter trials in studies evaluating biomarkers of disease progression or treatment effects. Hum Brain Mapp 38:12-26, 2017. © 2016 Wiley Periodicals, Inc.
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Envejecimiento , Encéfalo/diagnóstico por imagen , Imagen de Difusión Tensora , Agua/metabolismo , Anciano , Anciano de 80 o más Años , Anisotropía , Femenino , Voluntarios Sanos , Humanos , Imagenología Tridimensional , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sustancia Blanca/diagnóstico por imagenRESUMEN
To date, limited data are available regarding the inter-site consistency of test-retest reproducibility of functional connectivity measurements, in particular with regard to integrity of the Default Mode Network (DMN) in elderly participants. We implemented a harmonized resting-state fMRI protocol on 13 clinical scanners at 3.0T using vendor-provided sequences. Each site scanned a group of 5 healthy elderly participants twice, at least a week apart. We evaluated inter-site differences and test-retest reproducibility of both temporal signal-to-noise ratio (tSNR) and functional connectivity measurements derived from: i) seed-based analysis (SBA) with seed in the posterior cingulate cortex (PCC), ii) group independent component analysis (ICA) separately for each site (site ICA), and iii) consortium ICA, with group ICA across the whole consortium. Despite protocol harmonization, significant and quantitatively important inter-site differences remained in the tSNR of resting-state fMRI data; these were plausibly driven by hardware and pulse sequence differences across scanners which could not be harmonized. Nevertheless, the tSNR test-retest reproducibility in the consortium was high (ICC=0.81). The DMN was consistently extracted across all sites and analysis methods. While significant inter-site differences in connectivity scores were found, there were no differences in the associated test-retest error. Overall, ICA measurements were more reliable than PCC-SBA, with site ICA showing higher reproducibility than consortium ICA. Across the DMN nodes, the PCC yielded the most reliable measurements (≈4% test-retest error, ICC=0.85), the medial frontal cortex the least reliable (≈12%, ICC=0.82) and the lateral parietal cortices were in between (site ICA). Altogether these findings support usage of harmonized multisite studies of resting-state functional connectivity to characterize longitudinal effects in studies that assess disease progression and treatment response.
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Mapeo Encefálico/métodos , Encéfalo/fisiología , Giro del Cíngulo/fisiología , Imagen por Resonancia Magnética/métodos , Anciano , Anciano de 80 o más Años , Artefactos , Interpretación Estadística de Datos , Humanos , Estudios Longitudinales , Persona de Mediana Edad , Vías Nerviosas/fisiología , Reproducibilidad de los Resultados , Relación Señal-RuidoRESUMEN
Understanding how to reduce the influence of physiological noise in resting state fMRI data is important for the interpretation of functional brain connectivity. Limited data is currently available to assess the performance of physiological noise correction techniques, in particular when evaluating longitudinal changes in the default mode network (DMN) of healthy elderly participants. In this 3T harmonized multisite fMRI study, we investigated how different retrospective physiological noise correction (rPNC) methods influence the within-site test-retest reliability and the across-site reproducibility consistency of DMN-derived measurements across 13 MRI sites. Elderly participants were scanned twice at least a week apart (five participants per site). The rPNC methods were: none (NPC), Tissue-based regression, PESTICA and FSL-FIX. The DMN at the single subject level was robustly identified using ICA methods in all rPNC conditions. The methods significantly affected the mean z-scores and, albeit less markedly, the cluster-size in the DMN; in particular, FSL-FIX tended to increase the DMN z-scores compared to others. Within-site test-retest reliability was consistent across sites, with no differences across rPNC methods. The absolute percent errors were in the range of 5-11% for DMN z-scores and cluster-size reliability. DMN pattern overlap was in the range 60-65%. In particular, no rPNC method showed a significant reliability improvement relative to NPC. However, FSL-FIX and Tissue-based physiological correction methods showed both similar and significant improvements of reproducibility consistency across the consortium (ICC = 0.67) for the DMN z-scores relative to NPC. Overall these findings support the use of rPNC methods like tissue-based or FSL-FIX to characterize multisite longitudinal changes of intrinsic functional connectivity. Hum Brain Mapp 37:2114-2132, 2016. © 2016 Wiley Periodicals, Inc.
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Mapeo Encefálico , Encéfalo/fisiología , Imagen por Resonancia Magnética , Anciano , Mapeo Encefálico/métodos , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Vías Nerviosas/fisiología , Análisis de Regresión , Reproducibilidad de los Resultados , Descanso , Estudios RetrospectivosRESUMEN
Recently, there has been an increased interest in the use of automatically segmented subfields of the human hippocampal formation derived from magnetic resonance imaging (MRI). However, little is known about the test-retest reproducibility of such measures, particularly in the context of multisite studies. Here, we report the reproducibility of automated Freesurfer hippocampal subfields segmentations in 65 healthy elderly enrolled in a consortium of 13 3T MRI sites (five subjects per site). Participants were scanned in two sessions (test and retest) at least one week apart. Each session included two anatomical 3D T1 MRI acquisitions harmonized in the consortium. We evaluated the test-retest reproducibility of subfields segmentation (i) to assess the effects of averaging two within-session T1 images and (ii) to compare subfields with whole hippocampus volume and spatial reliability. We found that within-session averaging of two T1 images significantly improved the reproducibility of all hippocampal subfields but not that of the whole hippocampus. Volumetric and spatial reproducibility across MRI sites were very good for the whole hippocampus, CA2-3, CA4-dentate gyrus (DG), subiculum (reproducibility errorâ¼2% and DICE > 0.90), good for CA1 and presubiculum (reproducibility error â¼ 5% and DICE â¼ 0.90), and poorer for fimbria and hippocampal fissure (reproducibility error â¼ 15% and DICE < 0.80). Spearman's correlations confirmed that test-retest reproducibility improved with volume size. Despite considerable differences of MRI scanner configurations, we found consistent hippocampal subfields volumes estimation. CA2-3, CA4-DG, and sub-CA1 (subiculum, presubiculum, and CA1 pooled together) gave test-retest reproducibility similar to the whole hippocampus. Our findings suggest that the larger hippocampal subfields volume may be reliable longitudinal markers in multisite studies.
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Envejecimiento/patología , Hipocampo/anatomía & histología , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Reconocimiento de Normas Patrones Automatizadas/métodos , Anciano , Europa (Continente) , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Tamaño de los Órganos , Reproducibilidad de los Resultados , Programas InformáticosRESUMEN
Large-scale longitudinal neuroimaging studies with diffusion imaging techniques are necessary to test and validate models of white matter neurophysiological processes that change in time, both in healthy and diseased brains. The predictive power of such longitudinal models will always be limited by the reproducibility of repeated measures acquired during different sessions. At present, there is limited quantitative knowledge about the across-session reproducibility of standard diffusion metrics in 3T multi-centric studies on subjects in stable conditions, in particular when using tract based spatial statistics and with elderly people. In this study we implemented a multi-site brain diffusion protocol in 10 clinical 3T MRI sites distributed across 4 countries in Europe (Italy, Germany, France and Greece) using vendor provided sequences from Siemens (Allegra, Trio Tim, Verio, Skyra, Biograph mMR), Philips (Achieva) and GE (HDxt) scanners. We acquired DTI data (2 × 2 × 2 mm(3), b = 700 s/mm(2), 5 b0 and 30 diffusion weighted volumes) of a group of healthy stable elderly subjects (5 subjects per site) in two separate sessions at least a week apart. For each subject and session four scalar diffusion metrics were considered: fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial (AD) diffusivity. The diffusion metrics from multiple subjects and sessions at each site were aligned to their common white matter skeleton using tract-based spatial statistics. The reproducibility at each MRI site was examined by looking at group averages of absolute changes relative to the mean (%) on various parameters: i) reproducibility of the signal-to-noise ratio (SNR) of the b0 images in centrum semiovale, ii) full brain test-retest differences of the diffusion metric maps on the white matter skeleton, iii) reproducibility of the diffusion metrics on atlas-based white matter ROIs on the white matter skeleton. Despite the differences of MRI scanner configurations across sites (vendors, models, RF coils and acquisition sequences) we found good and consistent test-retest reproducibility. White matter b0 SNR reproducibility was on average 7 ± 1% with no significant MRI site effects. Whole brain analysis resulted in no significant test-retest differences at any of the sites with any of the DTI metrics. The atlas-based ROI analysis showed that the mean reproducibility errors largely remained in the 2-4% range for FA and AD and 2-6% for MD and RD, averaged across ROIs. Our results show reproducibility values comparable to those reported in studies using a smaller number of MRI scanners, slightly different DTI protocols and mostly younger populations. We therefore show that the acquisition and analysis protocols used are appropriate for multi-site experimental scenarios.
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Imagen de Difusión Tensora/normas , Sustancia Blanca/anatomía & histología , Anciano , Anciano de 80 o más Años , Imagen de Difusión Tensora/instrumentación , Imagen de Difusión Tensora/métodos , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Reproducibilidad de los ResultadosRESUMEN
PURPOSE: To assess the applicability of arterial spin labeling (ASL) in comparison to blood-oxygenation-level-dependent (BOLD) contrast fMRI in detecting brain activations elicited by active and passive hand movements. MATERIALS AND METHODS: A block design for ASL and BOLD fMRI was applied in 8 healthy subjects using active and passive hand tasks. Data analyses were performed at individual and group level, comparing both the different movements and the performance of the two techniques. RESULTS: Group analyses showed involvement of the same areas during both tasks, as the contralateral sensorimotor cortex, supplementary motor area, cerebellum, inferior parietal lobes, thalamus. ASL detected smaller activation volumes than BOLD, but the areas had a high degree of colocalization. Few significant differences (P < 0.05) were found when the two tasks were compared for the number of activated voxels, coordinates of center of mass, and CBF estimates. Considering together all the areas, the mean %BOLD change was 0.79 ± 0.27 and 0.73 ± 0.24 for the active and passive movements respectively, while the mean %CBF changes were 34.1 ± 8.9 and 27.1 ± 14.8. CONCLUSION: Our findings confirm passive and active tasks are strongly coupled, supporting the importance of passive tasks as a diagnostic tool in the clinical setting. ASL fMRI proved suitable for functional mapping and quantifying CBF changes, making it a promising technique for patient cohort applications.
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Velocidad del Flujo Sanguíneo/fisiología , Mapeo Encefálico/métodos , Encéfalo/fisiología , Circulación Cerebrovascular/fisiología , Interpretación de Imagen Asistida por Computador/métodos , Angiografía por Resonancia Magnética/métodos , Movimiento/fisiología , Adulto , Encéfalo/irrigación sanguínea , Femenino , Humanos , Aumento de la Imagen/métodos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Marcadores de SpinRESUMEN
BACKGROUND: Psoriasis is frequently associated with cardiometabolic comorbidities and depression that are risk factors for cognitive impairment. OBJECTIVE: To investigate cognitive performance in psoriatic patients. METHOD: Cognitive performances were assessed by neuropsychological tests in 41 patients with psoriasis and 37 controls. Diagnostic criteria for mild cognitive impairment (MCI) were (1) subjective complaint of a memory deficit, confirmed by a relative or caregiver, (2) pathological performance on neuropsychological tests investigating cognitive domains, (3) normal performance of daily living activities and (4) no dementia. Neuroimaging was studied by high-field magnetic resonance imaging and cortical thickness analysis. RESULTS: MCI was found in 18 out of 41 (44%) patients with psoriasis compared to 4 out of 37 (11%) controls (p = 0.002). In particular, patients with psoriasis had lower scores in the delayed recall of the Rey Auditory Verbal Learning Test (p = 0.04), Backwards Digit Span Test (p = 0.002), Weigl's Sorting Test (p = 0.01) and Trail Making Test B (p = 0.008). In the 7 patients submitted to cortical thickness analysis, a reduction in brain thickness in parahippocampal, superior temporal and frontal gyri of the left hemisphere was observed. CONCLUSIONS: Patients with psoriasis may have a precocious impairment of long-term verbal memory, executive functions and attention.
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Encéfalo/patología , Disfunción Cognitiva/etiología , Psoriasis/psicología , Anciano , Estudios de Casos y Controles , Enfermedad Crónica , Estudios Transversales , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Memoria a Largo Plazo , Persona de Mediana Edad , Neuroimagen , Índice de Severidad de la Enfermedad , Prueba de Secuencia AlfanuméricaRESUMEN
OBJECTIVE: Among other neuroimaging techniques, functional magnetic resonance imaging (fMRI) can be useful for studying the development of motor fatigue. The aim of this study was to identify differences in cortical neuronal activation in nine subjects on three motor tasks: right-hand movement with minimum, maximum, and post-fatigue maximum finger flexion. MATERIALS AND METHODS: fMRI activation maps for each subject and during each condition were obtained by estimating the optimal model of the hemodynamic response function (HRF) out of four standard HRF models and an individual-based HRF model (ibHRF). RESULTS: ibHRF was selected as the optimal model in six out of nine subjects for minimum movement, in five out of nine for maximum movement, and in eight out of nine for post-fatigue maximum movement. As compared to maximum movement, a large reduction in the total number of active voxels (primary sensorimotor area, supplementary motor area and cerebellum) was observed in post-fatigue maximum movement. CONCLUSION: This is the first approach to the evaluation of long-lasting contraction effort in healthy subjects by means of the fMRI paradigm with the use of an individual-based hemodynamic response. The results may be relevant for defining a baseline in future studies on central fatigue in patients with neuropathological disorders.
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Potenciales Evocados Motores/fisiología , Imagen por Resonancia Magnética/métodos , Corteza Motora/fisiología , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Consumo de Oxígeno/fisiología , Resistencia Física/fisiología , Adulto , Mapeo Encefálico/métodos , Femenino , Humanos , Masculino , Esfuerzo Físico/fisiología , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Volición/fisiología , Adulto JovenRESUMEN
Large-scale longitudinal multi-site MRI brain morphometry studies are becoming increasingly crucial to characterize both normal and clinical population groups using fully automated segmentation tools. The test-retest reproducibility of morphometry data acquired across multiple scanning sessions, and for different MR vendors, is an important reliability indicator since it defines the sensitivity of a protocol to detect longitudinal effects in a consortium. There is very limited knowledge about how across-session reliability of morphometry estimates might be affected by different 3T MRI systems. Moreover, there is a need for optimal acquisition and analysis protocols in order to reduce sample sizes. A recent study has shown that the longitudinal FreeSurfer segmentation offers improved within session test-retest reproducibility relative to the cross-sectional segmentation at one 3T site using a nonstandard multi-echo MPRAGE sequence. In this study we implement a multi-site 3T MRI morphometry protocol based on vendor provided T1 structural sequences from different vendors (3D MPRAGE on Siemens and Philips, 3D IR-SPGR on GE) implemented in 8 sites located in 4 European countries. The protocols used mild acceleration factors (1.5-2) when possible. We acquired across-session test-retest structural data of a group of healthy elderly subjects (5 subjects per site) and compared the across-session reproducibility of two full-brain automated segmentation methods based on either longitudinal or cross-sectional FreeSurfer processing. The segmentations include cortical thickness, intracranial, ventricle and subcortical volumes. Reproducibility is evaluated as absolute changes relative to the mean (%), Dice coefficient for volume overlap and intraclass correlation coefficients across two sessions. We found that this acquisition and analysis protocol gives comparable reproducibility results to previous studies that used longer acquisitions without acceleration. We also show that the longitudinal processing is systematically more reliable across sites regardless of MRI system differences. The reproducibility errors of the longitudinal segmentations are on average approximately half of those obtained with the cross sectional analysis for all volume segmentations and for entorhinal cortical thickness. No significant differences in reliability are found between the segmentation methods for the other cortical thickness estimates. The average of two MPRAGE volumes acquired within each test-retest session did not systematically improve the across-session reproducibility of morphometry estimates. Our results extend those from previous studies that showed improved reliability of the longitudinal analysis at single sites and/or with non-standard acquisition methods. The multi-site acquisition and analysis protocol presented here is promising for clinical applications since it allows for smaller sample sizes per MRI site or shorter trials in studies evaluating the role of potential biomarkers to predict disease progression or treatment effects.
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Envejecimiento/patología , Algoritmos , Encéfalo/anatomía & histología , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Imagen por Resonancia Magnética/métodos , Reconocimiento de Normas Patrones Automatizadas/métodos , Estudios Transversales , Europa (Continente) , Femenino , Humanos , Estudios Longitudinales , Masculino , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
To investigate the increase in MRI contrast enhancement (CE) occurring in glioblastoma during the period between surgery and initiation of chemo-radiotherapy, thirty-seven patients with newly diagnosed glioblastoma were analyzed by early post-operative magnetic resonance (EPMR) imaging within three days of surgery and by pre-adjuvant magnetic resonance (PAMR) examination before adjuvant therapy. Areas of new CE were investigated by use of EPMR diffusion-weighted imaging and PAMR perfusion imaging (by arterial spin-labeling). PAMR was acquired, on average, 29.9 days later than EPMR (range 20-37 days). During this period an increased area of CE was observed for 17/37 patients. For 3/17 patients these regions were confined to areas of reduced EPMR diffusion, suggesting postsurgical infarct. For the other 14/17 patients, these areas suggested progression. For 11/17 patients the co-occurrence of hyperperfusion in PAMR perfusion suggested progression. PAMR perfusion and EPMR diffusion did not give consistent results for 3/17 patients for whom small new areas of CE were observed, presumably because of the poor spatial resolution of perfusion imaging. Before initiation of adjuvant therapy, areas of new CE of resected glioblastomas are frequently observed. Most of these suggest tumor progression, according to EPMR diffusion and PAMR perfusion criteria.
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Neoplasias Encefálicas/patología , Neoplasias Encefálicas/terapia , Glioblastoma/patología , Glioblastoma/terapia , Adulto , Anciano , Neoplasias Encefálicas/mortalidad , Terapia Combinada , Medios de Contraste , Imagen de Difusión por Resonancia Magnética , Progresión de la Enfermedad , Femenino , Glioblastoma/mortalidad , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Procedimientos Neuroquirúrgicos , Estudios Retrospectivos , Análisis de Supervivencia , Factores de TiempoRESUMEN
This case report describes the clinical, imaging, and pathological features of a case of Langerhans cell histiocytosis affecting a patient suffering from chronic thoracic spine pain. Spinal localizations of Langerhans cell histiocytosis have been rarely described and they are usually characterized by involvement of vertebral bodies with osteolytic lesions. Our case presented with several unusual features that delayed the diagnosis, including the age of patient and the involvement of left T10 costovertebral junction with relative sparing of vertebral body and costal bone. The clues for diagnosis were represented by increased signal intensity both on T 2W fat-saturated and T 1W images after administration of gadolinium. The diagnosis was finally confirmed by means of percutaneous biopsy with subsequent histological/immunohistochemical study.
RESUMEN
We analyzed the effect of afferent input on patterns of brain electrical activation in a 31-year-old man with progressive myoclonic epilepsy (PME) by measuring the somatosensory evoked potential (SSEP) amplitude at the scalp after median nerve stimulation and examining the changes in the functional magnetic resonance imaging blood oxygen level-dependent (fMRI BOLD) signal. High-amplitude SSEPs were elicited at the wrist in association with highly focal BOLD activation of the contralateral sensorimotor areas. By contrast, no diffuse activation of either the frontal or the posterior parietal cortical areas was observed, as seen in previously recorded data on SSEPs from a healthy control group. The highly focal BOLD activation in this patient suggests that cortex hyperexcitability might be limited to the sensorimotor cortex in PME. The combined EEG-fMRI findings highlight a dissociation between BOLD activation and neurophysiological findings.
Asunto(s)
Potenciales Evocados Somatosensoriales/fisiología , Imagen por Resonancia Magnética , Epilepsias Mioclónicas Progresivas/patología , Epilepsias Mioclónicas Progresivas/fisiopatología , Corteza Somatosensorial/irrigación sanguínea , Corteza Somatosensorial/fisiopatología , Adulto , Mapeo Encefálico , Electroencefalografía/métodos , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Oxígeno/sangre , Estimulación FísicaRESUMEN
The objective of the study was to compare the outcomes of a series of diagnostic parameters in Ménière's disease (MD) patients with the extent of endolymphatic hydrops (EH) as shown by magnetic resonance imaging (MRI) performed after intra-tympanic gadolinium administration using 18 patients (13 males and 5 females, age 25-78 years, median age 54.3 years) with definite MD. A 0.6-ml solution of Gadobutrol (1 mmol/ml) diluted 1:7 in saline was injected through the inferior-posterior quadrant of the tympanic membrane, using a 22-gauge spinal needle. The patient was kept with the head rotated 45° contralaterally for 30 min after the injection. Twenty-four hours later, three-dimensional fluid-attenuated inversion recovery MRI, using a 3-Tesla unit, was performed. Prevalence and extension of EH in MD patients was evaluated and correlated with age, duration and stage of the disease, frequency of attacks, time interval from the last attack, functional level scale, tinnitus, aural fullness, caloric stimulation, electrocochleography, and vestibular evoked myogenic potentials. All patients showed impaired enhancement of the inner ear of variable degree with the vestibular portion of the labyrinth more frequently involved than the cochlea. Abnormal vestibular evoked myogenic potentials, duration, and stage of the disease were significantly correlated to the number of inner ear sites involved. Modern imaging makes possible the identification of the endolymphatic hydrops in MD patients, improving diagnostic accuracy. The role of hydrops in the clinical manifestations and its correlation with most of the diagnostic parameters remain, however, not completely clear.
Asunto(s)
Medios de Contraste/administración & dosificación , Imagen por Resonancia Magnética , Enfermedad de Meniere/diagnóstico , Compuestos Organometálicos , Adulto , Anciano , Audiometría de Respuesta Evocada , Pruebas Calóricas , Oído Interno/patología , Hidropesía Endolinfática/diagnóstico , Femenino , Gadolinio , Humanos , Inyecciones , Masculino , Persona de Mediana Edad , Membrana Timpánica , Potenciales Vestibulares Miogénicos EvocadosRESUMEN
OBJECTIVE: To promote a better radiological interpretation of spine degeneration, a consistent standardization of the acquisition, interpretation and description of Magnetic Resonance Imaging (MRI) l findings. MATERIALS AND METHODS: In order to achieve this objective, a consensus among experts in imaging of degenerative spine disease (DSD) from Italian radiological societies (SIRM-Italian Society of Radiology, AINR-Italian Association of Neuroradiology) was achieved. The representatives of the Italian inter-societal working group examined the literature produced by European/American task forces on optimizing the study sequences, classification of degenerative disc changes, spondylo-arthrosis, osteochondrosis, synovial and ligament pathologies of the spinal column, and on canal and foraminal stenosis. The document-resulted from the consensus between experts-was then presented to the scientific societies of Neurosurgery (SINCH) and Orthopedics and Traumatology (SIOT) for their approval. RESULTS: This position paper presents a proposal for an optimized MRI protocol for studying DSD and provides a glossary of terms related to this pathology and indications on their use. The international terminological recommendations have been translated and adapted to the Italian language and clinical practice and clinical cases have been used to illustrate some of the main classifications. CONCLUSIONS: This revision of international DSD guidelines/recommendations and consensus made it possible to (1) update the nomenclature to international standards and (2) harmonize the MRI protocol and description of radiological findings, adapting both (1, 2) to the Italian context. With this position paper we intend to contribute to an improvement of the communication among doctors and between physicians and their patients as well as the quality of the radiological reports.