Brain and Behavioral Evidence for Reweighting of Vestibular Inputs with Long-Duration Spaceflight.

Microgravity alters vestibular signaling. In-flight adaptation to altered vestibular afferents is reflected in post-spaceflight aftereffects, evidenced by declines in vestibularly mediated behaviors (e.g., walking/standing balance), until readaptation to Earth's 1G environment occurs. Here we examine how spaceflight affects neural processing of applied vestibular stimulation. We used fMRI to measure brain activity in response to vestibular stimulation in 15 astronauts pre- and post-spaceflight. We also measured vestibularly-mediated behaviors, including balance, mobility, and rod-and-frame test performance. Data were collected twice preflight and four times postflight. As expected, vestibular stimulation at the preflight sessions elicited activation of the parietal opercular area ("vestibular cortex") and deactivation of somatosensory and visual cortices. Pre- to postflight, we found widespread reductions in this somatosensory and visual cortical deactivation, supporting sensory compensation and reweighting with spaceflight. These pre- to postflight changes in brain activity correlated with changes in eyes closed standing balance, and greater pre- to postflight reductions in deactivation of the visual cortices associated with less postflight balance decline. The observed brain changes recovered to baseline values by 3 months postflight. Together, these findings provide evidence for sensory reweighting and adaptive cortical neuroplasticity with spaceflight. These results have implications for better understanding compensation and adaptation to vestibular functional disruption.

Artificial intelligence in radiology: relevance of collaborative work between radiologists and engineers for building a multidisciplinary team.

The use of artificial intelligence (AI) algorithms in the field of radiology is becoming more common. Several studies have demonstrated the potential utility of machine learning (ML) and deep learning (DL) techniques as aids for radiologists to solve specific radiological challenges. The decision-making process, the establishment of specific clinical or radiological targets, the profile of the different professionals involved in the development of AI solutions, and the relation with partnerships and stakeholders are only some of the main issues that have to be faced and solved prior to starting the development of radiological AI solutions. Among all the players in this multidisciplinary team, the communication between radiologists and data scientists is essential for a successful collaborative work. There are specific skills that are inherent to radiological and medical training that are critical for identifying anatomical or clinical targets as well as for segmenting or labelling lesions. These skills would then have to be transferred, explained, and taught to the data science experts to facilitate their comprehension and integration into ML or DL algorithms. On the other hand, there is a wide range of complex software packages, deep neural-network architectures, and data transfer processes for which radiologists need the expertise of software engineers and data scientists in order to select the optimal manner to analyse and post-process this amount of data. This paper offers a summary of the top five challenges faced by radiologists and data scientists including tips and tricks to build a successful AI team.

The Variable Appearance of Third Ventricular Colloid Cysts: Correlation with Histopathology and the Risk of Obstructive Ventriculomegaly.

BACKGROUND AND PURPOSE: While third ventricular colloid cysts may present as an incidental finding, they also harbor the potential to cause ventricular obstruction and sudden death. Herein we analyze the relationship between imaging appearance and the risk of obstructive ventriculomegaly. MATERIALS AND METHODS: This is a retrospective review of the MR imaging appearance of 64 patients with colloid cysts, 46 of whom also had a CT scan, obtained by a tertiary hospital imaging report data base search over a 10-year period. Cysts were categorized by appearance on T2-FLAIR and correlated with patient age, cyst size, and the risk of obstructive ventriculomegaly. Histopathologic correlation was available for 28 cases. RESULTS: The 64-patient cohort was 52% female, median age 50 years (range 10 to 99 years). Cysts hyperintense on T2-FLAIR (53.1%) were larger (P <.001), occurred in younger patients (P = .01), and had a higher risk of obstructive ventriculomegaly than homogeneously hypointense cysts (relative risk 6.18, 95% CI [2.04, 18.67]). Three patterns of T2 hyperintensity were identified: homogeneously hyperintense, hyperintense rim, and cysts with "dot sign." Although "dot sign" cysts were larger (P < .001), there was no significant difference in patient age or the risk of ventricular obstruction among T2 hyperintense cysts. Cyst wall histopathology did not vary with imaging appearance. CONCLUSIONS: Hyperintensity on T2-FLAIR, whether homogeneous, rim, or "dot sign," is associated with larger cyst size and younger patient age, and is an imaging risk factor for obstructive ventriculomegaly. The hyperintense rim does not represent a thickened cyst wall.

Indentation and Transverse Diameter of the Meckel Cave: Imaging Markers to Diagnose Idiopathic Intracranial Hypertension.

BACKGROUND AND PURPOSE: Clinical and imaging manifestations of idiopathic intracranial hypertension should prompt early diagnosis and treatment to avoid complications. Multiple diagnostic imaging criteria are reported to suggest the diagnosis of idiopathic intracranial hypertension with questionable sensitivity and/or specificity. Increased intracranial pressure results in dilation of the perineural cisternal spaces such as the optic nerve sheaths and the Meckel cave. It may also cause protrusion of cisternal structures of the Meckel cave through the skull base foramina, which could result in indentation or a bilobed appearance of the Meckel cave. We investigated the changes in the Meckel cave in patients with proved idiopathic intracranial hypertension versus healthy controls. MATERIALS AND METHODS: We studied 75 patients with a diagnosis of idiopathic intracranial hypertension and 75 age-and sex-matched healthy controls. The transverse diameter of Meckel cave was measured in the axial and coronal planes of T2-weighted MR imaging sequences, and comparison was made between the 2 groups. RESULTS: The mean diameters of the Meckel cave on the coronal T2 plane in patients with idiopathic intracranial hypertension were 5.21 ± 1.22 mm on the right side and 5.16 ± 0.90 mm on the left side, while in the control group, they measured 3.89 ± 0.62 mm and 4.09 ± 0.68 mm, respectively (P value < .001). Of 75 patients with an approved diagnosis of idiopathic intracranial hypertension, 57 (76%) showed an indented Meckel cave as opposed to 21 (28%) in the control group. CONCLUSIONS: Our results confirm for the first time that the shape and size of the Meckel cave can be used as sensitive and specific diagnostic imaging markers for the diagnosis of idiopathic intracranial hypertension.

Imágenes del depósito de gadolinio en el sistema nervioso central / Images of gadolinio deposit in the central nervous system Abstract

Magnetic resonance imaging has been shown to be very useful in the diagnosis and monitoring of multiple diseases affecting the central nervous system. Gadolinium has been used extensively worldwide. It has been estimated that since its introduction more than two hundred million doses of GBCA have been administered globally. Gadolinium-based contrast agents (GBCAs) were long considered medicines with a high safety profile, the literature reports incidences of immediate adverse effects such as headache, dizziness, and altered sense of taste. Studies performed a few years after the introduction of GBCA showed that there were gadolinium deposits in the tissues but their clinical significance was not known. It wasn’t until 2006 when the first reports were published that associated the gadolinium ion tissue deposits from GBCA with a systemic inflammatory entity of the connective tissue similar to scleroderma known as Nephrogenic Systemic Fibrosis (NSF), in patients with chronic renal failure. In 2013, the association between the use of GBCAs and the progressive increase in the signal intensity of the dentate nucleus and the globus pallidus in T1-weighted MRI images without contrast medium, was described for the first time. This review describes the most relevant aspects of the pathophysiology of these findings taking into account their differential diagnosis.

Las imágenes por resonancia magnética han mostrado ser de gran utilidad en el diagnóstico y seguimiento de múltiples enfermedades que afectan el sistema nervioso central. El gadolinio se ha utilizado ampliamente a nivel mundial. Se estima que desde su introducción se han administrado más de doscientos millones de dosis de MCBG en el mundo. Los medios de contraste basados en Gadolinio (MCBG) fueron considerados por mucho tiempo medicamentos con un alto perfil de seguridad, la literatura reporta incidencia de efectos adversos inmediatos como cefalea, mareo y alteración del sentido del gusto. Estudios realizados pocos años después de la introducción de los MCBG mostraron que había depósitos de gadolinio en los tejidos, pero no se conocía su significancia clínica Fue hasta 2006 cuando se publicaron los primeros reportes que asociaban el depósito tisular del ion gadolinio proveniente de los MCBG con una entidad inflamatoria sistémica del tejido conectivo similar a la escleroderma conocida como Fibrosis Sistémica Nefrogénica (FSN) en pacientes con falla renal crónica. En 2013 se describió por primera vez la asociación entre el uso de los MCBG y el aumento progresivo de la intensidad de señal del núcleo dentado y los globos pálidos en las imágenes de RM ponderadas en T1 sin medio de contraste. En esta revisión se describen los aspectos más relevantes de la fisiopatología de estos hallazgos considerando su diagnóstico diferencial.

CT evaluation of caudal versus lumbar access to the intradural space.

BACKGROUND: Percutaneous intraspinal navigation is a new procedure that enables visualization of the central nervous system using a lumbar puncture technique. Past research shows promising potential, but is limited by damage to expensive fiberscopes due to the sharp angle of manipulation at L3-L4. Our objective in this study is to analyse the feasibility of a novel access through the sacral hiatus to eliminate this problem. METHODS: We retrospectively reviewed computed tomography images of the sacrum of 132 subjects, of which nine were excluded either secondary to incomplete imaging of the sacrum or variant anatomy that precluded any possible measurements. Of the remaining 123 patients, we measured kyphotic and lordotic curvature of the sacral canal in comparison to the angle of lumbar puncture. We also measured the anteroposterior diameters of the sacral canal at the distal, middle, and proximal portions. RESULTS: There were no significant differences according to sex or age. The kyphotic angle was a wide angle with a mean value of 167·89±11·71°. The lordotic angle had a mean value of 133·35±7·84°, making it 25·52° more obtuse than the average angle for lumbar puncture. The smallest diameter of the sacral canal was at the sacral hiatus and had a mean value of 4·49±1·66 mm. CONCLUSION: The size and anatomy of the sacral canal is feasible for PIN procedure and appears more favorable as compared to entry via lumbar puncture. The canal opening is wide enough to accommodate most small-diameter fiberscopes without difficulty, and the angles are obtuse enough to limit damage to the expensive fiberscopes.

Neuroimaging studies in Alzheimer's disease. A review.

Alzheimer's Disease (AD) is a progressive neurodegenerative disease associated with memory loss and gradual behavioral, functional and cognitive impairment. Conventional imaging studies, such as magnetic resonance or computed tomography have played a secondary role in AD diagnosis: While other causes of memory loss and cognitive deficit can be evaluated by these imaging methods, AD structural changes are not detected until very late in the course of the disease. Recent and more precise techniques have been developed to detect subtle changes not visualized with those imaging methods. This article presents a review of the neuroimaging techniques used as a diagnostic aid for AD.

Imaging of isolated cerebral mucormycosis. A report of three cases.

Mucormycosis is a rare infection in immunosupressed patients caused by fungi from the family Mucoraceae. Three types of disease spread have been described: rhinocerebral, systemic and isolated. Isolated spread is the most uncommon form, usually resulting in death. It has been described in diabetics, immunosupressed patients and intravenous drug abusers. Neuroimaging can aid the diagnosis of this entity, but biopsy remains the only reliable method. Imaging findings of Mucormycosis include abscesses and hemorrhagic or ischemic infarcts, usually in the basal ganglia and frontal lobes. Single or multiple lesions have been described as well as meningoencephalitis. Understanding these findings can help to detect the infection in an early stage. We describe three cases of isolated cerebral mucormycosis; all of them were intravenous drug abusers with one patient also being HIV positive.

Pielonefrenitis focal aguda en un niño imitando una masa / Acute focal pyelonephrenitis in a child imitating a mass

La pielonefritis focal aguda solo alcanza 5 por ciento de todas las infecciones urinarias: es poco frecuente en niños. Se presenta el caso de una paciente de 9 años con una masa renal, forma de ocurrencia poco usual de la pielonefritis aguda. Se revisan los hallazgos en urografía, ecografía y tomografía axial computarizada, su tratamiento y seguimiento

Pancreas ectopico en el coledoco / Ectopic pancreas in the coledoco

El páncreas heterotópico es tejido pancreático que se identifica histológicamente por fuera de los límites topográficos normales y que carece de conexiones anatómicas, vasculares o nerviosas con la glándula principal. Las localizaciones más frecuentes son el estómago, el duodeno y el yeyuno. Es una entidad muy importante por su alto riesgo de complicaciones dentro de las cuales se encuentra la malignización. Se presenta el caso de un paciente joven con ictericia obstructiva, la cual se presumió por causa neoplásica, resultando ectopia pancreática en la vía biliar, la cual es una entidad infrecuente (dos casos previos reportados)

Polipo uretral / Urethral polyp

Los pólipos uretrales son una patología benigna, poco común y cuya incidencia es desconocida. Cursan con sintomatología de obstrucción urinaria inferior, hematuria y otras presentaciones como retención urinaria. El diagnóstico suele realizarse mediante cistouretrografía miccional complementada con ecografía, y confirmado con cistoscopia. Estas estructuras fibroepiteliales suelen ser originadas en el veru montanum. A continuación se presenta un caso de pólipo uretral en un paciente de seis años con cuadro de obstrucción urinaria baja diagnosticado por medio de cistouretrografía miccional, asociado con reflujo vesicoureteral severo y nefropatía secundaria

Volvulo del ciego: reporte de un caso / Cecal volvulus: report of one case

El vólvulo del ciego es una entidad quirúrgica poco frecuente, con características radiológicas específicas. El diagnóstico clínico es muy pocas veces sospechado antes de la evaluación radiológica, la evaluación imaginológica es importante para detectar complicaciones como perforación o isquemia intestinal. Se reporta un caso con diagnóstico inicial imaginológico, con evolución post-operatoria satisfactoria se revisan los signos radiológicos característicos de esta entidad

Vigencia del diagnostico por sialografia convencional del sindrome de Sjogren / Conventional Sialography as still the firts election in diagnosis of Sjorgen's syndrome

El Síndrome de Sjógren (SS) y algunas otras enfermedades autoinmunes que pueden llegar a comprometer las glándulas salivares mayores, tienen manifestaciones radiológicas típicas en la Sialografia Convencional (SC). En los últimos años, con el advenimiento de nueva tecnología, se ha encontrado gran beneficio con el uso de la tomografía Axial Computadorizada (TAC) y la Resonancia Magnética (RM) en la evaluación de la gran mayoría de las enfermedades que afectan éstas glándulas. Sin embargo, dentro del marco de dichas enfermedades autoinmunes y especialmente el SS, la SC continúa siendo de primera elección en el diagnóstico de estadios tempranos de afección, lo cual no siempre es posible con las nuevas tecnologías. A continuación, se expone un caso de SS temprano diagnosticado por SC y anexamos dos casos que ilustran otros estadios de la enfermedad