Leukodystrophies usually affect children, but in the last several decades, many instances of adult leukodystrophies have been reported in the medical literature. Because the clinical manifestation of these diseases can be nonspecific, MRI can help with establishing a diagnosis. A step-by-step approach to assist in the diagnosis of adult leukodystrophies is proposed in this article. The first step is to identify symmetric white matter involvement, which is more commonly observed in these patients. The next step is to fit the symmetric white matter involvement into one of the proposed patterns. However, a patient may present with more than one pattern of white matter involvement. Thus, the third step is to evaluate for five distinct characteristics-including enhancement, lesions with signal intensity similar to that of cerebrospinal fluid, susceptibilityweighted MRI signal intensity abnormalities, abnormal peaks at MR spectroscopy, and spinal cord involvement-to further narrow the differential diagnosis. ©

Childhood CNS cancer was also the top reason for cancer mortality in children in 2009 (2).Unlike neoplasms in other locations, primary brain tumors are not staged, but categorized according to the World Health Organization (WHO) 2016 Classification, which relies on molecular parameters in addition to histology to define their entities (3). Our goal is to offer an overview of these tumors, describing the imaging characteristics of the most common primary brain tumors in children based on the WHO classification update. We present the following article in accordance with the Narrative Review reporting checklist (http://dx.doi.

Background: Pediatric arterial ischemic stroke (AIS), which was thought to be a rare disorder, is being increasingly recognized as an important cause of neurological morbidity, thanks to new advances in neuroimaging. Objective: The aim of this study was to review the main etiologies of stroke due to arteriopathy in children. Methods: Using a series of cases from our institution, we addressed its epidemiological aspects, physiopathology, imaging findings from CT, MR angiography, MR conventional sequences and MR DWI, and nuclear medicine findings. Results: Through discussion of the most recent classification for childhood AIS (Childhood AIS Standardized Classification and Diagnostic Evaluation, CASCADE), we propose a modified classification based on the anatomical site of disease, which includes vasculitis, varicella, arterial dissection, moyamoya, fibromuscular dysplasia, Takayasu's arteritis and genetic causes (such as ACTA-2 mutation, PHACE syndrome and ADA-2 deficiency). We have detailed each of these separately. Conclusions: Prompt recognition of AIS and thorough investigation for potential risk factors are crucial for a better outcome. In this scenario, neurovascular imaging plays an important role in diagnosing AIS and identifying children at high risk of recurrent stroke.

There is still no scientific consensus on the existence of objective randomness. Understanding it is especially important for physics, as the probabilistic nature of quantum mechanics is believed to be irreducible. This theory aims to explain how the existence of true randomness is possible for the referential of a non-omniscient observer.The theory is constructed as a toy model over two thought experiments. We propose the concept of invisible and inaccessible laws as explanation for the occurrence of unpredictability and states that it represents the physical reification of Gödel's incompleteness theorem. The article proposes that the geometry of space-time is able to explain several physical phenomena as a subset of true random events. Among these are the event horizon in black holes, the hypersensitivity to initial conditions, and the Heisenberg's uncertainty principle. It is also able to refute the ideas of determinism in classical physics as well as to explain why deterministic Turing Machines are only able to execute pseudo-random number generators.

Leukodystrophies usually affect children, but in the last several decades, many instances of adult leukodystrophies have been reported in the medical literature. Because the clinical manifestation of these diseases can be nonspecific, MRI can help with establishing a diagnosis. A step-by-step approach to assist in the diagnosis of adult leukodystrophies is proposed in this article. The first step is to identify symmetric white matter involvement, which is more commonly observed in these patients. The next step is to fit the symmetric white matter involvement into one of the proposed patterns. However, a patient may present with more than one pattern of white matter involvement. Thus, the third step is to evaluate for five distinct characteristics ? including enhancement, lesions with signal intensity similar to that of cerebrospinal fluid, susceptibilityweighted MRI signal intensity abnormalities, abnormal peaks at MR spectroscopy, and spinal cord involvement ? to further narrow the differential diagnosis.