Multinodular and vacuolating neuronal tumor of the cerebrum is a recently reported benign, mixed glial neuronal lesion that is included in the 2016 updated World Health Organization classification of brain neoplasms as a unique cytoarchitectural pattern of gangliocytoma. We report 33 cases of presumed multinodular and vacuolating neuronal tumor of the cerebrum that exhibit a remarkably similar pattern of imaging findings consisting of a subcortical cluster of nodular lesions located on the inner surface of an otherwise normal-appearing cortex, principally within the deep cortical ribbon and superficial subcortical white matter, which is hyperintense on FLAIR. Only 4 of our cases are biopsy-proven because most were asymptomatic and incidentally discovered. The remaining were followed for a minimum of 24 months (mean, 3 years) without interval change. We demonstrate that these are benign, nonaggressive lesions that do not require biopsy in asymptomatic patients and behave more like a malformative process than a true neoplasm.

SUMMARY: Limbic encephalitis is far more common than previously thought. It is not always associated with cancer, and it is potentially treatable. Autoantibodies against various neuronal cell antigens may arise independently or in association with cancer and cause autoimmune damage to the limbic system. Neuroimaging plays a key role in the management of patients with suspected limbic encephalitis by supporting diagnosis and excluding differential possibilities. This article describes the main types of autoimmune limbic encephalitis and its mimic disorders, and emphasizes their major imaging features.ABBREVIATIONS: AME ϭ autoimmune-mediated encephalopathy; AMPAR ϭ ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid; CASPR2, contactin-asso-

-Purpose:A variety of diseases affect the calvaria. They may be identified clinically as palpable masses or incidentally in radiologic examinations. There are many diagnostic possibilities, including congenital, neoplastic, inflammatory and traumatic lesions. The purpose of this study is to illustrate the main calvarial lesions through MR imaging, their signal intensity and extension to neighboring sites. Method: A retrospective analysis of 81 cases, from November 1996 to July 2001, was conducted. The examinations were performed on a 1.5 T equipment and each one of the cases was pathologically proven. Conclusão: A RM detecta precocemente as alterações que envolvem a medula óssea, bem como demonstra acuradamente o envolvimento dos tecidos adjacentes. Este método é fundamental na avaliação detalhada das lesões da calota craniana.

Discovery of genetic abnormalities associated with neurodegeneration with brain iron accumulation (NBIA) has led to use of a genetic-based NBIA classification schema. Most NBIA subtypes demonstrate characteristic imaging abnormalities. While clinical diagnosis of NBIA is difficult, analysis of both clinical findings and characteristic imaging abnormalities allows accurate diagnosis of most of the NBIA subtypes. This article reviews recent updates in the genetic, clinical, and imaging findings of NBIA subtypes and provides a practical step-by-step clinicoradiological algorithm toward clinical diagnosis of different NBIA subtypes.

-Purpose: The typical manifestations of neurocysticercosis are described widely in the literature. The purpose of this study is to demonstrate the uncommon presentations of different forms of neurocysticercosis in MR imaging. Method: A retrospective analysis of 172 cases of neurocysticercosis in MR studies was carried out over a period of 13 years. One hundred and four males and 68 females with a mean age of 32 ± 3.7 years were studied. The studies were performed on 1.5 T GE MR units and T1 was used before and after gadolinium injection, T2 and gradient-echo (T2*) sequences. Results: The authors divided the unusual manifestations of neurocysticercosis into: intraventricular, subarachnoid, spinal, orbital, intraparenchymatous, and reactivation of previously calcified lesions. The results obtained were: intraparenchymatous 95 cases (55.23%); intraventricular 27 cases (15.69%); subarachnoid 20 cases (11.63%); spinal 6 cases (3.49%); orbital 1 case (0.58%); reactivated lesion 1 case (0.58%); association of intraventricular and intraparenchymatous 12 cases (6.98%); association of subarachnoid and intraparenchymatous 6 cases (3.49%); association of subarachnoid and intraventricular, 4 cases (2.32%). Conclusion: MR imaging is a sensitive and specific method in the analysis of different forms of unusual manifestations of neurocysticercosis, which should appear in the differential diagnosis of parenchymal, ventricular, spinal, cisternal, and orbital lesions.KEY WORDS: cysticercosis, parasites, MRI, subarachnoid space. Manifestações incomuns na ressonância magnética da neurocisticercose: análise de 172 casosRESUMO -Objetivo: as manifestações típicas da neurocisticercose já são bem conhecidas. O papel deste estudo foi demonstrar os aspectos incomuns da neurocisticercose na ressonância magnética. Método: foram analisados 172 casos de ressonância magnética de neurocisticercose na Med Imagem num período de 13 (treze) anos em aparelhos GE de 1.5T Signa (Horizon, LX e CVI). Dos casos analisados, foram diversas as formas de apresentação, incluindo intraventricular, intraespinhal, cisternal, orbital, formas atípicas parenquimatosas (simulando tumores), forma miliar e evolução não usual (reativação). Conclusão: A ressonância magnética é método sensível e específico na avaliação das numerosas formas de apresentação atípica da neurocisticercose, as quais devem constar no diagnóstico diferencial de lesões intraventriculares, cisternais, orbitárias e parenquimatosas. PALAVRAS-CHAVE: cisticercose, parasitas, ressonância magnética, espaço subaracnóide.

Dandy-Walker malformation (DWM) is the most common human cerebellar malformation, characterized by hypoplasia of the cerebellar vermis, cystic dilation of the fourth ventricle, and an enlarged posterior fossa with upward displacement of the lateral sinuses, tentorium, and torcular. Although its pathogenesis is not completely understood, there are several genetic loci related to DWM as well as syndromic malformations and congenital infections. Dandy-Walker malformation is associated with other central nervous system abnormalities, including dysgenesis of corpus callosum, ectopic brain tissue, holoprosencephaly, and neural tube defects. Hydrocephalus plays an important role in the development of symptoms and neurological outcome in patients with DWM, and the aim of surgical treatment is usually the control of hydrocephalus and the posterior fossa cyst. Imaging modalities, especially magnetic resonance imaging, are crucial for the diagnosis of DWM and distinguishing this disorder from other cystic posterior fossa lesions. Persistent Blake's cyst is seen as a retrocerebellar fluid collection with cerebrospinal fluid signal intensity and a median line communication with the fourth ventricle, commonly associated with hydrocephalus. Mega cisterna magna presents as an extraaxial fluid collection posteroinferior to an intact cerebellum. Retrocerebellar arachnoid cysts frequently compress the cerebellar hemispheres and the fourth ventricle. Patients with DWM show an enlarged posterior fossa filled with a cystic structure that communicates freely with the fourth ventricle and hypoplastic vermis. Comprehension of hindbrain embryology is of utmost importance for understanding the cerebellar malformations, including DWM, and other related entities.

Infectious diseases of the central nervous system (CNS), particularly those accompanied by the formation of granulomas, are a constant diagnostic challenge in some specific regions of the world, above all in developing countries. The pattern of image seen on CT or MR scan is the result of the inter-relations between the individual characteristics of the infectious agent and the capacity of each host to mount an appropriate inflammatory response to that specific type of aggression, inside one particular compartment of the CNS. Taking these parameters into account we will discuss the several patterns of image found in parasitic, bacterial, and fungal granulomatous infections.

No abstract