Kelly K. Koeller

Multiple sclerosis (MS) is the most important inflammatory demyelinating disorder that affects both the brain and spine. Dissemination in space and time on MRI is not limited to MS and can occur in neuromyelitis optica spectrum disorder (NMOSD) with aquaporin 4 antibodies, myelin oligodendrocyte glycoprotein-related antibody disease (MOGAD), and a series of other (inflammatory) demyelinating disorders. Spinal cord imaging is an important element of MS (differential) diagnosis and especially relevant in case of possible age-related vasculo-ischemic brain white matter lesions; a negative scan will help to rule out MS. Increasingly, MRI is used to monitor treatment and their complications such as progressive multifocal leukoencephalopathy (PML).

Common and noteworthy less common intradural extramedullary spinal neoplasms are highlighted, emphasizing radiologic manifestations that frequently suggest a specific diagnosis and provide important information for clinical and surgical management. While intradural extramedullary spinal disease varies widely, identification of tumors in this location and their radiologic manifestations greatly facilitates narrowing of the diagnostic considerations. Meningioma and schwannoma are the two most common intradural extramedullary tumors, and both are associated with neurofibromatosis. Meningiomas are most common in the thoracic spine and show a strong female predilection and a clinical manifestation related to compression of the spinal cord or nerve roots. Schwannomas typically are associated with radicular pain and other sensory symptoms. Melanotic schwannoma frequently shows T1 hyperintensity at MRI related to the presence of paramagnetic free radicals in melanin. Neurofibroma, known for its T2 hyperintensity, frequently involves the cervical spine, where it may make surgical resection challenging. Less commonly, malignant peripheral nerve sheath tumor commonly mimics the imaging appearance of a schwannoma but has decidedly more aggressive biologic behav...

Die Erkenntnisse zu Biologie und Verhalten der hochmalignen embryonalen Tumoren des Zentralnervensystems nehmen stetig zu. Das schlägt sich auch in ihrer sich über die Jahre wandelnden Terminologie und Klassifizierung nieder. Dieser Artikel stellt wichtige Änderungen des neuen Klassifikationsschemas der Weltgesundheitsorganisation 2016 vor, die für die Diagnostik und Tumorforschung in Zukunft den neuen Standard bilden werden. Embryonal tumors of the central nervous system (CNS) are highly malignant undifferentiated or poorly differentiated tumors of neuroepithelial origin and have been defined as a category in the World Health Organization (WHO) classification since the first edition of the “Blue Book” in 1979. This category has evolved over time to reflect our ever-improving understanding of tumor biology and behavior. With the most recent update in 2016, many previous histologic diagnoses incorporate molecular parameters for the first time (genetically defined entities). While medulloblastoma and atypical teratoid/rhabdoid tumor are familiar carryovers from the 2007 CNS WHO classification, there are major changes to the embryonal tumor category: for example, elimination of the term CNS primitive neuroectodermal tumor and addition of a new genetically defined entity, embryonal tumor with multilayered rosettes, C19MC-altered. The purpose of this article is to discuss both the radiologic-pathologic features of CNS embryonal tumors and the new molecularly defined types/subtypes that will become the standard classification/terminology for future diagnoses and tumor research.

Diese Übersichtsarbeit gibt anhand von Fallmaterial aus den Archiven des American Institute for Radiologic Pathology einen Überblick über ein breites Spektrum von ZNS-Infektionen durch Viren und Prionen sowie über die relevanten klinischen und neuroradiologischen Merkmale. Sie versteht sich als Ergänzung eines früheren Artikels zu bakteriellen, mykotischen und parasitären ZNS-Infektionen [1]. Viral infections of the central nervous system (CNS) range in clinical severity, with the most severe proving fatal within a matter of days. Some of the more than 100 different viruses known to affect the brain and spinal cord are neurotropic with a predilection for producing CNS infection. The host response to viral infection of the CNS is responsible for the pathophysiology and imaging findings seen in affected patients. Viral CNS infections can take the form of meningitis, encephalitis, encephalomyelitis, or, when involving the spinal cord and nerve roots, encephalomyeloradiculitis. In 1982, an infectious particle termed a prion that lacked nucleic acid and therefore was not a virus was reported to produce the fatal neurodegenerative disease Creutzfeldt-Jakob disease and related disorders. These prion diseases produce characteristic neuroimaging findings that are distinct from those seen in most viral infections. The clinical and imaging findings associated with viral CNS infection are often nonspecific, with microbiologic analysis of cerebrospinal fluid the most useful single test allowing for diagnosis of a specific viral infection. This review details the spectrum of viral CNS infections and uses case material from the archives of the American Institute for Radiologic Pathology, with a focus on the specific clinical characteristics and magnetic resonance imaging features seen in these infections. Where possible, the imaging features that allow distinction of these infections from other CNS inflammatory conditions are highlighted.

This review article discusses both the radiologic-pathologic features of central nervous system embryonal tumors and the new molecularly defined types and subtypes that will become the standard classification/terminology for future diagnoses and tumor research. Embryonal tumors of the central nervous system (CNS) are highly malignant undifferentiated or poorly differentiated tumors of neuroepithelial origin and have been defined as a category in the World Health Organization (WHO) classification since the first edition of the “Blue Book” in 1979. This category has evolved over time to reflect our ever-improving understanding of tumor biology and behavior. With the most recent update in 2016, many previous histologic diagnoses incorporate molecular parameters for the first time (genetically defined entities). While medulloblastoma and atypical teratoid/rhabdoid tumor are familiar carryovers from the 2007 CNS WHO classification, there are major changes to the embryonal tumor category: for example, elimination of the term CNS primitive neuroectodermal tumor and addition of a new genetically defined entity, embryonal tumor with multilayered rosettes, C19MC-altered. The purpose of this article is to discuss both the radiologic-pathologic features of CNS embryonal tum...

This article explores the broad spectrum of viral and prion central nervous system infections, highlights clinical and neuroimaging features of special interest, and serves as a complementary installment to an earlier article published in this journal on bacterial, fungal, and parasitic central nervous system infections. Viral infections of the central nervous system (CNS) range in clinical severity, with the most severe proving fatal within a matter of days. Some of the more than 100 different viruses known to affect the brain and spinal cord are neurotropic with a predilection for producing CNS infection. The host response to viral infection of the CNS is responsible for the pathophysiology and imaging findings seen in affected patients. Viral CNS infections can take the form of meningitis, encephalitis, encephalomyelitis, or, when involving the spinal cord and nerve roots, encephalomyeloradiculitis. In 1982, an infectious particle termed a prion that lacked nucleic acid and therefore was not a virus was reported to produce the fatal neurodegenerative disease Creutzfeldt-Jakob disease and related disorders. These prion diseases produce characteristic neuroimaging findings that are distinct from those seen in most viral infections. The clinical and imaging findings associated with viral CNS infection are often nonspecifi...

Imaging evaluation of sinonasal tumors is most often conducted with computed tomography, which excels at identifying the effects of these masses on adjacent osseous structures, and magnetic resonance imaging that is ideal for distinguishing pathologic masses from mucosal thickening and fluid that are common in the sinonasal spaces and depicting extension into the surrounding soft tissues, orbits, and intracranial compartment. Accordingly, the two studies are complementary exams and both are commonly utilized in the assessment of these masses. Less commonly, positron emission tomography can provide additional metabolic evaluation of potential metastatic disease in patients with malignant disease. While these imaging modalities are excellent for the portrayal of an abnormality, there is considerable overlap in the imaging appearance of these tumors and specific imaging manifestations linked to a particular tumor are frequently lacking. Therefore, while the mass may be readily identified, narrowing the differential diagnosis to a single specific entity is rare. Nevertheless, cross-sectional imaging plays an essential role in patient management and valuable guidance for successful biopsy or surgical resection in virtually all cases. This review emphasizes essential imaging manifestations that correlate with sinonasal tumors in general and highlight certain features that may implicate a specific disease process.

Trotz beachtlicher Fortschritte in Prävention und Behandlung bleiben Infektionskrankheiten mit Beteiligung des zentralen Nervensystems eine wichtige Morbiditäts- und Mortalitätsursache, insbesondere in weniger entwickelten Ländern und bei immunkompromittierten Personen. Bakterielle, Pilz- und parasitäre Pathogene sind lebende Organismen und greifen Gehirn, Rückenmark oder Hirnhäute an. Infektionen durch diese Pathogene sind mit vielfältigen Mustern in der Neurobildgebung assoziiert, die sich in den meisten Fällen am besten in der Magnetresonanztomografie darstellen lassen. Bakterielle Infektionen – am häufigsten auf Streptokokken-, Haemophilus- und Neisseria-Spezies zurückzuführen – verursachen eine signifikante Meningitis, während die weniger häufige Zerebritis und die anschließende Abszessbildung eine gut dokumentierte Progression aufweisen, mit zunehmend hervortretender Veränderung der Signalintensität und entsprechender Kontrastmittelanreicherung. Atypische bakterielle Infektionen sind durch die Entwicklung einer granulomatösen Reaktion charakterisiert, die klassischerweise bei der Tuberkulose beobachtet wird; dabei ist das Tuberkulom die häufigste parenchymale Form der Erkrankung. Durch Spirochäten und Rickettsien verursachte Erkrankungen sind weniger häufig. Pilzinfektionen herrschen bei immunkompromittierten Wirten vor und werden durch Hefepilze, Schimmelpilze und dimorphe Pilze verursacht. Die Kryptokokkenmeningitis ist die häufigste Pilzinfektion, während die Candidiasis die häufigste nosokomiale Infektion ist. Mukormykose und Aspergillose sind angioinvasiv und gehen mit einer hohen Morbidität und Mortalität bei immunkompromittierten Patienten einher. Hinsichtlich einer potenziellen weltweiten Exposition sind parasitäre Infektionen, darunter Neurozystizerkose, Toxoplasmose, Echinokokkose, Malaria und Schistosomiasis, die größte Bedrohung. Seltene Amöbeninfektionen sind wegen ihrer extremen Virulenz und hohen Mortalität erwähnenswert. Das Ziel dieses Artikels ist es, die in der Neurobildgebung charakteristischen Manifestationen von Infektionen durch Bakterien, Pilze und Parasiten hervorzuheben; dabei liegt der Schwerpunkt auf der radiologisch-pathologischen Korrelation und dem historischen Rückblick. Despite remarkable progress in prevention and treatment, infectious diseases affecting the central nervous system remain an important source of morbidity and mortality, particularly in less-developed countries and in immunocompromised persons. Bacterial, fungal, and parasitic pathogens are derived from living organisms and affect the brain, spinal cord, or meninges. Infections due to these pathogens are associated with a variety of neuroimaging patterns that can be appreciated at magnetic resonance imaging in most cases. Bacterial infections, most often due to Streptococcus, Haemophilus, and Neisseria species, cause significant meningitis, whereas the less common cerebritis and subsequent abscess formation have well-documented progression, with increasingly prominent altered signal intensity and corresponding contrast enhancement. Atypical bacterial infections are characterized by the development of a granulomatous response, classically seen in tuberculosis, in which the tuberculoma is the most common parenchymal form of the disease; spirochetal and rickettsial diseases are less common. Fungal infections predominate in immunocompromised hosts and are caused by yeasts, molds, and dimorphic fungi. Cryptococcal meningitis is the most common fungal infection, whereas candidiasis is the most common nosocomial infection. Mucormycosis and aspergillosis are characterized by angioinvasiveness and are associated with high morbidity and mortality among immunocompromised patients. In terms of potential exposure in the worldwide population, parasitic infections, including neurocysticercosis, toxoplasmosis, echinococcosis, malaria, and schistosomiasis, are the greatest threat. Rare amebic infections are noteworthy for their extreme virulence and high mortality. The objective of this article is to highlight the characteristic neuroimaging manifestations of bacterial, fungal, and parasitic diseases, with emphasis on radiologic-pathologic correlation and historical perspectives. ¹ © 2015 The Radiological Society of North America. All rights reserved. Originally puplished in English in RadioGraphics 2015; 35: 1141 – 1169. Online published in 10.1148/rg.2015140317. Translated and reprinted with permission of RSNA. RSNA is not responsible for any inaccuracy or error arising from the translation from English to German.