[Malignant tumors of the skull base]. / Maligne Tumoren der Schädelbasis.

Malignant skull base tumors consist of a heterogeneous group of malignancies that can be divided into primary and secondary (metastatic) skull base tumors. In addition, according their anatomical location, they can be further divided into tumors of the anterior, middle, or posterior cranial fossa. Although malignant skull base tumors do not rigorously respect anatomical borders, their anatomical occurrence can potentially be helpful for possible differential diagnosis. This article is focused on the most common malignant tumors of the skull base and their imaging and clinical presentations.

[Spina bifida]. / Spina bifida.

Spina bifida is a congenital disorder with incomplete closure of the spinal column due to a bony vertebral defect. The term spina bifida literally means cleft spine and is used as a generic term of spinal dysraphism (Greek: Raphe = seam). It is a midline defect that occurs during the embryonic period. The insufficient closure of one or more vertebral arches is the result of an incomplete junction of the neural tube. Depending on the extent of the neural tube defect, various types of spina bifida can be differentiated. Closed spinal dysraphisms, also known as spina bifida occulta, are solely characterized by a bony defect of the vertebral arch, whereas, spina bifida cystica (synonym: open spina bifida or spina bifida aperta) can be distinguished by a protruding cyst, containing either meninges or meninges in combination with spinal cord tissue and are defined as open spinal dysraphisms.

[Pediatric brain tumors]. / Kindliche Hirntumoren.

Brain tumors differ between children and adults both in histology and localization. Malignant gliomas and meningiomas predominate in adults while medulloblastomas and low-grade astrocytomas are the most frequent brain tumors in children. More than one half (50-70%) of pediatric brain tumors have an infratentorial location but only approximately 30% in adults. Brain tumors can be recognized in sonography, cranial computed tomography (CCT) and magnetic resonance imaging (MRI) by their space-consuming character and by their divergent density and intensity in comparison to normal brain parenchyma. They can grow extrusively, even infiltrate the parenchyma or originate from it. Besides clinical symptoms and diagnostics this article describes the most common pediatric brain tumors, i.e. astrocytoma, medulloblastoma, brainstem glioma, craniopharyngioma, neurofibromatosis and ganglioglioma. The most important imaging criteria are outlined.

[Extra-axial tumors of the central nervous system]. / Extraaxiale Tumoren des zentralen Nervensystems.

Extra-axial tumors are intracranial neoplasms but are not located within the brain parenchyma. The localization of intracranial neoplasms helps to narrow down the possible differential diagnoses and also plays a deciding role in the treatment strategy and the prognosis. For this reason exact localization of these lesions is extremely important. Extra-axial tumors are the most common neoplasms among adults. They can be divided in a broad spectrum of histopathological subgroups. The most common extra-axial tumors are meningiomas, which arise from the dura mater. In the vast majority of cases they are benign and slowly growing. Only a few rare subgroups show aggressive behavior.

[Orbit : Part 2: Diseases of the globe and retrobulbar space]. / Orbita : Teil 2: Retrobulbäre und bulbäre Erkrankungen.

After the first part of the article focused on the anatomy of the orbit and the anatomical relations of the orbital cavity, the second part provides an overview of common diseases of the globe and the retrobulbar space. The main focus is to describe and analyze current imaging procedures and their respective advantages. In addition to inflammatory lesions, traumatic, neoplastic, and congenital entities are also described.

The Derivo Embolization Device, a Second-Generation Flow Diverter for the Treatment of Intracranial Aneurysms, Evaluated in an Elastase-Induced Aneurysm Model.

PURPOSE: In recent years, flow diverters have provided a promising alternative to treat complex intracranial aneurysms. In this study, we compare a second-generation flow-diverting device (Derivo Embolization Device) with its prototype flow diverter, in the treatment of elastase-induced aneurysms in New Zealand white rabbits. METHODS: The Derivo Embolization Device is a self-expanding stent consisting of 48 nitinol wires. The device was implanted across the necks of 17 elastase-induced aneurysms in New Zealand white rabbits. One additional device was implanted in the abdominal aorta of each animal covering the origin of lumbar arteries. Follow-up was performed after 3 months (n = 8) and 6 months (n = 9) under continuous double antiplatelet therapy. Statuses of angiographic and histological aneurysm occlusion as well as patency of branch arteries and neointimal growth were evaluated and compared with its prototype flow diverter. RESULTS: The Derivo Embolization Device provided advanced visibility and flexibility, which led to more accurate navigation and placement. Complete aneurysm occlusion rates were noted in 15 cases (88 %), respectively, compared with 5 cases (28 %) with the first-generation device (p = 0.001). Neointimal growth and diameter stenosis were significantly less with the Derivo Embolization Device and declining after 6 months follow-up in the abdominal aorta. Extreme device oversizing led to distal occlusion of the parent vessel in three cases. Covered branch arteries remained patent throughout the entire period of observation. CONCLUSIONS: The Derivo Embolization Device provides excellent occlusion of elastase-induced aneurysms while preserving branch arteries.

Superficial Siderosis after Germinal Matrix Hemorrhage.

BACKGROUND AND PURPOSE: Germinal matrix hemorrhage is a frequent complication of prematurity and can be associated with adverse neurodevelopmental outcome, depending on its severity. In addition to parenchymal damage, intraventricular residues of hemorrhage and hydrocephalus MR imaging findings include superficial siderosis. The purpose of this study was to investigate the prevalence and location of superficial siderosis in patients with a history of germinal matrix hemorrhage. MATERIALS AND METHODS: We retrospectively identified patients with a history of germinal matrix hemorrhage who underwent MR imaging in our institution between 2008 and 2016. Imaging was evaluated for the presence and location of superficial siderosis. The presence of subependymal siderosis and evidence of hydrocephalus were assessed. RESULTS: Thirty-seven patients with a history of germinal matrix hemorrhage were included; 86.5% had preterm births. The mean age at the first MR imaging was 386 days (range 2-5140 days). The prevalence of superficial siderosis was 67.6%. Superficial siderosis was detected significantly more often when MR imaging was performed within the first year of life (82.8% versus 12.5%, P < .000). When present, superficial siderosis was located infratentorially in all cases, while additional supratentorial superficial siderosis was detectable in 27%. CONCLUSIONS: Here we report that superficial siderosis is a common MR imaging finding in the first year of life of patients with a history of germinal matrix hemorrhage, but it dissolves and has a low prevalence thereafter. A prospective analysis of its initial severity and speed of dissolution during this first year might add to our understanding of the pathophysiology of neurodevelopmental impairment after germinal matrix hemorrhages.

[Mechanical thrombectomy - technique]. / Mechanische Thrombektomie - Technik.

Mechanical thrombectomy with stent retrievers in acute stroke has emerged as the technique with the highest recanalization rate of therapeutic procedures available so far. Recently it was demonstrated that compared to intravenous rTPA alone, mechanical thrombectomy improves outcomes of patients with acute occlusions of intracranial arteries of the anterior circulation in several randomized clinical trials. In this article we will give an overview of the steps required for the thrombectomy procedure.

[Pitfalls in mechanical recanalization]. / "Pitfalls" bei mechanischer Rekanalisation.

Recently multiple studies demonstrated the advantage of mechanical thrombectomy after thrombotic stroke onset in proximal intracranial arteries over i.v. thrombolysis. In experienced stroke centers, recanalization rates of up to 90% can be achieved. This article is dealing with various pitfalls which could face the interventionalist during endovascular therapy and can complicate or even make the procedure impossible.

Intermediate Catheters Reduce the Length of Mechanical Thrombectomy Procedures in Acute Basilar Artery Occlusions.

BACKGROUND AND PURPOSE: In the past years, technical developments have raised recanalization rates of endovascular treatments of intracerebral artery occlusions in acute ischemic stroke. By using stent retrievers, several prospective trials have reported recanalization rates up to 79 % as well as good neurological outcome in up to 58 % of the cases. The degree of the recanalization and the length of the procedure are factors known to influence the clinical outcome of patients treated endovascularly. Yet, still little is known about factors influencing the angiographic results of thrombectomy procedures. The purpose of this study was to investigate whether the use of intermediate catheters affects the angiographic results of thrombectomy procedures in basilar artery occlusions. MATERIALS AND METHODS: A total of 47 consecutive patients with acute basilar artery occlusions who underwent endovascular treatment with stent retrievers in our department were retrospectively identified. We analyzed the angiographic data regarding the use of intermediate catheters, the lengths of the procedures, the number of passes of the stent retrievers, the angiographic results, and the site of access to the basilar artery. RESULTS: Recanalization with modified thrombolysis in cerebral infarction (mTICI) ≥ 2b was achieved in 74.5 %. Intermediate catheters were used in 13 cases. The mean length of the procedures was significantly shorter when intermediate catheters were used (44.8 ± 27.6 vs. 70.7 ± 41.4 min, P = .043). There were no significant differences in the number of passes or in the final mTICI scores. CONCLUSIONS: The use of intermediate catheters significantly reduces the length of mechanical thrombectomy procedures in acute basilar artery occlusions.

[Mechanical Thrombectomy - Recent Trials]. / Mechanische Thrombektomie - Studienlage.

BACKGROUND: The publications of five prospective randomized trials have made 2015 a milestone in the development of stroke therapy. Up till then, IV rtPA had been the only evidence-based recanalizing treatment for ischemic stroke. AIM: In this article we review the results of five trials: MR CLEAN, ESCAPE, EXTEND IA, SWIFT PRIME, and REVASCAT.

[Differential diagnostics of dementia type diseases]. / Differenzialdiagnose demenzieller Erkrankungen.

Dementia remains the most common neuropsychiatric disease in elderly people. This is not only a great burden for the affected person, but also for the entire society. Currently, it is estimated that more than one million people in Germany suffer from dementia. The incidence is about 244,000 people per year. There are different forms of dementia. Primary dementia is caused by neurodegenerative or vascular diseases. Approximately 90% of all dementia types in people over 65 years of age are primary. Secondary dementia includes organic illness, which leads to dementing syndromes. Traumatic brain injury, tumor, medication and toxic substances, for instance, belong to these. Usually, if the underlying disease can be treated effectively, mental performance and cognition can be returned to normal.

[MRI in dementia-type diseases]. / MRT bei demenziellen Erkrankungen.

Dementia-inducing conditions represent a leading cause of disability and are a major health concern in industrialized countries. The burden these conditions put on society is certain to rise in the context of an ever-increasing elderly population. As these conditions feature an insidious onset and overlapping clinical features, imaging is a powerful tool in refining the diagnosis and assessing the progression of dementing conditions. The radiologist needs to be aware of and be able to detect underlying pathologies which could be reversible. Furthermore, imaging is important not only in excluding other pathologies but also in improving diagnostic accuracy. This article presents the typical clinical presentations as well as magnetic resonance imaging (MRI) features of the degenerative and the non-degenerative causes of dementia. The focus is on the core knowledge for MRI diagnostics in dementing conditions and a brief presentation of the latest MRI techniques which may become a part of standard imaging protocols in the future.

[Germ cell and embryonal tumors]. / Keimzell- und embryonale Tumoren.

Germ cell tumors, which constitute approximately 3-5% of tumors of the central nervous system (CNS), can be subdivided into germinomas, embryonal carcinomas, yolk sac tumors, choriocarcinomas, teratomas and mixed germ cell tumors. The diagnosis of intracranial germ cell tumor is based on the clinical symptoms, detection of tumor markers, such as alpha fetoprotein (AFP) and the beta subunit of human chorionic gonadotropin (beta-hCG) in blood and cerebrospinal fluid (CSF), magnetic resonance imaging (MRI) of the brain and spinal cord, CSF cytology and histology. The diagnosis of a secreting germ cell tumor, i.e. a non-germinoma, can be made by the determination of AFP and hCG as tumor markers. Germinomas are radiosensitive but are equally as sensitive to chemotherapy. Teratomas of the CNS are mostly diagnosed in newborns and infants. The most decisive role in the treatment of teratomas is played by as complete a resection as possible. Chemotherapy and irradiation play a subordinate role.Embryonal tumors, which constitute approximately 15-20% of CNS tumors, include medulloblastomas, primitive neuroectodermal tumors (PNET) of the CNS and the atypical teratoid rhabdoid tumor of the CNS. Medulloblastoma is the most common malignant brain tumor in childhood and adolescence. The incidence peak is the fifth year of life with a male predisposition in a ratio of 1.5:1. Medulloblastomas constitute 12-25% of all pediatric CNS tumors and 30-40% of pediatric tumors of the posterior cranial fossa. At the time of diagnosis evidence of dissemination in the CSF cavity is found in approximately 40% of patients. The extreme cell density makes medulloblastomas hyperdense in computed tomography (CT) and can therefore be differentiated from hypodense astrocytomas. The PNETs are histologically related to medulloblastomas, pineoblastomas, atypical teratoid rhabdoid tumors and peripheral neuroblastomas. They are relatively rare in children constituting less than 5% of supratentorial neoplasms. Patients are mostly clinically conspicuous due to macrocephalus and signs of brain pressure and/or seizures. In native CT the solid components of PNETs show a hyperdensity compared to the surrounding brain parenchyma probably due to the high cell density. Cysts and calcification are often detectable. The survival rate of children with CNS tumors has continuously increased in recent years. When corresponding clinical symptoms appear, such as headache, nausea or vomiting when fasting, all of which are evidence of increased intracranial pressure, MRI should be carried out as quickly as possible. Children should be treated in centers with departments of pediatric oncology and hematology and within the framework of studies.