CNS metabolism in high-risk drug abuse : Insights gained from 1H-, 31P-MRS and PET.

BACKGROUND: High-risk drug consumption is a matter of great concern for public health actors in industrialised countries. The latest trends show a market tendency towards diversification and increasing demand for high-purity synthetic drugs. While most consumers seek medical help after cannabis use, it is high-risk drugs like cocaine, heroin and amphetamines that account for most of the 1000 drug-related deaths that occur in Germany every year. PURPOSE: This article presents the most prominent in vivo cerebral metabolic information in cocaine, heroin and methamphetamine users provided by MRI spectroscopy and PET imaging. MATERIALS AND METHODS: We reviewed the literature reporting neuroimaging studies of in vivo metabolic data for methamphetamine, cocaine and heroin consumption published up to March 2017. The search was conducted using PubMed and a combination of the following key words: methamphetamine, cocaine, heroin, MR spectroscopy, PET. CONCLUSION: MRI and PET are indispensable tools in gauging brain metabolic response to illegal drug abuse. Future breakthroughs in this field will most likely come from the investigation of novel neurotransmitter systems in PET and imaging phosphorus and carbon metabolites in MRI.

[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.

[CNS metabolism in high-risk drug abuse, German version : Insights gained from 1H- and 31P MRS and PET]. / ZNS-Stoffwechsel bei Missbrauch von Hochrisikodrogen : Erkenntnisse durch 1H- und 31P-MRS sowie PET.

BACKGROUND: High-risk drug consumption is a considerable problem for public health actors in industrialised countries. The latest trends show a market tendency towards diversification and increasing demand for high-purity synthetic drugs. Whilst most consumers seek medical help after cannabis use, it is high-risk drugs like cocaine, heroin and amphetamines that account for most of the 1000 drug-related deaths that occur in Germany every year. PURPOSE: This article presents the most prominent in vivo cerebral metabolic information in cocaine, heroin and methamphetamine users provided by MRI spectroscopy and PET imaging. MATERIALS AND METHODS: We reviewed the literature reporting neuroimaging studies of in vivo metabolic data for methamphetamine, cocaine and heroin consumption published up to March 2017. The search was conducted using PubMed with the following key words: methamphetamine, cocaine, heroin, MR spectroscopy, PET. CONCLUSION: MRI and PET are indispensable tools in gauging brain metabolic response to illegal drug abuse. Future breakthroughs in this field will most likely come from the investigation of novel neurotransmitter systems in PET and imaging phosphorus and carbon metabolites in MRI.

Front propagation in a regular vortex lattice: Dependence on the vortex structure.

We investigate the dependence on the vortex structure of the propagation of fronts in stirred flows. For this, we consider a regular set of vortices whose structure is changed by varying both their boundary conditions and their aspect ratios. These configurations are investigated experimentally in autocatalytic solutions stirred by electroconvective flows and numerically from kinematic simulations based on the determination of the dominant Fourier mode of the vortex stream function in each of them. For free lateral boundary conditions, i.e., in an extended vortex lattice, it is found that both the flow structure and the front propagation negligibly depend on vortex aspect ratios. For rigid lateral boundary conditions, i.e., in a vortex chain, vortices involve a slight dependence on their aspect ratios which surprisingly yields a noticeable decrease of the enhancement of front velocity by flow advection. These different behaviors reveal a sensitivity of the mean front velocity on the flow subscales. It emphasizes the intrinsic multiscale nature of front propagation in stirred flows and the need to take into account not only the intensity of vortex flows but also their inner structure to determine front propagation at a large scale. Differences between experiments and simulations suggest the occurrence of secondary flows in vortex chains at large velocity and large aspect ratios.

Front propagation in a vortex lattice: dependence on boundary conditions and vortex depth.

We experimentally address the propagation of reaction-diffusion fronts in vortex lattices by combining, in a Hele-Shaw cell and at low Reynolds number, forced electroconvective flows and an autocatalytic reaction in solution. We consider both vortex chains and vortex arrays, the former referring to mixed free/rigid boundary conditions for vortices and the latter to free boundary conditions. Varying the depth of the fluid layer, we observe no variation of the mean front velocities for vortex arrays and a noticeable variation for vortex chains. This questions the two-dimensional character of front propagation in low Reynolds number vortex lattices, as well as the mechanisms of this dependence.

[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.

[Degenerative and age-related alterations of the spine]. / Degenerative und altersbedingte Veränderungen an der Wirbelsäule.

Degenerative alterations of the spine occur in an individual-specific manner with increasing age. This is not only dependent on external factors, such as hard physical labor over many years but can also be genetically influenced as demonstrated in recent studies. The spinal cord is well-protected within the spinal canal but can be impaired by degenerative alterations of the intervertebral discs and functional spinal segments. Depositions or narrowing of nerve structures can cause lasting pain or focal neurological deficits, such as paralysis or sensitivity disorders. These complaints can slowly develop over years, e.g. by a gradually increasing bony narrowing of the spinal canal (spinal canal stenosis) or can occur suddenly, e.g. an acute herniated disc. However, low back pain is much more common and occurs in approximately 80 % of people sometime during their lifetime. It is necessary to recognize the normal age-related anatomical alterations in magnetic resonance imaging (MRI), particularly for intervertebral discs in order to interpret these correctly. Knowledge of the spectrum of the various age-related degenerative processes which can occur in intervertebral discs and vertebral bodies is necessary to be able to differentiate them from pathological alterations. This is important because therapy decisions are often made as a direct result of MRI.

Electrochemical growth of iron and cobalt arborescences under a magnetic field.

Pattern formation in the electrochemical deposition of the magnetic Fe and Co metals from thin layers of Fe(SO4) or Co(SO4) aqueous solutions were investigated in circular geometry and under magnetic field. Sparse arborescences with few thick branches and dense arborescences with many thin branches can be generated when no magnetic field is applied. Unlike for nonmagnetic metals, no tendency towards growth spiraling or asymmetric branching is found out in magnetic field normal to the plane of the growth. The morphology of the deposits appears instead to become more sparse. Under in-plane magnetic field, the sparse arborescences get into a needle morphology, oriented along the field, while the dense arborescences show a circular to rectangular morphology symmetry breaking, one edge of the rectangle being parallel to the field. Unexpected in most instances, these magnetic field effects cannot be understood without invoking the magnetic dipolar interaction inside the magnetized growing aggregate together with its interaction with the applied field.