Proton MR spectroscopy of the brain at 3 T: An update

Proton magnetic resonance spectroscopy (1H-MRS) provides specific metabolic information not otherwise observable by any other imaging method. 1H-MRS of the brain at 3 T is a new tool in the modern neuroradiological armamentarium whose main advantages, with respect to the well-established and technologically advanced 1.5-T 1H-MRS, include a higher signal-to-noise ratio, with a consequent increase in spatial and temporal resolutions, and better spectral resolution. These advantages allow the acquisition of higher quality and more easily quantifiable spectra in smaller voxels and/or in shorter times, and increase the sensitivity in metabolite detection. However, these advantages may be hampered by intrinsic field-dependent technical issues, such as decreased T2 signal, chemical shift dispersion errors, J-modulation anomalies, increased magnetic susceptibility, eddy current artifacts, challenges in designing and obtaining appropriate radiofrequency coils, magnetic field instability and safety hazards. All these limitations have been tackled by manufacturers and researchers and have received one or more solutions. Furthermore, advanced 1H-MRS techniques, such as specific spectral editing, fast 1H-MRS imaging and diffusion tensor 1H-MRS imaging, have been successfully implemented at 3 T. However, easier and more robust implementations of these techniques are still needed before they can become more widely used and undertake most of the clinical and research 1H-MRS applications. © Springer-Verlag 2007

www.elsevier.com/locate/ynimg Real-time independent component analysis of fMRI time-series

Real-time functional magnetic resonance imaging (fMRI) enables one to monitor a subject’s brain activity during an ongoing session. The availability of online information about brain activity is essential for developing and refining interactive fMRI paradigms in research and clinical trials and for neurofeedback applications. Data analysis for real-time fMRI has traditionally been based on hypothesis-driven processing methods. Off-line data analysis, conversely, may be usefully complemented by data-driven approaches, such as independent component analysis (ICA), which can identify brain activity without a priori temporal assumptions on brain activity. However, ICA is commonly considered a time-consuming procedure and thus unsuitable to process the high flux of fMRI data while they are acquired. Here, by specific choices regarding the implementation, we exported the ICA framework and implemented it into real-time fMRI data analysis. We show that, reducing the ICA input to a few points within a time-series in a sliding-window approach, computational times become compatible with real-time settings. Our technique produced accurate dynamic readouts of brain activity as well as a precise spatiotemporal history of quasistationary patterns in the form of cumulative activation maps and time courses. Results from real and simulated motor activation data show comparable performances for the proposed ICA implementation and standard linear regression analysis applied eithe

Prefrontal-Hippocampal Coupling During Memory Processing Is Modulated by COMT Val158Met Genotype

Background: Studies in humans and in animals have demonstrated that a network of brain regions is involved in performance of declarative and recognition memory tasks. This network includes the hippocampal formation (HF) as well as the ventrolateral prefrontal cortex (VLPFC). Studies in animals have suggested that the relationship between these brain regions is strongly modulated by dopamine. Methods: Using fMRI in healthy humans matched for a series of demographic and genetic variables, we studied the effect of the COMT val158met polymorphism on function of HF and VLPFC as well as on their functional coupling during recognition memory. Results: The COMT Val allele was associated with: relatively poorer performance at retrieval; reduced recruitment of neuronal resources in HF and increased recruitment in VLPFC during both encoding and retrieval; and unfavorable functional coupling between these two regions at retrieval. Moreover, functional coupling during retrieval was predictive of behavioral accuracy. Conclusions: These results shed new light on individual differences in responsivity and connectivity between HF and VLPFC related to genetic modulation of dopamine, a mechanism accounting at least in part for individual differences in recognition memory performanc

Cerebral neoplastic enhancing lesions: Multicenter, randomized, crossover intraindividual comparison between gadobutrol (1.0M) and gadoterate meglumine (0.5M) at 0.1mmolGd/kg body weight in a clinical setting

OBJECTIVE: Two macrocyclic extracellular contrast agents, one-molar neutral gadobutrol and ionic gadoterate meglumine, were compared to determine the overall preference for one or the other in a clinical setting. MATERIALS AND METHODS: Multicenter, randomized, single-blind, intra-individually controlled, comparison study with a corresponding blinded read. Efficacy analysis was based on 136 patients who underwent identical MRI examinations: group A first received 1.0M gadobutrol followed by 0.5M gadoterate meglumine 48 h to 7 days later; group B had a reversed administration order. Three independent blinded readers assessed off-site their overall diagnostic preference (primary efficacy parameter) based on a matched pairs approach. RESULTS: Superiority of gadobutrol over gadoterate meglumine was demonstrated for the qualitative assessment of overall preference across all readers by a statistically significant difference between both contrast agents for this primary endpoint. Preferences in lesion enhancement (secondary endpoint) were also found significantly in favor of gadobutrol. For preference in lesion delineation from surrounding tissue/edema and for internal structure only a trend towards a higher proportion for gadobutrol was found (except for internal structure reported by one reader, which showed a result of statistical significance). Lesion contrast and relative lesion enhancement (quantitative parameters) were statistically significantly higher for gadobutrol compared to gadoterate meglumine. CONCLUSION: Contrast-enhanced MRI of neoplastic brain lesions at a dose of 0.1 mmol Gd/kg body weight, assessed in a standardized off-site blinded reading, results in a significantly higher qualitative and quantitative preference for gadobutrol compared to gadoterate meglumine

Lemierre's syndrome complicated by cerebral venous sinus thrombosis: A life threatening and rare disease successfully treated with empiric antimicrobial therapy and conservative approach

Lemierre's syndrome (LS) is a "forgotten" condition characterized by septic thrombophlebitis of the jugular vein that follows an otolaryngological infection. Fusobacterium necrophorum is the aetiological agent responsible for the syndrome in adolescents and young adults whereas in older people even common bacteria are involved. Complications arise from spreading of septic emboli distally, i.e. to the brain, lungs, bones and internal organs everywhere in the body. We report a middle-aged woman who presented with headache and bilateral sixth cranial nerve palsy following a sphenoidal sinusitis and left mastoiditis. Imaging revealed thrombotic involvement of the left internal jugular vein as well as of several cerebral venous sinuses thrombosis (CVT). Currently, precise management protocols of LS with CVT complication do not exist although a combination of macrolides and second or third-generation cephalosporins, as well as anti-coagulants represent the mainstream of therapeutics. Surgical drainage is associated to remove septic foci but is burdened by severe complications and side effects. Complete recovery was achieved following pharmacological treatment in our patient. This report adds further evidence that LS complicated by CVT may be effectively treated adopting a conservative approach thus avoiding surgical drainage and severe complications