Elevated brain glutamate levels in type 1 diabetes: correlations with glycaemic control and age of disease onset but not with hypoglycaemia awareness status

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In vivo 1 H MR spectroscopic imaging of aggressive prostate cancer: Can we detect lactate?

Contains fulltext : 138270.pdf (publisher's version ) (Closed access)PURPOSE: A semi-LASER sequence was optimized for in vivo lactate detection in the prostate. METHODS: The ethical committee waived the need for informed consent to measure 17 patients with high grade prostate cancer on a 3T system. A semi-LASER sequence was used with an echo time of 144 ms and optimized interpulse timing for a spectral citrate shape with high signal intensity. An LCModel basis set was developed for fitting choline, creatine, spermine, citrate, and lactate and was used to fit all spectra in tumor-containing voxels. For patients without detectable lactate, the minimal detectable lactate concentration was determined by adding in all spectra of tumor tissue a simulated lactate signal. The amplitude of the simulated lactate signal was iteratively decreased until its fit reached a Cramér Rao lower bound >20\%, which was then set as the patient-specific detection limit. RESULTS: In none of the patients a convincing lactate signal was found. We estimated that on average the lactate levels in high grade prostate cancer are below 1.5 mM (range 0.9-3.5 mM), Interestingly, in one patient with extensive necrosis in the tumor biopsy samples (Gleason score 5+5), large lipid resonances were observed, which originated from the tumor. CONCLUSION: The minimal detectable lactate concentration of 1.5 mM in high grade prostate cancer indicates that if lactate is increased it remains at low concentrations. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc

A comparison of sLASER and MEGA-sLASER using simultaneous interleaved acquisition for measuring GABA in the human brain at 7T

Contains fulltext : 215671.pdf (publisher's version ) (Open Access

Post-acquisition water-signal removal in 3D water-unsuppressed (1) H-MR spectroscopic imaging of the prostate.

PURPOSE: To develop a robust processing procedure of raw signals from water-unsuppressed MRSI of the prostate for the mapping of absolute tissue concentrations of metabolites. METHODS: Water-unsuppressed 3D MRSI data were acquired from a phantom, from healthy volunteers, and a patient with prostate cancer. Signal processing included sequential computation of the modulus of the FID to remove water sidebands, a Hilbert transformation, and k-space Hamming filtering. For the removal of the water signal, we compared Löwner tensor-based blind source separation (BSS) and Hankel Lanczos singular value decomposition techniques. Absolute metabolite levels were quantified with LCModel and the results were statistically analyzed to compare the water removal methods and conventional water-suppressed MRSI. RESULTS: The post-processing algorithms successfully removed the water signal and its sidebands without affecting metabolite signals. The best water removal performance was achieved by Löwner tensor-based BSS. Absolute tissue concentrations of citrate in the peripheral zone derived from water-suppressed and unsuppressed (1) H MRSI were the same and as expected from the known physiology of the healthy prostate. Maps for citrate and choline from water-unsuppressed 3D (1) H-MRSI of the prostate showed expected spatial variations in metabolite levels. CONCLUSION: We developed a robust relatively simple post-processing method of water-unsuppressed MRSI of the prostate to remove the water signal. Absolute quantification using the water signal, originating from the same location as the metabolite signals, avoids the acquisition of additional reference data

Implications of the magnetic susceptibility difference between grey and white matter for single-voxel proton spectroscopy at 7 T

Contains fulltext : 199479.pdf (publisher's version ) (Closed access

Effect of linewidth on estimation of metabolic concentration when using water lineshape spectral model fitting for single voxel proton spectroscopy at 7 T

Contains fulltext : 204427.pdf (publisher's version ) (Closed access)9 p

Creatine uptake in brain and skeletal muscle of mice lacking guanidinoacetate methyltransferase assessed by magnetic resonance spectroscopy.

Contains fulltext : 53723.pdf (publisher's version ) (Closed access)Creatine (Cr) levels in skeletal muscle and brain of a mouse model of Cr deficiency caused by guanidinoacetate methyltransferase absence (GAMT-/-) were studied after Cr supplementation with 2 g.kg body wt-1.day-1 Cr for 35 days. Localized 1H magnetic resonance spectroscopy (MRS) was performed in brain (cerebellum and thalamus/hippocampus) and in hind leg muscle of GAMT-/- mice before and after Cr supplementation and in control (Con) mice. As expected, a signal for Cr was hardly detectable in MR spectra of GAMT-/- mice before Cr supplementation. In the thalamus/hippocampus region of these mice, an increase in N-acetylasparate (NAA) was observed. During Cr administration, Cr levels increased faster in skeletal muscle compared with brain, but this occurred only during the first day of supplementation. Thereafter, Cr levels increased by 0.8 mM/day in all studied locations. After 35 days of Cr supplementation, Cr levels in all locations were higher compared with Con mice on a Cr-free diet and NAA levels normalized. Only because of the repeated MRS measurements performed in this longitudinal Cr supplementation study on GAMT-/- mice were we able to discover the initial faster uptake of Cr in skeletal muscle compared with brain, which may represent muscular Cr uptake independent of Cr transporter expression. Our results can provide the basis for additional experiments to optimize Cr supplementation in GAMT deficiency, as increases in brain Cr are slow in patients after Cr supplementation

Premier League Soccer: normal of inferior good?

Examiner si l'assistance aux matches de football a une élasticité revenu de la demande positive ou négative à partir d'un sondage pour établir le profil des spectateurs qui inclut également les coûts en matière de déplacement

Functional MRI techniques demonstrate early vascular changes in renal cell cancer patients treated with sunitinib: a pilot study.

Contains fulltext : 107957.pdf (publisher's version ) (Open Access)OBJECTIVE: To assess the early vascular effects of sunitinib in patients with renal cell carcinoma (RCC) with diffusion-weighted magnetic resonance imaging (DWI), dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and T2* perfusion MRI. PATIENTS AND METHODS: In 10 patients with abdominal RCC lesions, DWI, DCE-MRI and T2* perfusion MRI measurements at 3 Tesla were performed at baseline, 3 and 10 days after start of sunitinib. VEGF-A plasma levels were measured on days 0, 3 and 10. RESULTS: DWI showed a significant increase in the apparent diffusion coefficient (x10(-6) s/mm(2)) from baseline (mean 1158, range 814-2003) to day 3 (mean 1306, range 1008-2097, P = 0.015) followed by a decrease to baseline levels at day 10 (mean 1132, range 719-2005, P = 0.001). No significant changes were found in mean DCE-MRI parameters. T2* perfusion MRI showed a significant decrease in relative tumor blood volume (rBV) and relative tumor blood flow (rBF) at day 3 (rBV P = 0.037, rBF P = 0.018) and day 10 (rBV P = 0.006, rBF P = 0.009). VEGF-A plasma levels significantly increased after 10 days, but did not correlate with MRI parameters. CONCLUSIONS: Sunitinib induces antiangiogenic effects as measured by DWI and T2*-perfusion MRI, 3 and 10 days after the start of the initial treatment. DCE-MRI did not show significant changes. In the near future, early functional MRI-based evaluation can play an important role in tailoring treatment to the individual patient with RCC. Further investigation is warranted

Radiological imaging of teratological fetuses: what can we learn?

Contains fulltext : 174217.pdf (publisher's version ) (Open Access)OBJECTIVES: To determine the advantages of radiological imaging of a collection of full-term teratological fetuses in order to increase their scientific and educational value. BACKGROUND : Anatomical museums around the world exhibit full-term teratological fetuses. Unfortunately, these museums are regularly considered as "morbid cabinets". Detailed dysmorphological information concerning the exhibited specimens is often lacking. Moreover, fetuses with severe and complex congenital anomalies are frequently diagnosed incompletely, incorrectly or not at all. METHODS: In order to verify diagnoses and to enrich their educational and scientific value, we imaged 41 out of the 72 teratological specimens present in the collection of our Anatomy and Pathology Museum in Nijmegen (The Netherlands) by means of magnetic resonance imaging (MRI) and computed tomography (CT). Additionally, contemporary dysmorphological insights and 3D models are implemented in the teratology education of medical students and residents. CONCLUSIONS: Full-term teratological fetuses have become increasingly rare and deserve a prominent place in every anatomical museum; they are suitable for contemporary teratological research and education. Modern radiological techniques markedly enhance their scientific and didactic value. TEACHING POINTS: * To explore the scientific and educational potential of institutionalised teratological collections * To understand the additional value of radiological imaging in diagnosing teratological specimens * To learn about the specific settings of MRI parameters when scanning fixed specimens * To recognise specific internal dysmorphology in several congenital anomalies