Does superficial fat affect metabolite concentrations determined by MR spectroscopy with water referencing?

It has recently been reported in this journal that local fat depots produce a sizable frequency-dependent signal attenuation in magnetic resonance spectroscopy (MRS) of the brain. If of a general nature, this effect would question the use of internal reference signals for quantification of MRS and the quantitative use of MRS as a whole. Here, it was attempted to verify this effect and pinpoint the potential causes by acquiring data with various acquisition settings, including two field strengths, two MR scanners from different vendors, different water suppression sequences, RF coils, localization sequences, echo times, and lipid/metabolite phantoms. With all settings tested, the reported effect could not be reproduced, and it is concluded that water referencing and quantitative MRS per se remain valid tools under common acquisition conditions.

Focal Epilepsy: MR Imaging of Nonhemodynamic Field Effects by Using a Phase-cycled Stimulus-induced Rotary Saturation Approach with Spin-Lock Preparation.

Purpose To investigate whether nonhemodynamic resonant saturation effects can be detected in patients with focal epilepsy by using a phase-cycled stimulus-induced rotary saturation (PC-SIRS) approach with spin-lock (SL) preparation and whether they colocalize with the seizure onset zone and surface interictal epileptiform discharges (IED). Materials and Methods The study was approved by the local ethics committee, and all subjects gave written informed consent. Eight patients with focal epilepsy undergoing presurgical surface and intracranial electroencephalography (EEG) underwent magnetic resonance (MR) imaging at 3 T with a whole-brain PC-SIRS imaging sequence with alternating SL-on and SL-off and two-dimensional echo-planar readout. The power of the SL radiofrequency pulse was set to 120 Hz to sensitize the sequence to high gamma oscillations present in epileptogenic tissue. Phase cycling was applied to capture distributed current orientations. Voxel-wise subtraction of SL-off from SL-on images enabled the separation of T2* effects from rotary saturation effects. The topography of PC-SIRS effects was compared with the seizure onset zone at intracranial EEG and with surface IED-related potentials. Bayesian statistics were used to test whether prior PC-SIRS information could improve IED source reconstruction. Results Nonhemodynamic resonant saturation effects ipsilateral to the seizure onset zone were detected in six of eight patients (concordance rate, 0.75; 95% confidence interval: 0.40, 0.94) by means of the PC-SIRS technique. They were concordant with IED surface negativity in seven of eight patients (0.88; 95% confidence interval: 0.51, 1.00). Including PC-SIRS as prior information improved the evidence of the standard EEG source models compared with the use of uninformed reconstructions (exceedance probability, 0.77 vs 0.12; Wilcoxon test of model evidence, P < .05). Nonhemodynamic resonant saturation effects resolved in patients with favorable postsurgical outcomes, but persisted in patients with postsurgical seizure recurrence. Conclusion Nonhemodynamic resonant saturation effects are detectable during interictal periods with the PC-SIRS approach in patients with epilepsy. The method may be useful for MR imaging-based detection of neuronal currents in a clinical environment. (©) RSNA, 2016 Online supplemental material is available for this article.

Herrenbildnis Mr. H.... .... [Illustration]

Joseph Oppenheimer

Mr. A. M. L. Langdon [Illustration] : King's Council, (geb. 1861)

Scan von Monochrom-Mikroform

Mr. M. Alexander [Illustration] : King's Council; der gegenwärtige Präsident des Board of Deputies

Scan von Monochrom-Mikroform

Mr. Arthur Cohen [Illustration] : der bekannteste Jurist, juristischer Beirat des Königs von England, (geb. 1829)

Scan von Monochrom-Mikroform

Ms. lat. qu. 142 Abbildungsband - Catalogue de la collection de tableaux de Mr Frédéric Wilmans à Francfort s/M.

Alte Signatur: Art.Ff. 528

Gespräche über den Zionismus aus dem Haag : (Mr. Léon Bourgeois)

Bertha von Suttner

Ein Brief Mr. Robsons

W. S. Robson

Gespräche über den Zionismus aus dem Haag : (Mr. Léon Bourgeois)

Bertha von Suttner

Mr. Simon und die jüdische Mission

J. de H.

Eine Erklärung der englischen Regierung : Sir Clement Hill to Mr. L. J. Greenberg

Clement Hill

Eine Erklärung der englischen Regierung : Sir Clement Hill an Mr. L. J. Greenberg

Clement Hill