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Purpose: To establish the feasibility of using vessel‐encoded pseudocontinuous arterial spin labeling (VEPCASL) for noninvasive vascular territory imaging (VTI) and artery‐specific dynamic angiography of a large number of arterial branches above the circle of Willis within a clinically feasible scan time. Methods: 3D time‐of‐flight angiography was used to select a labeling plane and establish 7 pairs of encoding cycles. These were used for VEPCASL VTI and dynamic 2D angiography (8 min and 3 min acquisition times, respectively) in healthy volunteers, allowing the separation of signals arising from 13 arterial branches (including extracranial arteries) in postprocessing. To demonstrate the clinical potential of this approach, VEPCASL angiography was also applied in 5 patients with brain arteriovenous malformation (AVM). Results: In healthy volunteers, the artery‐specific filling of the vascular tree and resulting perfusion territories were well depicted. SNRs were approximately 5 times higher than those achievable with single‐artery selective methods. Blood supply to the AVMs was well visualized in all cases, showing the main feeding arteries and venous drainage. Conclusions: VEPCASL is a highly efficient method for both VTI and dynamic angiography of a large number of arterial branches, providing a comprehensive picture of vascular flow patterns and the effect on downstream tissue perfusion within an acceptable scan time. Automation of labeling plane and vessel‐encoding selection would improve robustness and efficiency, and further refinement could allow quantitative blood flow measurements to be obtained. This technique shows promise for visualizing the blood supply to lesions and collateral flow patterns. [ABSTRACT FROM AUTHOR]

Purpose Assessing the functionality of muscle fibers is essential to monitor both pathological and physiological processes. Here, we present a new method for accurate, quantitative measurement of muscle contraction with magnetic resonance imaging (MRI) using an electrical muscle stimulator (EMS), hence allowing the direct assessment of muscle kinematics. Methods A commercially available EMS device was used to induce involuntary periodic muscle contraction of the vastus lateralis muscle (VL) synchronized with high-temporal-resolution cine phase contrast MRI acquisition at 3T. The proposed method was evaluated in ten male volunteers at varying levels of stimulation (10-18 mA) and maximum velocity, strain, and strain rate were calculated offline. Results Artifact-free velocity, strain and strain rate maps were produced and were consistent across the volunteers. Quantitatively, all parameters varied significantly at different levels of stimulation, in an approximately power-law dependence on the stimulation current. At 18 mA maximum contraction speeds at the beginning of the contraction were 4.28 ± 2.64 cm/s; principal strain was 0.30 ± 0.12; and positive in-plane strain rate was 0.25 ± 0.14 s−1. Conclusion MRI of EMS-controlled involuntary muscle contraction is feasible and allows offline calculation of velocity, strain and strain rate maps, which appear to depend significantly on the stimulation current used. Magn Reson Med 77:664-672, 2017. © 2016 International Society for Magnetic Resonance in Medicine [ABSTRACT FROM AUTHOR]

Background and Purpose: This study assesses whether magnetization transfer (MT) imaging provides additive information to conventional MRI in brain tumors. Methods: MT data of 26 patients with neoplastic and metastatic brain tumors were analyzed at 1.5 T. For the 3 largest tumor groups investigated in this study--glioblastoma multiforme (GBM), meningiomas, and metastases-statistical comparisons were performed. Analyzed MT parameters included the magnetization transfer ratio (MTR) and 4 quantitative MT parameters (qMT): Relaxation times (T1, T2), exchange rate (kf), and macromolecular content (F). Total imaging time of high-resolution whole brain MTR and qMT imaging with balanced steady-state free precession required 9 minutes. Five ROIs were chosen: Contrast-enhancing (T1W-CE), noncontrast-enhancing (T1W-non-CE), proximal hyperintensity (T2W-pSI), distal hyperintensity (T2W-dSI), and a reference (ref). Results: Pathologies showed significant (P < .05) MT changes (MTR and qMT) compared to the reference. The T1W-CE, T1W-non-CE, and T2W-pSI ROIs of GBMs, meningiomas, and metastases showed significant differences in MTR and qMT estimates. Similar MTR with significant different qMT values were observed in several ROIs among different lesions. MT maps (MTR and qMT) indicated changes in tissue appearing unaffected on MRI in most glial tumors. Conclusions: MTR and qMT imaging enables a better differentiation between brain tumors and provides additive information to MRI. [ABSTRACT FROM AUTHOR]

Valproate (VPA) interferes with mitochondrial metabolism causing hyperammonemia, thereby shifting the balance reaction of glutamine (Gln)/glutamate (Glu) toward Gln. In this study we wanted to determine whether metabolic changes could be reproduced in VPA-treated patients with epilepsy and whether the results differed from those known in chronic hepatic encephalopathy (CHE). Seven patients with epilepsy pretreated with VPA and seven healthy volunteers were investigated on a 3T-scanner. We performed proton magnetic resonance spectroscopy (1H-MRS) using a short echo time point-resolved spectroscopy (PRESS) in the parietal and occipital lobe, respectively. Spectral analysis was performed by LCModel, allowing a separation of Glu and Gln at 3T. Absolute values of myo-Inositol (mI), choline (Cho), creatine (Cr), N-acetyl-aspartate (NAA), glutamine (Gln), glutamate (Glu), and the sum of Gln and Glu (Glx) were calculated. In the parietal lobe, mI was significantly decreased in the patients’ group compared to the healthy volunteers. After separation of the signals of Gln and Glu, a significant increase of Gln was observed in the parietal lobe in the patients’ group. No significant differences in the occipital spectra could be observed between the groups. In VPA-treated patients the alteration of the Glu/Gln ratio differs from that in patients with CHE, where Glx is markedly increased because of an increase in Gln. The expected shift from the biochemical balance reaction of Gln/Glu induced by VPA could be reproduced for the parietal lobe. Significantly reduced mI in the parietal lobe of VPA-treated patients most likely reflects an osmolytic compensation for high Gln. [ABSTRACT FROM AUTHOR]