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90 results on '"Reichenbach, J.R."'

2. Classification of first-episode psychosis using cortical thickness: A large multicenter MRI study

Author

Pigoni, A., Dwyer, D., Squarcina, L., Borgwardt, S., Crespo-Facorro, B., Dazzan, P., Smesny, S., Spaniel, F., Spalletta, G., Sanfelici, R., Antonucci, L.A., Reuf, A., Oeztuerk, Oe.F., Schmidt, A., Ciufolini, S., Schönborn-Harrisberger, F., Langbein, K., Gussew, A., Reichenbach, J.R., Zaytseva, Y., Piras, F., Delvecchio, G., Bellani, M., Ruggeri, M., Lasalvia, A., Tordesillas-Gutiérrez, D., Ortiz, V., Murray, R.M., Reis-Marques, T., Di Forti, M., Koutsouleris, N., and Brambilla, P.

Published
2021
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14. Disturbed glutathione antioxidative defense is associated with structural brain changes in neuroleptic-naïve first-episode psychosis patients

Author

Langbein, K., primary, Hesse, J., additional, Gussew, A., additional, Milleit, B., additional, Lavoie, S., additional, Amminger, G.P., additional, Gaser, C., additional, Wagner, G., additional, Reichenbach, J.R., additional, Hipler, U.-C., additional, Winter, D., additional, and Smesny, S., additional

Published
2018
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15. Cardiac 4D phase-contrast CMR at 9.4 T using self-gated ultra-short echo time (UTE) imaging

Author

Krämer, M., Motaal, A.G., Herrmann, K.H., Löffler, B., Reichenbach, J.R., Strijkers, G.J., Hoerr, V., Krämer, M., Motaal, A.G., Herrmann, K.H., Löffler, B., Reichenbach, J.R., Strijkers, G.J., and Hoerr, V.

Abstract

Background: Time resolved 4D phase contrast (PC) cardiovascular magnetic resonance (CMR) in mice is challenging due to long scan times, small animal ECG-gating and the rapid blood flow and cardiac motion of small rodents. To overcome several of these technical challenges we implemented a retrospectively self-gated 4D PC radial ultra-short echo-time (UTE) acquisition scheme and assessed its performance in healthy mice by comparing the results with those obtained with an ECG-triggered 4D PC fast low angle shot (FLASH) sequence. Methods: Cardiac 4D PC CMR images were acquired at 9.4 T in healthy mice using the proposed self-gated radial center-out UTE acquisition scheme (TE/TR of 0.5 ms/3.1 ms) and a standard Cartesian 4D PC imaging sequence (TE/TR of 2.1 ms/5.0 ms) with a four-point Hadamard flow encoding scheme. To validate the proposed UTE flow imaging technique, experiments on a flow phantom with variable pump rates were performed. Results: The anatomical images and flow velocity maps of the proposed 4D PC UTE technique showed reduced artifacts and an improved SNR (left ventricular cavity (LV): 8.9 ± 2.5, myocardium (MC): 15.7 ± 1.9) compared to those obtained using a typical Cartesian FLASH sequence (LV: 5.6 ± 1.2, MC: 10.1 ± 1.4) that was used as a reference. With both sequences comparable flow velocities were obtained in the flow phantom as well as in the ascending aorta (UTE: 132.8 ± 18.3 cm/s, FLASH: 134.7 ± 13.4 cm/s) and pulmonary artery (UTE: 78.5 ± 15.4 cm/s, FLASH: 86.6 ± 6.2 cm/s) of the animals. Self-gated navigator signals derived from information of the oversampled k-space center were successfully extracted for all animals with a higher gating efficiency of time spent on acquiring gated data versus total measurement time (UTE: 61.8 ± 11.5%, FLASH: 48.5 ± 4.9%). Conclusions: The proposed self-gated 4D PC UTE sequence enables robust and accurate flow velocity mapping of the mouse heart in vivo at high magnetic fields. At the same time SNR, gating eff

Published
2017

18. Accuracy and reproducibility of a novel semi-automatic segmentation technique for MR volumetry of the pituitary gland

Author

Renz, D.M., Hahn, H.K., Schmidt, P., Rexilius, J., Lentschig, M., Pfeil, A., Sauner, D., Fitzek, C., Mentzel, H.-J., Kaiser, W.A., Reichenbach, J.R., Böttcher, J., and Publica

Abstract

Introduction: Although several reports about volumetric determination of the pituitary gland exist, volumetries have been solely performed by indirect measurements or manual tracing on the gland's boundaries. The purpose of this study was to evaluate the accuracy and reproducibility of a novel semi-automatic MR-based segmentation technique. Methods: In an initial technical investigation, T1-weighted 3D native magnetised prepared rapid gradient echo sequences (1.5 T) with 1 mm isotropic voxel size achieved high reliability and were utilised in different in vitro and in vivo studies. The computer-assisted segmentation technique was based on an interactive watershed transform after resampling and gradient computation. Volumetry was performed by three observers with different software and neuroradiologic experiences, evaluating phantoms of known volume (0.3, 0.9 and 1.62 ml) and healthy subjects (26 to 38 years; overall 135 volumetries). Results: High accuracy of the volume try was shown by phantom analysis; measurement errors were 0.05). Conclusion: The analysed semi-automatic MR volumetry of the pituitary gland is a valid, reliable and fast technique. Possible clinical applications are hyperplasia or atrophy of the gland in pathological circumstances either by a single assessment or by monitoring in follow-up studies.

Published
2011

19. Combined spiroergometry and 31P-MRS of human calf muscle during high-intensity exercise.

Author

Moll, K., Gussew, A., Hein, C., Stutzig, N., and Reichenbach, J.R.

Abstract

Simultaneous measurements of pulmonary oxygen consumption ( VO2), carbon dioxide exhalation ( VCO2) and phosphorus magnetic resonance spectroscopy (31P-MRS) are valuable in physiological studies to evaluate muscle metabolism during specific loads. Therefore, the aim of this study was to adapt a commercially available spirometric device to enable measurements of VO2 and VCO2 whilst simultaneously performing 31P-MRS at 3 T. Volunteers performed intense plantar flexion of their right calf muscle inside the MR scanner against a pneumatic MR-compatible pedal ergometer. The use of a non-magnetic pneumotachograph and extension of the sampling line from 3 m to 5 m to place the spirometric device outside the MR scanner room did not affect adversely the measurements of VO2 and VCO2. Response and delay times increased, on average, by at most 0.05 s and 0.79 s, respectively. Overall, we were able to demonstrate a feasible ventilation response ( VO2 = 1.05 ± 0.31 L/min; VCO2 = 1.11 ± 0.33 L/min) during the exercise of a single calf muscle, as well as a good correlation between local energy metabolism and muscular acidification ( τPCr fast and pH; R2 = 0.73, p < 0.005) and global respiration ( τPCr fast and VO2; R2 = 0.55, p = 0.01). This provides improved insights into aerobic and anaerobic energy supply during strong muscular performances. [ABSTRACT FROM AUTHOR]

Published
2017
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20. Effect of Age on MRI Phase Behavior in the Subcortical Deep Gray Matter of Healthy Individuals

Author

Hagemeier, J., primary, Dwyer, M.G., additional, Bergsland, N., additional, Schweser, F., additional, Magnano, C.R., additional, Heininen-Brown, M., additional, Ramasamy, D.P., additional, Carl, E., additional, Kennedy, C., additional, Melia, R., additional, Polak, P., additional, Deistung, A., additional, Geurts, J.J.G., additional, Reichenbach, J.R., additional, and Zivadinov, R., additional

Published
2013
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42. 31P-MR spectroscopy in children and adolescents with a familial risk of schizophrenia.

Author

Rzanny, R., Klemm, S., Reichenbach, J.R., Pfleiderer, S.O.R., Schmidt, B., Volz, H.-P., Blanz, B., and Kaiser, W.A.

Subjects
SCHIZOPHRENIA, PSYCHOSES, PATHOLOGICAL psychology, MAGNETIC resonance imaging, DISEASES in adults, JUVENILE diseases, NEUROBEHAVIORAL disorders
Abstract

Based on a previous report [9] on alterations of membrane phosphorus metabolism in asymptomatic family members of schizophrenic patients, the aim of the present study was to extend and improve the evaluation and data processing of 31P spectroscopic data obtained from a larger study population by including an analysis of the broad spectral component (BC) of membrane phospholipids (PL). Eighteen children and siblings of patients with schizophrenia and a gender- and age-matched control group of 18 healthy subjects without familial schizophrenia were investigated with phosphorus magnetic resonance spectroscopy (31P-MRS) by using image selected in vivo spectroscopy (ISIS) in the dorsolateral prefrontal regions (DLPFR) of the brain. Spectral analysis was performed by using both the full and truncated FID to estimate metabolic peak ratios of different 31P metabolites and the intensity and linewidth of the broad component. A significantly higher PDE level (p<0.01) and increased linewidth of the PDE components were observed for the high-risk group compared with the control group (p=0.02). No significant differences were observed for PME as well as for other 31P-metabolites. No differences were observed between the left and right hemispheres for different normalised 31P-metabolic levels. Decreased intensities (p=0.03) and smaller linewidths (p=0.01) were obtained for the broad component in the high-risk group. Impairments of membrane metabolism that are typical for schizophrenic patients are partially observed in adolescent asymptomatic family members of schizophrenics, including increased levels of low molecular PDE compounds indicating increased membrane degradation processes, no changes for PME, and decreased intensities and linewidths of the BC indicating changes in the composition and fluidity of membrane phospholipids. Despite limitations to completely suppress fast-relaxing components by dismissing initial FID data points, the spectroscopic results indicate additional changes in the membrane metabolism of high-risk subjects beyond changes of synthesis and degradation. [ABSTRACT FROM AUTHOR]

Published
2003
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46. Visualisierung der symmetrischen Stammganglienverkalkung mittels räumlich hochaufgelöster suszeptibilitätsgewichteter MR-Bildgebung

Author

Böttcher, J., Sauner, D., Jentsch, A., Mentzel, H.-J., Becker, H., Reichenbach, J.R., and Kaiser, W.A.

Abstract

Zusammenfassung Neben den häufigen idiopathischen Stammganglienverkalkungen mit eher geringer Ausprägung wird insbesondere bei einer Alteration des Kalzium- und Phosphatstoffwechsels in Verbindung mit einer Dysfunktion der Nebenschilddrüsen das seltene morphologische Vollbild eines M. Fahr mit bilateralen Verkalkungen der Basalganglien, des Thalamus, des Nucleus dentatus sowie des Marklagers der Großhirnhemisphären diagnostiziert. Die morphologische Diagnosestellung eines M. Fahr erfolgt durch Abklärung mittels CT und MRT, wobei die CT eine Quantifizierung und Detektion von intrazerebralen Verkalkungen mit hoher Sensitivität erlaubt. Die MRT gewinnt bei einer klinisch-neurologischen Manifestation des M. Fahr zunehmend an Bedeutung, um eine anderweitige, nicht mit den intrazerebralen Verkalkungen in Zusammenhang stehende Genese einer klinisch-neurologischen Symptomatik auszuschließen. Die bisher verwendeten MR-Sequenzen ermöglichen nur eine limitierte Detektion der intrakraniellen Kalzifikationen und sind hinsichtlich der Bildgebung durch differierende Signalveränderungen in Abhängigkeit vom Krankheitsstadium, hinsichtlich von Unterschieden im Kalziummetabolismus und in der Zusammensetzung der Kalzifikationen gekennzeichnet. Mit Hilfe einer neuen, räumlich hochaufgelösten, suszeptibilitätsgewichteten MR-Sequenz gelingt die detaillierte Visualisierung intrazerebraler Verkalkungen, welche anhand eines Patienten mit dem Vollbild eines M. Fahr dokumentiert wird. In Ergänzung dazu werden ein Überblick hinsichtlich der für die Diagnosestellung eines M. Fahr relevanten diagnostischen Methoden vermittelt und klinische Aspekte ergänzend diskutiert.

Published
2004
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50. Simultaneous surface electromyography (SEMG) and <F>31P</F>-MR spectroscopy measurements of the lumbar back muscle during isometric exercise

Author

Rzanny, R., Grassme, R., Reichenbach, J.R., Rottenbach, M., Petrovitch, A., Kaiser, W.A., and Scholle, H.C.

Subjects
*ELECTROMYOGRAPHY, *ISOMETRIC exercise, *MUSCLE contraction
Abstract

The aim of this study was to demonstrate the feasibility of simultaneous surface electromyography (SEMG) and 31P-MR spectroscopy (31P-MRS) measurements on the back muscle of volunteers during the performance of an isometric exercise. Six volunteers (three male, three female) performed a modified Biering-So¨rensen test inside a 1.5 T MR scanner while simultaneously recording SEMG signals. A surface coil was used for 31P-MRS with a CSI sequence. Spectra were collected with a voxel resolution of 40 mm×40 mm×100 mm and a temporal resolution of 30 s during periods of rest, sustained muscle contraction and recovery. The duration of muscle contraction was 150 s. SEMG analysis yielded a decrease of the mean SEMG frequency of approximately 20%. The SEMG amplitudes were constant or increased up to approximately 150% during exercise. 31P-MRS showed a maximum decrease of the phosphocreatine (PCr) amplitude down to approximately 32% of its initial value. Simultaneously, a doubling of the inorganic phosphate (Pi) signal was observed. The present study demonstrates that simultaneous SEMG and 31P-MRS measurements of the back muscle are feasible during isometric exercises. [Copyright &y& Elsevier]

Published
2004
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