gms | German Medical Science

Kongress Medizin und Gesellschaft 2007

17. bis 21.09.2007, Augsburg

Event-related real-time functional Magnetic Resonance Imaging (erfMRI) at 3T and 7T

Meeting Abstract

  • Tobias Moench - Medical Faculty, Institute for Biometry and Medical Informatics, University of Magdeburg, Magdeburg
  • Maurice Hollmann - Medical Faculty, Institute for Biometry and Medical Informatics, University of Magdeburg, Magdeburg
  • Claus Tempelmann - Medical Faculty, Clinic for Neurology II, University of Magdeburg, Magdeburg
  • Ralf Lützkendorf - Medical Faculty, Institute for Biometry and Medical Informatics, University of Magdeburg, Magdeburg
  • Sebastian Baecke - Medical Faculty, Institute for Biometry and Medical Informatics, University of Magdeburg, Magdeburg
  • Johannes Bernarding - Medical Faculty, Institute for Biometry and Medical Informatics, University of Magdeburg, Magdeburg

Kongress Medizin und Gesellschaft 2007. Augsburg, 17.-21.09.2007. Düsseldorf: German Medical Science GMS Publishing House; 2007. Doc07gmds630

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/gmds2007/07gmds630.shtml

Veröffentlicht: 6. September 2007

© 2007 Moench et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction: New experiments using erfMRI enable self-regulation of brain-activity or optimising learning strategies [1],[2]. However, real-time statistical analysis is usually less powerful than a full General Linear Model and short stimulus durations (event-related stimuli) decreases the BOLD signal. Therefore, higher field strengths such as 3T or 7T are required.

Methods: For online data export a standard EPI-BOLD sequence was modified. Experiment and data analysis were controlled with a custom-made XML-based parameter/experiment description language (EDL) and a MATLAB application (post-processing, statistical analysis, visualization). t-test and correlation-analysis with a double-gamma function were implemented. Results were displayed to the investigator and the volunteer. erfMRI experiments were conducted at 3T and 7T scanners (both Siemens) with 64x64 matrix, TR=2s, TE=29s (3T) or 20s(7T), 31 slices (3T) or 16 slices (7T). Visual stimulation (10 Hz checkerboard), and finger-tapping were measured. Activation/rest blocks (20s/20s) served to localize activated areas. Subsequently, stimulus duration was shortened from 10 sec to 0.1 sec. A constant window as well as a growing window was used to analyse data online..

Results: Visual areas were detectable at a minimum stimulus duration of 500 ms at 7T and 1 sec at 3T. Motor areas were detected at a minimum stimulus duration of 1 sec at 7T and 2 sec at 3T. Mean signal change was 2-3% (1s stimulus duration) for motor activation at 3T, and 5-6% at 7T. For visual areas mean signal change was of 3-4% at 7T and 2-3% at 3T (500ms stimulus

duration).

Conclusion: The results represent the first successful erfMRI 7T with stimulus duration as short as 500 ms. At 7T the activated clusters were more homogeneous and the mean signal change was larger than at 3T which should allow to detect smaller activated clusters.


References

1.
N. Weiskopf et al., Self-regulation of local brain activity using real-time functional magnetic resonance imaging (fMRI). Journal of Physiology, pages 357–373, 2004
2.
Posse et al., A New Approach to Measure Single-Event Related Brain Activity Using Real-Time fMRI: Feasibility of Sensory, Motor, and Higher Cognitive Tasks. - Human Brain Mapping, 12:25-41, 2001