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Focal Epileptiform Activity in the Brain: Detection with Spike-related Functional MR Imaging—Preliminary Results¹

¹ From the Institute of Clinical Radiology (L.J., A.H., S.B., V.S., J.W., M.R.) and Department of Neurology (K.J.W., S.N.), University of Munich, Klinikum Grosshadern, Marchioninistrasse 15, 81366 Munich, Germany. Received January 24, 2001; revision requested March 21; revision received September 7; accepted October 16. Address correspondence to L.J. (e-mail: jaeger@ikra.med.uni-muenchen.de).

View larger version (135K): [in a new window]   Figure 1a. Patient 3. (a) EEG recording (montage to a common reference of several electrodes) acquired inside the MR imager as a baseline (off state). Artifacts due to the echo-planar MR imaging sequence (short arrow) (repetition time msec/echo time msec of 163,000/64, 5-mm section thickness, 128 x 64 matrix, 210 x 280-mm field of view) disturb the EEG recording (long arrow), which is unreadable. (b) Postprocessed EEG recording of a. All artifacts due to the simultaneous performance of the echo-planar MR imaging sequence are eliminated, and the final EEG recording is of diagnostic quality. During baseline acquisition, spikes (arrowheads) and slow wave complexes (arrows) are clearly detected; therefore, these baseline data were discarded.

View larger version (53K): [in a new window]   Figure 1b. Patient 3. (a) EEG recording (montage to a common reference of several electrodes) acquired inside the MR imager as a baseline (off state). Artifacts due to the echo-planar MR imaging sequence (short arrow) (repetition time msec/echo time msec of 163,000/64, 5-mm section thickness, 128 x 64 matrix, 210 x 280-mm field of view) disturb the EEG recording (long arrow), which is unreadable. (b) Postprocessed EEG recording of a. All artifacts due to the simultaneous performance of the echo-planar MR imaging sequence are eliminated, and the final EEG recording is of diagnostic quality. During baseline acquisition, spikes (arrowheads) and slow wave complexes (arrows) are clearly detected; therefore, these baseline data were discarded.

View larger version (77K): [in a new window]   Figure 2a. (a) EEG recording (montage to a common reference of several electrodes) acquired inside the MR imager. Spikes (long arrows) are hidden by ballistocardiographic contamination of the EEG recording (small arrowheads). In one case (*), the amplitude of the spike is too small to be differentiated from the ballistocardiographic contamination of the EEG recording. Under the bottom row of the EEG recording, a simultaneous electrocardiographic recording is shown with typical PQRST complex (short arrow). Acquisition of the spike-related BOLD data was started approximately 2.5 seconds after the spike event in the EEG recording, which is indicated by artifacts due to the echo-planar MR imaging sequence (large arrowhead). (b) Fully postprocessed EEG recording of a (montage to a common reference of several electrodes) without ballistocardiographic contamination and without artifacts due to the echo-planar MR imaging sequence. The EEG recording is of diagnostic quality. Single spikes (long arrows) are now clearly detected, including the one (*) that was not clearly detectable in a. Under the bottom row of the EEG recording, the simultaneously acquired electrocardiographic recording shows the PQRST complex of the recorded EEG (short arrow).

View larger version (47K): [in a new window]   Figure 2b. (a) EEG recording (montage to a common reference of several electrodes) acquired inside the MR imager. Spikes (long arrows) are hidden by ballistocardiographic contamination of the EEG recording (small arrowheads). In one case (*), the amplitude of the spike is too small to be differentiated from the ballistocardiographic contamination of the EEG recording. Under the bottom row of the EEG recording, a simultaneous electrocardiographic recording is shown with typical PQRST complex (short arrow). Acquisition of the spike-related BOLD data was started approximately 2.5 seconds after the spike event in the EEG recording, which is indicated by artifacts due to the echo-planar MR imaging sequence (large arrowhead). (b) Fully postprocessed EEG recording of a (montage to a common reference of several electrodes) without ballistocardiographic contamination and without artifacts due to the echo-planar MR imaging sequence. The EEG recording is of diagnostic quality. Single spikes (long arrows) are now clearly detected, including the one (*) that was not clearly detectable in a. Under the bottom row of the EEG recording, the simultaneously acquired electrocardiographic recording shows the PQRST complex of the recorded EEG (short arrow).

View larger version (74K): [in a new window]   Figure 3a. Patient 5. (a) Amplitude map of the postprocessed EEG recording. Both electrodes with dark red color (arrow) indicate the location of strong spike activity in the left temporal lobe during spike-related functional MR imaging. (b) Superimposed clustered (P .001) BOLD functional MR imaging data on coronal reformatted T1-weighted magnetization-prepared rapid gradient-echo image acquired in the evaluation of measurements 3-7. Colored pixels (arrow) indicate the volume of activation due to spike activity in the left temporal lobe. (c) The time course analysis of the BOLD functional MR imaging data shows the change of signal intensity due to spike activity in the left temporal lobe. This area includes eight voxels in the both the x and y axes. The highest signal intensity increase is found in the center (large solid arrow), which correlates with the ideal reference function (arrowhead) of the paradigm timing. The signal intensity decreases (open arrow) to the periphery of the activated volume. Regions without activation (small solid arrow) have signal intensity at baseline level and do not show any signal intensity change due to inflow or saturation phenomena.

View larger version (157K): [in a new window]   Figure 3b. Patient 5. (a) Amplitude map of the postprocessed EEG recording. Both electrodes with dark red color (arrow) indicate the location of strong spike activity in the left temporal lobe during spike-related functional MR imaging. (b) Superimposed clustered (P .001) BOLD functional MR imaging data on coronal reformatted T1-weighted magnetization-prepared rapid gradient-echo image acquired in the evaluation of measurements 3-7. Colored pixels (arrow) indicate the volume of activation due to spike activity in the left temporal lobe. (c) The time course analysis of the BOLD functional MR imaging data shows the change of signal intensity due to spike activity in the left temporal lobe. This area includes eight voxels in the both the x and y axes. The highest signal intensity increase is found in the center (large solid arrow), which correlates with the ideal reference function (arrowhead) of the paradigm timing. The signal intensity decreases (open arrow) to the periphery of the activated volume. Regions without activation (small solid arrow) have signal intensity at baseline level and do not show any signal intensity change due to inflow or saturation phenomena.

View larger version (136K): [in a new window]   Figure 3c. Patient 5. (a) Amplitude map of the postprocessed EEG recording. Both electrodes with dark red color (arrow) indicate the location of strong spike activity in the left temporal lobe during spike-related functional MR imaging. (b) Superimposed clustered (P .001) BOLD functional MR imaging data on coronal reformatted T1-weighted magnetization-prepared rapid gradient-echo image acquired in the evaluation of measurements 3-7. Colored pixels (arrow) indicate the volume of activation due to spike activity in the left temporal lobe. (c) The time course analysis of the BOLD functional MR imaging data shows the change of signal intensity due to spike activity in the left temporal lobe. This area includes eight voxels in the both the x and y axes. The highest signal intensity increase is found in the center (large solid arrow), which correlates with the ideal reference function (arrowhead) of the paradigm timing. The signal intensity decreases (open arrow) to the periphery of the activated volume. Regions without activation (small solid arrow) have signal intensity at baseline level and do not show any signal intensity change due to inflow or saturation phenomena.

View larger version (15K): [in a new window]   Figure 4. Time course of mean signal intensity in the volume of activation for all six functional MR imaging examinations. The time course of mean signal intensity due to spike-related activation () is shown in relation to that during periods of time without spikes (*). Time points for measurements 3-10 are positioned in the middle of each measurement. The strongest increase of signal intensity was found between 6 and 7 seconds after spike detection. After about 18 seconds, signal intensity due to spikes reached nearly baseline level, which represents the state of rest.