- Email: [email protected]
Brain activation mapping of leg movement using fMRI with prospective motion correction
NemoImage
13, Number
6, 2001,
Part 2 of 2 Parts 1 D E al@
METHODS
- ACQUISITION
Brain Activation Mapping of Leg Movement using fMFU with Prospective Motion Correction Michael Erb*, Ernst Hiilsmann*,
Uwe Klose*, Stefan Thesent, Wolfgang Grodd*
*Section Exp. MR of the CNS, Dept. of Neuroradiology,
University of Tiibingen, Germany
TSiemens Medical Systems, MR Applications Development, Erlangen, Germany Introduction: Mapping of brain regions activated during voluntary movements can be problematic especially during movement of the leg or other distant body parts due to me induction of accompanied head motion. Therefore. in most programs retrospective motion correction is applied to the fMR1 data before calculating statistical activation maps. Some groups (l-3) use real-time registration and feedback of motion parameters for an online adjustment of slice positions and orientation. We have applied a new method of a ‘prospective acquisition correction’ (PACE) as described in (1) to determine the quality and stability of activation maps during voluntary leg movements.
Methods: fMRI was performed on a 1.5 T scanner (Siemens Sonata) using a multislice EPI sequence (TE 50 ms, TA 1.8 s, (Y 90”, slice thickness 3 mm, no gap, 128(96)x128 matrix, 16 slices, voxel size 2x2x3 mm3) in 4 subjects. The acquired slab of 192x256~48 mm3 covered motor cortex and cerebellum. For each volume the movement relative to a reference volume was calculated and described by 6 parameters (x-,y-,ztranslation; x-,y-,z-rotation). These values were fed back to the sequence controller to determine the new position for the next acquisition. The activation tasks consisted of moving up and down the whole leg (hip), the lower leg (knee) and the foot (ankle). 80 volumes were acquired in 5 groups altering between 8 scans rest and 8 activation scans with TR of 8s. Each task measurement was performed with and without feedback. We used the SPM99 package (Wellcome Department Figure 1. SPM map of hip movement of Cognitive Neurology, London) for calculation and a: without motion correction correction (including signal adjustment) of residual mob: retrospective motion correction only tion and statistical fMRI activation maps. c: prospective motion correction only Results: d: prospective and retrospective motion correction The movements occurred at a frequency of about 0.3 Hz (hip), 0.5 Hz (knee) and 1 Hz (ankle) and were visually controlled. Motion occured mainly in z direction and around the x-axis with decreasing amplitude between the three tasks. Without motion correction many voxel seemed to be activated (corrected threshold p
.* ”/ ._ _i ‘I ~~~ __--~~~~ ~~~ -~--e.-.l.-”
Discussion: Despite the fact that the frequencies of movements were higher than the frequency of the motion detection, the applied clearly improved the robustness of activation mapping, especially for studies with strong head movements.
PACE
References: 1. Thesen S, Heid 0, Mueller
E. Magn Reson Med 2000, 44:457-465 2. Lee CG, Grimm RC, Manduca A, Felmlee JP, Ehman RL, Rieder 3. Cox RW, Jesmanowicz A, Magn Reson Med.1999, 42:1014-1018
s9
SJ Jack CR. Magn
Reson
Med,
199X. 39:234-243
mode
13, Number
6, 2001,
Part 2 of 2 Parts 1 D E al@
METHODS
- ACQUISITION
Brain Activation Mapping of Leg Movement using fMFU with Prospective Motion Correction Michael Erb*, Ernst Hiilsmann*,
Uwe Klose*, Stefan Thesent, Wolfgang Grodd*
*Section Exp. MR of the CNS, Dept. of Neuroradiology,
University of Tiibingen, Germany
TSiemens Medical Systems, MR Applications Development, Erlangen, Germany Introduction: Mapping of brain regions activated during voluntary movements can be problematic especially during movement of the leg or other distant body parts due to me induction of accompanied head motion. Therefore. in most programs retrospective motion correction is applied to the fMR1 data before calculating statistical activation maps. Some groups (l-3) use real-time registration and feedback of motion parameters for an online adjustment of slice positions and orientation. We have applied a new method of a ‘prospective acquisition correction’ (PACE) as described in (1) to determine the quality and stability of activation maps during voluntary leg movements.
Methods: fMRI was performed on a 1.5 T scanner (Siemens Sonata) using a multislice EPI sequence (TE 50 ms, TA 1.8 s, (Y 90”, slice thickness 3 mm, no gap, 128(96)x128 matrix, 16 slices, voxel size 2x2x3 mm3) in 4 subjects. The acquired slab of 192x256~48 mm3 covered motor cortex and cerebellum. For each volume the movement relative to a reference volume was calculated and described by 6 parameters (x-,y-,ztranslation; x-,y-,z-rotation). These values were fed back to the sequence controller to determine the new position for the next acquisition. The activation tasks consisted of moving up and down the whole leg (hip), the lower leg (knee) and the foot (ankle). 80 volumes were acquired in 5 groups altering between 8 scans rest and 8 activation scans with TR of 8s. Each task measurement was performed with and without feedback. We used the SPM99 package (Wellcome Department Figure 1. SPM map of hip movement of Cognitive Neurology, London) for calculation and a: without motion correction correction (including signal adjustment) of residual mob: retrospective motion correction only tion and statistical fMRI activation maps. c: prospective motion correction only Results: d: prospective and retrospective motion correction The movements occurred at a frequency of about 0.3 Hz (hip), 0.5 Hz (knee) and 1 Hz (ankle) and were visually controlled. Motion occured mainly in z direction and around the x-axis with decreasing amplitude between the three tasks. Without motion correction many voxel seemed to be activated (corrected threshold p
.* ”/ ._ _i ‘I ~~~ __--~~~~ ~~~ -~--e.-.l.-”
Discussion: Despite the fact that the frequencies of movements were higher than the frequency of the motion detection, the applied clearly improved the robustness of activation mapping, especially for studies with strong head movements.
PACE
References: 1. Thesen S, Heid 0, Mueller
E. Magn Reson Med 2000, 44:457-465 2. Lee CG, Grimm RC, Manduca A, Felmlee JP, Ehman RL, Rieder 3. Cox RW, Jesmanowicz A, Magn Reson Med.1999, 42:1014-1018
s9
SJ Jack CR. Magn
Reson
Med,
199X. 39:234-243
mode