Premium
False‐positive analysis of functional MRI during simulated deep brain stimulation: A phantom study
Author(s) -
Liu HoLing,
Chen HsinMei,
Wu YuChien,
Lim SiewNa,
Huang ChihMao,
Hsu YuanYu,
Wai YauYau,
Wu Tony
Publication year - 2008
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.21222
Subject(s) - imaging phantom , echo planar imaging , voxel , nuclear medicine , medicine , magnetic resonance imaging , biomedical engineering , nuclear magnetic resonance , radiology , physics
Purpose To investigate the false‐positive activations/deactivations in functional MRI (fMRI) of deep brain stimulation (DBS) using a phantom. Materials and Methods fMRI experiments were performed on a 1.5T scanner using a single‐shot gradient‐echo echo‐planar imaging (GE‐EPI) sequence (TR/TE/FA = 6000 msec/60 msec/90°) on an agar‐gel phantom inserted with DBS electrodes. During the experimental blocks, two‐second stimuli were delivered during the interscan waiting time (ISWT), which was adjusted by changing the number of slices acquired within the TR (3500 msec with 30 slices and 5160 msec with 10 slices). Data were analyzed using SPM2 software, and the false‐positive voxels were detected with five different P‐value thresholds. Results The number of false‐positive voxels in experimental conditions had no significant differences from those in control conditions with either long or short ISWT, which increased with the P‐value threshold from zero at P < 0.0001 to approximately 40 at P < 0.05. The pattern of increasing number of false‐positive reactions along with P‐value was similar between all conditions. Conclusion False‐positive findings from fMRI with similar experimental design can be well controlled with a statistical threshold of P < 0.001 or tighter. The short ISWT of 3500 msec did not increase false‐positive reactions compared to the long ISWT of 5160 msec. J. Magn. Reson. Imaging 2008;27:1439–1442. © 2008 Wiley‐Liss, Inc.