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Updated: Jul 5, 2026
Deep Brain Stimulation with Simultaneous fMRI in Rodents
Published on: February 15, 2014
False-positive analysis of functional MRI during simulated deep brain stimulation: a phantom study
Ho-Ling Liu1, Hsin-Mei Chen, Yu-Chien Wu
1Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, Taiwan.
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 degrees ) 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.
Insights
This study used fMRI phantom experiments to assess false-positive activations during deep brain stimulation (DBS). Results show that a statistical threshold of P < 0.001 effectively controls false positives without increasing them with shorter interscan waiting times.
Area of Science:
- Neuroimaging
- Medical Physics
Background:
- Functional MRI (fMRI) is crucial for evaluating deep brain stimulation (DBS) effects.
- Understanding and controlling false-positive signals in fMRI is essential for accurate interpretation of DBS-related brain activity.
Purpose of the Study:
- To investigate and quantify false-positive activations/deactivations in fMRI during simulated deep brain stimulation (DBS).
- To evaluate the impact of interscan waiting time (ISWT) on fMRI false-positive rates.
Main Methods:
- fMRI experiments were conducted on an agar-gel phantom with implanted DBS electrodes using a 1.5T scanner.
- Gradient-echo echo-planar imaging (GE-EPI) sequences were employed with varying ISWT (3500 msec and 5160 msec).
- Statistical Parametric Mapping (SPM2) software was used to analyze data and detect false-positive voxels across different P-value thresholds.
Main Results:
- The number of false-positive voxels did not significantly differ between experimental and control conditions for both short and long ISWT.
- False-positive counts increased with less stringent P-value thresholds (e.g., ~40 at P < 0.05 compared to zero at P < 0.0001).
- The observed pattern of increasing false positives with P-value was consistent across all tested conditions.
Conclusions:
- A statistical threshold of P < 0.001 or stricter is recommended to effectively control false-positive findings in fMRI studies with similar designs.
- A shorter ISWT of 3500 msec did not lead to an increase in false-positive fMRI reactions compared to a longer ISWT of 5160 msec.
