Strategies for improving the detection of fMRI activation in trigeminal pathways with cardiac gating

doi:10.1016/j.neuroimage.2006.02.033

NeuroImage

Volume 31, Issue 4, 15 July 2006, Pages 1506-1512

https://doi.org/10.1016/j.neuroimage.2006.02.033 Get rights and content

Abstract

Functional magnetic resonance imaging (fMRI) has become a powerful tool for studying the normal and diseased human brain. The application of fMRI in detecting neuronal signals in the trigeminal system, however, has been hindered by low detection sensitivity due to activation artifacts caused by cardiac pulse-induced brain and brainstem movement. A variety of cardiac gating techniques have been proposed to overcome this issue, typically by phase locking the sampling to a particular time point during each cardiac cycle. We sought to compare different cardiac gating strategies for trigeminal system fMRI. In the present study, we used tactile stimuli to elicit brainstem and thalamus activation and compared the fMRI results obtained without cardiac gating and with three different cardiac gating strategies: single-echo with TR of 3 or 9 heartbeats (HBs) and dual-echo T2*-mapping EPI (TR = 2 HBs, TE = 21/55 ms). The dual-echo T2* mapping and the single-echo with TR of 2 and 3 HBs cardiac-gated fMRI techniques both increased detection rate of fMRI activation in brainstem. Activation in the brainstem and the thalamus was best detected by cardiac-gated dual-echo EPI.

Section snippets

Introduction and background

Functional imaging of the trigeminal system in humans is important to increase our understanding of its physiological and pathological role in diseases such as migraine and neuropathic pain. It is however more difficult to achieve than imaging of the cortex because of the presence of numerous potential artifacts. Only a few functional studies have examined the trigeminal system, either during headache using positron emission tomography (PET) (Hsieh et al., 1999, Matharu et al., 2004) or during

Materials and methods

Ten right-handed healthy subjects (age: 31.9 ± 5.6 years, mean ± SD; 6 females) were enrolled and gave informed written consent. None of the subjects reported a history of or was suffering from acute or chronic trigeminal or cervical pain. The study protocol was approved by the Institutional Review Board of our institution.

All MRI scans were performed on a Siemens 3-T Trio MR scanner (Siemens Medical Systems, Erlangen, Germany) with an 8-channel head array coil. Each subject was wired to a

Results

The ratios of subjects who showed activation in the ipsilateral principle sensory trigeminal nucleus (PSTN) and ventroposterior medial nucleus (VPM) in the contralateral thalamus are summarized in Table 2. Four out of 10 (40%) ungated time series showed activation in PSTN. The detection rate increased to 70% for the gated single echo (TR = 3 HBs) and to 67% for the second echo (TE2) of dual-echo EPI time series. The detection rate of T2* time series calculated from dual-echo images was 89%, the

Discussion

The present study systematically compared different cardiac gating methods to conventional ungated fMRI in their ability to detect activation in the trigeminal pathway. Brainstem studies clearly require novel approaches: unlike primary sensory fMRI activation, where discussions focus around how to best quantify the robust activation present in nearly every subject, simply finding any activation in these small regions of the moving brain is considered an accomplishment, hence, the strong

Acknowledgments

This work was supported by PHS grants 5P01 NS35611-07, National Center for Research Resources General Clinical Resource Centers Program (M01-RR-01066), NCRR Center for Functional Neuroimaging Technologies (5P41RR014075), Mental Illness and Neuroscience Discovery (MIND) Institute, and Federazione Italiana Sclerosi Multipla (FISM) 2003/B/8. We also want to thank Dr. Nouchine Hadjikhani, Dr. Vitaly Napadow and Dr. Kathleen Hui for the constructive discussions.

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Strategies for improving the detection of fMRI activation in trigeminal pathways with cardiac gating

Abstract

Section snippets

Introduction and background

Materials and methods

Results

Discussion

Acknowledgments

NeuroImage

Comput. Biomed. Res.

NeuroImage

Magn. Reson. Imaging

Magn. Reson. Imaging

Eur. J. Pain

Clin. Neurophysiol.

Simultaneous sampling of event-related BOLD responses in auditory cortex and brainstem

Magn. Reson. Med.

Functional MR imaging of the cervical spinal cord by use of median nerve stimulation and fist clenching

Am. J. Neuroradiol.

Reduction of physiological fluctuations in fMRI using digital filters

Magn. Reson. Med.

Rapid T(1) mapping using multislice echo planar imaging

Magn. Reson. Med.

Cortical and subcortical control of tongue movement in humans: a functional neuroimaging study using fMRI

J. Appl. Physiol.

Somatotopic activation in the human trigeminal pain pathway

J. Neurosci.

Image-based method for retrospective correction of physiological motion effects in fMRI: RETROICOR

Magn. Reson. Med.