One of the major barriers to clinical application of functional magnetic resonance imaging (fMRI) is corruption of the intrinsically small signal by global head motion. This research project therefore addresses a fundamental problem common to all fMRI studies. We accomplished the major goal of our original grant which was to develop, validate, and implement a working prototype system for prospective real-time correction of multi- planar head motion for fMRI using a series of orbital navigator echoes to detect motion. In pursuit of improved artifact reduction in clinical fMRI, we have recently developed two new types of navigator echoes, i) a spherical motion detection navigator which can encode all 6 degrees of rigid body motion in a near-instantaneous snapshot and ii) a shim navigator echo which we will use to correct in real-time, motion-induced first order changes in the B0 field. A major focus of aging and dementia research is earlier diagnosis of Alzheimer's disease (AD). In theory an fMRI examination of declarative memory should be an ideal """"""""stress test"""""""" for impending cognitive impairment, because AD pathology begins in the medial temporal lobe limbic system. Despite its potential clinical utility, relatively little progress has been made in the application of fMRI as a diagnostic tool in AD. In our view a major reason for this is the fact that fMRI studies in clinical subjects are commonly degraded by global head motion artifact. In this renewal grant application we propose the following four aims.
Aim number 1: to develop, validate, and implement a new system for real-time detection and correction of image-to-image global head motion in fMRI using a spherical navigator echo.
Aim number 2: to develop, validate and implement a new technique for real-time first order correction of head motion-induced changes in the B0 field (real-time auto-shimming).
Aim number 3: to test the hypothesis that the real-time motion-artifact reduction techniques developed in Aims number 1 and number 2 will improve the fidelity of fMRI.
Aim number 4: to assess motion corrected fMRI as a diagnostic test for early Alzheimer's disease.
| Machulda, Mary M; Senjem, Matthew L; Weigand, Stephen D et al. (2009) Functional magnetic resonance imaging changes in amnestic and nonamnestic mild cognitive impairment during encoding and recognition tasks. J Int Neuropsychol Soc 15:372-82 |
| Welch, Edward Brian; Manduca, Armando; Grimm, Roger C et al. (2004) Interscan registration using navigator echoes. Magn Reson Med 52:1448-52 |
| Machulda, M M; Ward, H A; Borowski, B et al. (2003) Comparison of memory fMRI response among normal, MCI, and Alzheimer's patients. Neurology 61:500-6 |
| Ward, Heidi A; Riederer, Stephen J; Jack Jr, Clifford R (2002) Real-time autoshimming for echo planar timecourse imaging. Magn Reson Med 48:771-80 |
| Welch, Edward Brian; Manduca, Armando; Grimm, Roger C et al. (2002) Spherical navigator echoes for full 3D rigid body motion measurement in MRI. Magn Reson Med 47:32-41 |
| Machulda, M M; Ward, H A; Cha, R et al. (2001) Functional inferences vary with the method of analysis in fMRI. Neuroimage 14:1122-7 |
