Publications (3)11.15 Total impact
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Article: Correction: multiplexed echo planar imaging for sub-second whole brain FMRI and fast diffusion imaging.
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ABSTRACT: [This corrects the article on p. e15710 in vol. 5.].PLoS ONE 01/2011; 6(9). · 4.09 Impact Factor -
Article: Multiplexed echo planar imaging for sub-second whole brain FMRI and fast diffusion imaging.
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ABSTRACT: Echo planar imaging (EPI) is an MRI technique of particular value to neuroscience, with its use for virtually all functional MRI (fMRI) and diffusion imaging of fiber connections in the human brain. EPI generates a single 2D image in a fraction of a second; however, it requires 2-3 seconds to acquire multi-slice whole brain coverage for fMRI and even longer for diffusion imaging. Here we report on a large reduction in EPI whole brain scan time at 3 and 7 Tesla, without significantly sacrificing spatial resolution, and while gaining functional sensitivity. The multiplexed-EPI (M-EPI) pulse sequence combines two forms of multiplexing: temporal multiplexing (m) utilizing simultaneous echo refocused (SIR) EPI and spatial multiplexing (n) with multibanded RF pulses (MB) to achieve m×n images in an EPI echo train instead of the normal single image. This resulted in an unprecedented reduction in EPI scan time for whole brain fMRI performed at 3 Tesla, permitting TRs of 400 ms and 800 ms compared to a more conventional 2.5 sec TR, and 2-4 times reductions in scan time for HARDI imaging of neuronal fibertracks. The simultaneous SE refocusing of SIR imaging at 7 Tesla advantageously reduced SAR by using fewer RF refocusing pulses and by shifting fat signal out of the image plane so that fat suppression pulses were not required. In preliminary studies of resting state functional networks identified through independent component analysis, the 6-fold higher sampling rate increased the peak functional sensitivity by 60%. The novel M-EPI pulse sequence resulted in a significantly increased temporal resolution for whole brain fMRI, and as such, this new methodology can be used for studying non-stationarity in networks and generally for expanding and enriching the functional information.PLoS ONE 01/2010; 5(12):e15710. · 4.09 Impact Factor -
Article: Hybrid ultrasound MRI for improved cardiac imaging and real-time respiration control.
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ABSTRACT: A hybridized dual-imaging system combining real-time ultrasound imaging and MRI was utilized for cardiac imaging at 1.5 T and 3 T. The ultrasound scanner with a programmable software interface was connected via computer to the MRI scanner. Electronic noise was eliminated with electromagnetic shielding and grounding to the screen room. At 3 T, real-time prospective motion compensation in dynamic cine cardiac imaging was implemented using B-mode ultrasound imaging. The ultrasound technique avoided drawbacks such as signal saturation or steady-state interruption of the MR navigator gating. At 1.5 T, a low-latency real-time feedback to balanced steady state free precision MR imaging was performed in three normal volunteers. Results showed active tracking of the heart during respiratory motion and improvement in time-averaged cardiovascular images. Future studies can fully exploit the potential of the high-frequency position information provided by the ultrasound system for more advanced applications in real-time organ tracking.Magnetic Resonance in Medicine 12/2009; 63(2):290-6. · 2.96 Impact Factor
