A novel and effective technique is described for distortion correction in echo planar imaging (EPI) utilizing the field maps derived from multi-echo gradient-echo images. The distortions from different off-resonance related factors such as field inhomogeneity, eddy current effect, radiofrequency pulse frequency offset, and chemical shift effect can be simultaneously reduced to a great extent. W...

In most diffusion tensor imaging (DTI) studies, images are acquired with either a partial-Fourier or a parallel partial-Fourier echo-planar imaging (EPI) sequence, in order to shorten the echo time and increase the signal-to-noise ratio (SNR). However, eddy currents induced by the diffusion-sensitizing gradients can often lead to a shift of the echo in k-space, resulting in three distinct types...

Introduction: Echo volumar imaging (EVI) is a 3D extension of echo-planar imaging (EPI) that allows data from an entire volume to be acquired following a single excitation. However, only a few studies to date have applied EVI to functional MRI (fMRI) due to its high sensitivity to field-inhomogeneity induced distortions. In this study, we extend two EPI distortion correction techniques to EVI: ...

A novel technique of magnetic resonance (MR) imaging, which combines gradient-echo and spin-echo (GRASE) technique, accomplishes T2-weighted multisection imaging in drastically reduced imaging time, currently 24 times faster than spin-echo imaging. The GRASE technique maintains contrast mechanisms, high spatial resolution, and image quality of spin-echo imaging and is compatible with clinical w...

Most diffusion imaging sequences rely on single-shot echo-planar imaging (EPI) for spatial encoding since it is the fastest acquisition available. However, it is sensitive to chemical-shift artifacts due to the low bandwidth in the phase-encoding direction, making fat suppression necessary. Often, spectral-selective RF pulses followed by gradient spoiling are used to selectively saturate the fa...

Considerable evidence exists to support the hypothesis that the hippocampus and related medial temporal lobe structures are crucial for the encoding and storage of information in long-term memory. Few human imaging studies, however, have successfully shown signal intensity changes in these areas during encoding or retrieval. Using functional magnetic resonance imaging (fMRI), we studied normal ...

Functional magnetic resonance imaging (fMRI) has become a powerful and influential method to non-invasively study neuronal brain activity. For this purpose, the blood oxygenation level-dependent (BOLD) effect is most widely used. T2* weighted echo planar imaging (EPI) is BOLD sensitive and the prevailing fMRI acquisition technique. Here, we present an alternative to its standard Cartesian recor...

PURPOSE A novel phantom for image quality testing for functional magnetic resonance imaging (fMRI) scans is described. METHODS The cylindrical, rotatable, ~4.5L phantom, with eight wedge-shaped compartments, is used to simulate rest and activated states. The compartments contain NiCl2 doped agar gel with alternating concentrations of agar (1.4%, 1.6%) to produce T1 and T2 values approximating...

Echo planar imaging is a form of MRI with short image acquisition times, which permits in utero fetal imaging without motion artefacts. Echo planar imaging has been used to measure accurately fetal organ volume and to assess placental function. Two small animal studies have suggested the possibility of intrauterine growth restriction consequent upon MRI. We thus performed a prospective study of...

BACKGROUND Cerebral blood flow (CBF) quantitation using technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) generally requires assessment of input function by arterial blood sampling, which would be invasive for small animals. We therefore performed chest dynamic planar imaging, instead of arterial blood sampling, to estimate the input function and establish noninvasive quantitation met...