An algorithm is described for reducing ghost artifacts in echo planar imaging (EPI) using phase corrections derived from images reconstructed using only even or odd k-space lines. The N/2 ghost, that arises principally from time-reversal of alternate k-space lines, was significantly reduced by this algorithm without the need for a calibration scan. In images obtained in eight subjects undergoin...

Electrophysiological studies suggest sensitivity of the prefrontal cortex to changes in the probability of an event. The purpose of this study was to determine if subregions of the prefrontal cortex respond differentially to changes in target probabilities using functional magnetic resonance imaging (fMRI). Ten right-handed adults were scanned using a gradient-echo, echo planar imaging sequence...

The Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) method for magnetic resonance imaging data acquisition and reconstruction has the highly desirable property of being able to correct for motion during the scan, making it especially useful for imaging pediatric or uncooperative patients and diffusion imaging. This method nominally supports a circular fi...

Determination of neurological pathology in white matter disease can be made in a semiquantitative way from T(1)- or T(2)-weighted images. A higher level of quantification based on measured T(1) or T(2) values has been either limited to specific regions of interest or to low-resolution maps. Higher-resolution T(1) maps have proved difficult to obtain due to the excessively long scan times requir...

Recent studies have described some of the new opportunities that have arisen within the context of ultrafast two-dimensional imaging with the advent of spatiotemporal encoding methods. This article explores the potential of integrating these non-Fourier, single-scan, two-dimensional MRI principles, with multi-slice and phase-encoding schemes acting along a third dimension. In unison, these comb...

UNLABELLED Planar 131I scintigraphy is routinely used to detect radioiodine-avid metastases of differentiated thyroid carcinoma (DTC). However, the modality has limitations, such as low sensitivity and lack of anatomic landmarks. We investigated whether SPECT with integrated low-dose CT may have additional value over planar imaging in detecting residue and metastases in DTC patients. METHODS ...

Periodically rotated overlapping parallel lines with enhanced reconstruction-echo-planar imaging (PROPELLER-EPI) is a multishot technique that samples k-space by acquisition of narrow blades, which are subsequently rotated until the entire k-space is filled. It has the unique advantage that the center of k-space, and thus the area containing the majority of functional MRI signal changes, is sam...

In diffusion tensor imaging (DTI) an effective diffusion tensor in each voxel is measured by using a set of diffusion-weighted images (DWIs) in which diffusion gradients are applied in a multiplicity of oblique directions. However, to estimate the diffusion tensor accurately, one must account for the effects of all imaging and diffusion gradient pulses on each signal echo, which are embodied in...

Interleaved echo-planar imaging (EPI) is an ultrafast imaging technique important for applications that require high time resolution or short total acquisition times. Unfortunately, EPI is prone to significant ghosting artifacts, resulting primarily from system time delays that cause data matrix misregistration. In this work, it is shown mathematically and experimentally that system time delays...

Prospective motion correction methods using an optical system, diffusion-weighted prospective acquisition correction, or a free induction decay navigator have recently been applied to correct for motion in diffusion tensor imaging. These methods have some limitations and drawbacks. This article describes a novel technique using a three-dimensional-echo planar imaging navigator, of which the con...