The principles of contrast mechanisms and fast pulse sequences underlying neurological and neuroradiological application of MRI are introduced in this part of a two-part review. In particular, the relaxation time constants T(1), T(2), and T(2) (*) are introduced, along with pulse sequences harnessing their contrast, spin-echo, fast spin echo (FSE), inversion recovery (IR), gradient recalled ech...

BACKGROUND AND PURPOSE We analyzed the temporal and spatial pattern of water diffusion changes during acute subarachnoid hemorrhage (SAH) in rat brain to identify factors contributing to the acute pathophysiology of SAH. METHODS Subarachnoid hemorrhage was remotely induced via perforation of the circle of Willis with an endovascular suture during MR imaging. A fast echo-planar imaging techniq...

PURPOSE The goal of this study was to determine the effect of contrast media on the signal behavior of single-shot echo planar imaging (ssEPI) used for abdominal diffusion imaging. MATERIALS AND METHODS The signal of an ssEPI spin echo sequence in a water phantom with varying concentrations of gadolinium was modeled with Bloch equations and the predicted behavior validated on a phantom at 1.5...

Diffusion MRI is a useful imaging technique with many clinical applications. Many diffusion MRI studies have utilized echo-planar imaging (EPI) acquisition techniques. In this study, we have developed a rapid diffusion-prepared fast imaging with steady-state free precession MRI acquisition for a preclinical 7T scanner providing diffusion-weighted images in less than 500 ms and diffusion tensor ...

BACKGROUND AND PURPOSE The purpose of this work was to test the feasibility of using high angular resolution diffusion imaging (HARDI)-based multitensor tractography to depict motor pathways in patients with brain tumors. MATERIALS AND METHODS Ten patients (6 males and 4 females) with a mean age of 52 years (range, 9-77 years) were scanned using a 1.5T clinical MR unit. Single-shot echo-plana...

In diffusion MRI, simultaneous multi-slice single-shot EPI acquisitions have the potential to increase the number of diffusion directions obtained per unit time, allowing more diffusion encoding in high angular resolution diffusion imaging (HARDI) acquisitions. Nonetheless, unaliasing simultaneously acquired, closely spaced slices with parallel imaging methods can be difficult, leading to high ...

Amyotrophic lateral sclerosis (ALS) is characterized by progressive degeneration of motor neurons. A reliable, noninvasive, and objective imaging method of upper motor neuron involvement is critical for the early diagnosis and monitoring of disease progression in ALS patients. Magnetic resonance diffusion tensor imaging (DTI) has been used to show differences in fractional anisotropy (FA) of wa...