This work describes the basics of diffusion measurement in biological systems. The first portion is dedicated to providing an understandable, classical-mechanical description of the Stejskal ] Tanner pulse sequence to give the reader an intuitive understanding of the measurement. This is followed by a description of the various aspects of water motion in biological systems that should be taken ...

BACKGROUND AND PURPOSE The purpose of this work was to evaluate whether diffusion-weighted MR imaging can be used in differentiating residual or recurrent head and neck tumors from postoperative or postradiation changes. MATERIALS AND METHODS This study included 32 patients clinically suspected for recurrent head and neck tumor after surgery (n=3), radiation therapy (n=13), or both (n=16). Di...

Previous findings have demonstrated the diagnostic usefulness of diffusion-weighted imaging in depicting specific features of a brain abscess. We report a case of a cerebral abscess, which ruptured into the ventricular system, including its findings on both diffusion-weighted images and apparent diffusion coefficient (ADC) maps. Purulent material within the left lateral ventricle, similar to th...

Recent studies in the human visual cortex using diffusion-weighted functional magnetic resonance imaging (fMRI) have suggested that the apparent diffusion coefficient (ADC) decreases, in contrast to earlier studies that consistently reported ADC increases during neuronal activation. The changes, in either case, are hypothesized to provide the ability to improve the spatial specificity of fMRI o...

What is a “diffusion coefficient” or “diffusion tensor” in living tissue, anyway? While the measurement of the self-diffusivity in an NMR tube represents a "gold standard", in complex media particularly in living tissue, water “diffusivity” ceases to have a clear meaning or definition. The apparent diffusion coefficient (ADC) and apparent diffusion tensor (ADT) concepts were introduced to answe...

Measurements of apparent diffusion coefficient (ADC) using magnetic resonance imaging (MRI) have been suggested as potential imaging biomarkers for monitoring tumor response to treatment. However, conventional pulsed-gradient spin echo (PGSE) methods incorporate relatively long diffusion times, and are usually sensitive to changes in cell density and necrosis. Diffusion temporal spectroscopy us...

BACKGROUND AND PURPOSE Although diffusion-weighted MR imaging is a powerful tool for evaluating brain ischemia, histopathologic correlates of temporal diffusion changes in cerebral hypoxia/ischemia have not been extensively examined. Diffusion-weighted MR imaging was used to evaluate the relationship between the time course of apparent diffusion coefficient (ADC) changes and the histopathologic...

BACKGROUND AND PURPOSE Most response criteria for patients with glioblastoma rely on increases in the contrast enhancing abnormality to determine tumor progression. Our aim was to determine retrospectively in patients with glioblastoma whether diffusion restriction can predict the development of new enhancing mass lesions. MATERIALS AND METHODS We reviewed the brain MR imaging scans (includin...

Introduction Acute excitotoxicity causes cytotoxic edema that precedes neuron cell necrosis and apoptosis in neurological diseases. Apparent diffusion coefficient (ADC) decreases early reflecting cytotoxic edema in various brain injuries. Our recent study demonstrated that high-resolution diffusion MRI detected three retinal layers of distinct ADC. In this study, we examined the feasibility of ...

We describe a case demonstrating reversible MR imaging findings, including diffusion-weighted imaging changes in association with metronidazole (Flagyl) toxicity. The diagnosis of metronidazole toxicity was made clinically and supported by the MR imaging findings. Quantitative apparent diffusion coefficient (ADC) maps demonstrated edema with associated increased ADC values within the dentate nu...