Biomedical subjects

Eric E Sigmund

Publications and source records attributed to Eric E Sigmund.

3 recordsLinked to original sources

PubMed2005

Multiple echo diffusion tensor acquisition technique.

The standard method of diffusion tensor imaging (DTI) involves one diffusion-sensitizing gradient direction per acquired signal. This paper describes an alternative method in which the entire direction set required for calculating the diffusion tensor is captured in a few scans. In this method, a series of radiofrequency (RF) pulses are applied, resulting in a train of spin echoes. A pattern of applied magnetic field gradients between the RF pulses generates a different diffusion weighting in both magnitude and direction for each echo, resulting in a dataset sufficient to determine the tensor. This significantly reduces the time required for a full DTI scan and potentially allows a tradeoff of this time for image quality. In the present work, this method is demonstrated in an anisotropic diffusion phantom (asparagus).

Anisotropy↗

PubMed2005

Rapid T1 measurement via decay-recovery decomposition: applications in fringe field and distributed relaxation experiments.

Spin-lattice relaxation time (T(1)) measurements are often time-consuming due to the need to measure the full equilibrium magnetization with a long wait time. However, any magnetization recovery can be decomposed into pure recovery and pure decay components, the latter of which lends itself to a much simpler and faster extraction of T(1). We demonstrate several pulse sequences that accomplish this decomposition experimentally and illustrate its applications in a steady magnetic field gradient, and in materials possessing a broad distribution of T(1).

Algorithms↗

PubMed2004

Simultaneous measurement of diffusion along multiple directions.

This paper introduces the first NMR approach for simultaneously measuring the full diffusion tensor. Using magnetic field gradients of different directions to generate multiple modulations of nuclear spin magnetization, multiple echoes of different modulations are acquired in a single scan to simultaneously measure diffusion along different directions. The experimental demonstrations were conducted in both isotropic and anisotropic systems. Since the diffusion anisotropy holds structural and dynamical information, this approach may be useful for monitoring liquid crystals and electrolytes in metastable states and for studying fluidity in situ in porous networks and in vivo in biological systems.

Anisotropy↗