Eric E. Sigmund Ph.D., M.S., B.S.
Eric E. Sigmund Ph.D., M.S., B.S.
Assistant Professor
Department of Radiology (RESEARCH)

Research Summary
Diffusion tensor imaging (DTI) is a useful tool for noninvasive neuroanatomy measurement and clinical diagnosis of neurological trauma (e.g. stroke) or disorder (e.g. multiple sclerosis). However, its most common imaging modality, echo-planar imaging, possesses artifacts (susceptibility-induced distortions, N/2 ghosting) that can reduce resolution and limit application. This is particularly true in higher field scanners (3 T, 7 T). Alternative diffusion tensor imaging modalities to EPI are under development. To compensate for the loss of EPI scanning speed, both proposed methods accelerate a different portion of the overall scan beyond the standard approach. In one case, a Gradient-Alternated Steady-state free Precession (GASP) sequence is employed, which uses fast steady state imaging while controlling motion induced artifacts. In a second approach, a Multiple Echo Diffusion Tensor Acqusition Technique (MEDITATE), the required variation of the diffusion sensitization (both magnitude and direction) is compressed to very few scans through the use of multiple echoes. This acceleration of permits slower, less artifact-prone imaging modalities for DTI. Trabecular bone is found in various skeletal areas (wrist, hip, leg, spine) and has a complicated network structure on the 100 micron scale. This structure remodels itself to optimally bear mechanical load. Measuring this structure is crucial to fracture risk determination, e.g. in osteoporosis. Clinical standards use bone density to estimate strength, but structural arrangement is known to play a significant role as well. MR methods are under development to noninvasively probe this structure. One method adapts an approach used in porous media, and employs the local magnetic field gradients generated between bone and marrow to encode structure-specific diffusion contrast. These gradients increase with applied field strength, making high field particularly useful. The information derived (surface-to-volume ratio) can complement density scans to improve fracture risk determination.


Research Information
Research Interests
Diffusion Tensor Imaging (Brain) Non-EPI Diffusion methods Trabecular bone diffusion contrast for new fracture diagnostics