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Diffusion tensor imaging and T 2 relaxometry of bilateral lumbar nerve roots: feasibility of in‐plane imaging
Author(s) -
Karampinos Dimitrios C.,
Melkus Gerd,
Shepherd Timothy M.,
Banerjee Suchandrima,
Saritas Emine U.,
Shankaranarayanan Ajit,
Hess Christopher P.,
Link Thomas M.,
Dillon William P.,
Majumdar Sharmila
Publication year - 2013
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.2902
Subject(s) - coronal plane , diffusion mri , nerve root , magnetic resonance neurography , fractional anisotropy , medicine , lumbar , magnetic resonance imaging , anatomy , lumbar nerve , spinal nerve , nuclear medicine , nuclear magnetic resonance , radiology , physics , dorsum
Lower back pain is a common problem frequently encountered without specific biomarkers that correlate well with an individual patient's pain generators. MRI quantification of diffusion and T 2 relaxation properties may provide novel insight into the mechanical and inflammatory changes that occur in the lumbosacral nerve roots in patients with lower back pain. Accurate imaging of the spinal nerve roots is difficult because of their small caliber and oblique course in all three planes. Two‐dimensional in‐plane imaging of the lumbosacral nerve roots requires oblique coronal imaging with large field of view (FOV) in both dimensions, resulting in severe geometric distortions using single‐shot echo planar imaging (EPI) techniques. The present work describes initial success using a reduced‐FOV single‐shot spin‐echo EPI acquisition to obtain in‐plane diffusion tensor imaging (DTI) and T 2 mapping of the bilateral lumbar nerve roots at the L4 level of healthy subjects, minimizing partial volume effects, breathing artifacts and geometric distortions. A significant variation in DTI and T 2 mapping metrics is also reported along the course of the normal nerve root. The fractional anisotropy is statistically significantly lower in the dorsal root ganglia (0.287 ± 0.068) than in more distal regions in the spinal nerve (0.402 ± 0.040) ( p < 10 –5 ). The T 2 relaxation value is statistically significantly higher in the dorsal root ganglia (78.0 ± 11.9 ms) than in more distal regions in the spinal nerve (59.5 ± 7.4 ms) ( p < 10 –5 ). The quantification of nerve root DTI and T 2 properties using the proposed methodology may identify the specific site of any degenerative and inflammatory changes along the nerve roots of patients with lower back pain. Copyright © 2012 John Wiley & Sons, Ltd.