T2 Relaxometry of Human Median Nerve

ABSTRACT

This article examines the T2 relaxation characteristics of the median nerve. Knowledge of the T2 relaxation time is essential to optimize clinical magnetic resonance imaging (MRI) protocols and to enhance the visibility of pathophysiological changes in tissues. The T2 relaxation time of the median nerve is short relative to the T2 of other tissues like white and gray matter, for instance, and it decreases with increasing field strength of the MR scanner. A T2 relaxation time of ~50 milliseconds (ms) and ~20 ms were reported at 1.5 T and 7 T, respectively. Detailed measurements at 3.0 T revealed a biexponential decay characterized by two T2 components, at ~30 ms and ~100 ms, with normalized amplitudes of ~80% and ~20%, respectively. These two components possibly result from spatial compartmentation of water into intra-axonal and interaxonal spaces. The ability to assess microanatomical compartments within the median nerve could provide a method to study in vivo biophysical properties of nerves and could offer a means to investigate neurodegenerative diseases.

KEYWORDS

Magnetic resonance imaging - T2 relaxation time - peripheral nervous system - median nerve - in vivo relaxometry

REFERENCES

• 1 Farooki S, Ashman C J, Yu J S, Abduljalil A, Chakeres D. In vivo high-resolution MR imaging of the carpal tunnel at 8.0 Tesla.  Skeletal Radiol. 2002;  31 445-450
• 2 Gambarota G, Veltien A, Klomp D, Van Alfen N, Mulkern R V, Heerschap A. Magnetic resonance imaging and T2 relaxometry of human median nerve at 7 Tesla.  Muscle Nerve. 2007;  36 368-373
• 3 Gambarota G, Mekle R, Mlynárik V, Krueger G, Gruetter R. T1 and T2 relaxation times of human median nerve at 3 Tesla. In: Proceedings of the 15th Annual Meeting of International Society of Magnetic Resonance in Medicine (ISMRM) Berlin, Germany; ISMRM 2007: 2694
• 4 Grant G A, Britz G W, Goodkin R, Jarvik J G, Maravilla K, Kliot M. The utility of magnetic resonance imaging in evaluating peripheral nerve disorders.  Muscle Nerve. 2002;  25 314-331
• 5 Dailey A T, Tsuruda J S, Filler A G, Maravilla K R, Goodkin R, Kliot M. Magnetic resonance neurography of peripheral nerve degeneration and regeneration.  Lancet. 1997;  350 1221-1222
• 6 Chappell K E, Robson M D, Stonebridge-Foster A et al.. Magic angle effects in MR neurography.  AJNR Am J Neuroradiol. 2004;  25 431-440
• 7 Gambarota G, Cairns B E, Berde C B, Mulkern R V. Osmotic effects on the T2 relaxation decay of in vivo muscle.  Magn Reson Med. 2001;  46 592-599
• 8 Does M D, Snyder R E. T2 relaxation of peripheral nerve measured in vivo.  Magn Reson Imaging. 1995;  13 575-580
• 9 Gambarota G, Scheenen T W, Cairns B E, Klomp D W, Heerschap A. Multicomponent T2 relaxation of human median nerve in vivo. In: Proceedings of 20th Annual Meeting of European Society of Magnetic Resonance in Medicine and Biology (ESMRMB) Rotterdam, The Netherlands; MAGMA 2003: S75
• 10 Wansapura J P, Holland S K, Dunn R S, Ball Jr W S. NMR relaxation times in the human brain at 3.0 Tesla.  J Magn Reson Imaging. 1999;  9 531-538
• 11 Michaeli S, Garwood M, Zhu X H et al.. Proton T2 relaxation study of water, N-acetylaspartate, and creatine in human brain using Hahn and Carr-Purcell spin echoes at 4T and 7T.  Magn Reson Med. 2002;  47 629-633
• 12 Bloembergen N, Purcell E M, Pound R V. Relaxation effects in nuclear magnetic resonance absorption.  Physical Rev. 1948;  73 679-712
• 13 Peto S, Gillis P. Fiber-to-field angle dependence of proton nuclear magnetic relaxation in collagen.  Magn Reson Imaging. 1990;  8 705-712
• 14 Skorpil M, Karlsson M, Nordell A. Peripheral nerve diffusion tensor imaging.  Magn Reson Imaging. 2004;  22 743-745
• 15 Meek M F, Stenekes M W, Hoogduin H M, Nicolai J P. In vivo three-dimensional reconstruction of human median nerves by diffusion tensor imaging.  Exp Neurol. 2006;  198 479-482
• 16 Hiltunen J, Suortti T, Arvela S, Seppä M, Joensuu R, Hari R. Diffusion tensor imaging and tractography of distal peripheral nerves at 3 T.  Clin Neurophysiol. 2005;  116 2315-2323
• 17 Kabakci N, Gürses B, Firat Z et al.. Diffusion tensor imaging and tractography of median nerve: normative diffusion values.  AJR Am J Roentgenol. 2007;  189 923-927
• 18 Skorpil M, Engström M, Nordell A. Diffusion-direction-dependent imaging: a novel MRI approach for peripheral nerve imaging.  Magn Reson Imaging. 2007;  25 406-411
• 19 Wolff S D, Balaban R S. Magnetization transfer contrast (MTC) and tissue water proton relaxation in vivo.  Magn Reson Med. 1989;  10 135-144
• 20 Gambarota G, Mekle R, Gruetter R. Magnetization transfer effects in human median nerve at 3 T. In: Proceedings of the 16th Annual Meeting of International Society of Magnetic Resonance in Medicine (ISMRM) Toronto, Canada; ISMRM 2008: 3663
• 21 Gambarota G, Mekle R, Gruetter R. High-resolution MR imaging of the foot: magnetization transfer effects in foot peripheral nerves. In: Proceedings of the 16th Annual Meeting of International Society of Magnetic Resonance in Medicine (ISMRM) Toronto, Canada; ISMRM 2008: 3664
• 22 Dousset V, Grossman R I, Ramer K N et al.. Experimental allergic encephalomyelitis and multiple sclerosis: lesion characterization with magnetization transfer imaging.  Radiology. 1992;  182 483-491
• 23 Gass A, Barker G J, Kidd D et al.. Correlation of magnetization transfer ratio with clinical disability in multiple sclerosis.  Ann Neurol. 1994;  36 62-67