Keizo Tanitame MD, Presenter: Nothing to Disclose

Takako Yamaguchi, Abstract Co-Author: Nothing to Disclose

Yuji Akiyama, Abstract Co-Author: Nothing to Disclose

Miyuki Takasu MD, Abstract Co-Author: Nothing to Disclose

Kazuhide Ochi MD, Abstract Co-Author: Nothing to Disclose

Kazuo Awai MD, Abstract Co-Author: Nothing to Disclose

Hiroshi Fukuda MD, PhD, Abstract Co-Author: Nothing to Disclose

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immune-mediated inflammatory disorder of the peripheral nervous system with loss of the myelin sheaths. The aim of this study was to compare FA values of peripheral nerves in CIDP patients and normal volunteers and to analyze the correlation between the FA values and the results of nerve conduction study in CIDP patients.

We enrolled 10 patients with CIDP and 10 sex and age-matched healthy volunteers. A 3-T MR unit and a quadrature lower extremity coil were used for scanning tibial nerves. Spin-echo based diffusion-weighted echo planar images in the axial plane were acquired; the imaging parameters were TR 3500 ms, TE 93 ms, field of view 200 mm, matrix 192 x 192, slice thickness 5 mm, b value 1000 s/mm2, different diffusion gradient orientations 15, number of excitations 9, slices 7. Color-coded FA maps were generated with manufacturer-supplied software and freehand regions of interest were placed to encompass the tibial nerves on the FA maps. The maximum FA values of tibial nerves were compared in CIDP patients and normal volunteers. For nerve conduction study we examined the symptomatic lower legs of 9 patients. We analyzed the correlation between the maximum FA values and the results of nerve conduction study in CIDP patients.

The maximum FA values could be measured in all volunteers and CIDP patients. The median maximum FA values of tibial nerves in patients and normal volunteers were 0.401 (range 0.316 - 0.510) and 0.530 (range 0.469 - 0.647), respectively. The maximum FA values were significantly lower in CIDP patients than in normal volunteers (p = 0.002). The maximum FA values were strongly correlated with the amplitude of the nerve action potential in 7 patients (p = 0.036); in the other 2 patients, no action potentials were evoked and the maximum FA values were very low (0.316 and 0.351). The maximum FA values were not correlated with nerve conduction velocities in 7 patients (p = 0.790).

Measurement of the maximum FA values of peripheral nerves is feasible and may be a quantitative method for diagnosing CIDP and assessing the disease severity.

Water molecules move along the peripheral nerve fibers and the FA value in demyelinated peripheral nerve is expected to be lower than in normal peripheral nerves.

Tanitame, K, Yamaguchi, T, Akiyama, Y, Takasu, M, Ochi, K, Awai, K, Fukuda, H, Fractional Anisotrophy (FA) Value of Peripheral Nerves at 3.0 T MR Scanning: Feasibility Study and Initial Experience in Patients with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP).  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9000923.html