Avneesh Chhabra MD, Presenter: Research Grant, Siemens AG Research Consultant, Siemens AG Research Grant, Integra LifeSciences Holdings Corporation Research Grant, General Electric Company

Majid Chalian MD, Abstract Co-Author: Nothing to Disclose

Alan Belzberg, Abstract Co-Author: Nothing to Disclose

Jaimie Shores MD, Abstract Co-Author: Nothing to Disclose

Gedge D Rosson, Abstract Co-Author: License agreement, Aegeria Soft Tissue LLC

John Eng MD, Abstract Co-Author: Nothing to Disclose

John A. Carrino MD, MPH, Abstract Co-Author: Research Grant, Siemens AG Research Grant, Carestream Health, Inc Research Consultant, General Electric Company

Ulnar neuropathy (UN) is the second most common entrapment neuropathy of the upper extremity, after <most common>. Non-specific, mild T2 hyperintensity on conventional MR neurography (MRN) is common in asymptomatic patients. Diffusion tensor imaging (DTI) enables interrogation of the internal architecture of the peripheral nerves and allows quantitative measurements, such as fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Information is limited about utility of these parameters in UN.

In this HIPPA compliant IRB approved retrospective study, 16 subjects (8 males, 8 females; mean age ± SD of 51 ± 19 years) with UN were studied on 3.0 T MR scanners (Verio, Trio, Siemens, Erlangen, Germany). All cases were evaluated with DTI. Axial T1 and T2 SPAIR anatomic MRN images were matched to DTI (single shot EPI, 12 encoding directions; b-values 0, 800 and 1000 s/mm2). FA and ADC values of the ulnar nerve and in-plane unaffected radial nerve were calculated with free hand drawn ROIs (at least 2 mm2 area on the nerve). Signal intensity (SI) was qualitatively assessed and measured on both nerves and also on an adjacent in-plane vessel on MRN. The Kolmogorov-Smirnov test was used to evaluate the normality of distribution of the continuous variables. Quantitative variables were compared between the ulnar nerve and radial nerve using Wilcoxon rank-sum test.

FA, nerve SI, and nerve/vessel SI ratio were statistically different (p<0.001) between the ulnar nerve and unaffected radial nerve (0.29±0.08, 428±45, and 0.983±0.41 vs. 0.45±0.07, 199±39, and 0.477±0.28, respectively). The ulnar nerves were hyperintense in all cases, while the unaffected radial nerves were also mildly hyperintense in 2/16 cases. There was no statistically significant difference in ADC values between ulnar nerve (1609 ± 402 x 10-3 mm2/s) and radial nerve (1461 ± 225 x 10-3 mm2/s).

DTI quantitative parameter (FA) evaluation may increase specificity of MRN for evaluation of ulnar neuropathy and thus, DTI should be considered for including in MRN protocols.  

The study provides evidence that DTI should be incorporated in the MRN protocol for ulnar neuropathy.

Chhabra, A, Chalian, M, Belzberg, A, Shores, J, Rosson, G, Eng, J, Carrino, J, Diffusion Tensor Imaging of Ulnar Neuropathy: Quantitative Evaluation.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043671.html