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Erschienen in:
01.07.2015 | Neuro
MR neurography of ulnar nerve entrapment at the cubital tunnel: a diffusion tensor imaging study
Erschienen in: European Radiology | Ausgabe 7/2015
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Objectives
MR neurography, diffusion tensor imaging (DTI) and tractography at 3 Tesla were evaluated for the assessment of patients with ulnar neuropathy at the elbow (UNE).
Methods
Axial T2-weighted and single-shot DTI sequences (16 gradient encoding directions) were acquired, covering the cubital tunnel of 46 patients with clinically and electrodiagnostically confirmed UNE and 20 healthy controls. Cross-sectional area (CSA) was measured at the retrocondylar sulcus and FA and ADC values on each section along the ulnar nerve. Three-dimensional nerve tractography and T2-weighted neurography results were independently assessed by two raters.
Results
Patients showed a significant reduction of ulnar nerve FA values at the retrocondylar sulcus (p = 0.002) and the deep flexor fascia (p = 0.005). At tractography, a complete or partial discontinuity of the ulnar nerve was found in 26/40 (65 %) of patients. Assessment of T2 neurography was most sensitive in detecting UNE (sensitivity, 91 %; specificity, 79 %), followed by tractography (88 %/69 %). CSA and FA measurements were less effective in detecting UNE.
Conclusion
T2-weighted neurography remains the most sensitive MR technique in the imaging evaluation of clinically manifest UNE. DTI-based neurography at 3 Tesla supports the MR imaging assessment of UNE patients by adding quantitative and 3D imaging data.
Key Points
• DTI and tractography support conventional MR neurography in the detection of UNE
• Regionally reduced FA values and discontinuous tractography patterns indicate UNE
• T2-weighted MR neurography remains the imaging gold standard in cases of UNE
• DTI-based ulnar nerve tractography offers additional topographic information in 3D