Stereoscopic Display of the Peripheral Nerves at the Elbow Region Based on MR Diffusion Tensor Imaging with Multiple Post-Processing Methods.

Abstract

Background:Peripheral nerves at the elbow region are prone to entrapment neuropathies and injuries. To make accurate assessment, clinicians need stereoscopic display of the nerves to observe them at all angles.Objectives:To obtain a stereoscopic display of the peripheral nerves at the elbow region based on magnetic resonance (MR) diffusion tensor imaging (DTI) data using three post-processing methods of volume rendering (VR), maximum intensity projection (MIP), and fiber tractography, and to evaluate the difference and correlation between them.Subjects and Methods:Twenty-four elbows of 12 healthy young volunteers were assessed by 20 encoding diffusion direction MR DTI scans. Images belonging to a single direction (anterior-posterior direction, perpendicular to the nerve) were subjected to VR and MIP reconstruction. All raw DTI data were transferred to the Siemens MR workstation for fiber tractography post-processing. Imaging qualities of fiber tractography and VR/MIP were evaluated by two observers independently based on a custom evaluation scale.Results:Stereoscopic displays of the nerves were obtained in all 24 elbows by VR, MIP, and fiber tractography post-processing methods. The VR/MIP post-processing methods were easier to perform compared to fiber tractography. There was no significant difference among the scores of fiber tracking and VR/MIP reconstruction for single direction. The imaging quality scores of fiber tractography and VR/MIP were significantly correlated based on intraclass correlation coefficient (ICC) analysis (ICC ranged 0.709 - 0.901), which suggested that the scores based on fiber tractography and VR/MIP for the same sample were consistent. Inter- and intraobserver agreements were good to excellent.Conclusion:Stereoscopic displays of the peripheral nerves at the elbow region can be achieved by using VR, MIP, and fiber tracking post-processing methods based on raw DTI images. VR and MIP reconstruction could be used as preview tools before fiber tracking to determine whether the raw images are satisfactory.