Identifying lumbosacral plexus nerve root abnormalities in patients with sciatica using 3T readout-segmented echo-planar diffusion weighted MR neurography

Abstract

Objectives To investigate the accuracy of Diffusion Weighted Imaging (DWI) using the Readout Segmentation of Long Variable Echo-trains (RESOLVE) sequence in detecting lumbosacral nerve abnormalities. Methods Following institutional ethics committee approval, patients with sciatica-type lower limb radicular symptoms (n = 110) were recruited and prospectively scanned using 3T MRI. Additional participants (n = 17) who underwent neurophysiological testing (EMG/NCV), were also prospectively studied. In addition to routine lumbar spine MRI, a DWI-RESOLVE sequence of the lumbosacral plexus was performed. Two radiologists, blinded to the side of patient symptoms, independently evaluated the MR images. The size and signal intensity changes of the nerves were evaluated using ordinal 4-point Likert-scales. Signal-to-noise ratio (SNR), apparent diffusion coefficient (ADC) and size were measured for affected and normal nerves. Inter-observer agreement was determined with kappa statistics; κ. Results In patients who did not undergo EMG/NCV testing (n = 110), the DWI-RESOLVE sequence detected lumbosacral nerve abnormalities that correlated with symptoms in 36.3% (40/110). This is a similar percentage to patients who underwent EMG/NCV testing, which was positive and correlated with symptoms in 41.2% (7/17). Inter-observer agreement for evaluation of lumbosacral nerve abnormalities was excellent and ranged from 0.87 to 0.94. SNR and nerve size measurements demonstrated statistically significant differences for the L5 and S1 nerves (p value < 0.05) for patients who did not undergo EMG/NCV testing. Conclusion The DWI-RESOLVE sequence is a promising new method that may permit accurate detection and localization of lumbar nerve abnormalities in patients with sciatica.

Evaluation of image quality of diffusion weighted readout segmentation of long variable echo-trains MR pulse sequence for lumbosacral nerve imaging at 3T

“…While these characteristics of the readout segmented EPI DWI-RESOLVE sequence provide potential for improvements in image quality through fewer artifacts, reduced signal loss and higher spatial resolution, to our knowledge, these features have not been described for the lumbosacral nerves. Therefore, this study involved the evaluation of the technical quality of 3T DWI-RESOLVE images of a phantom and the lumbosacral nerves of healthy volunteers in preparation for clinical study (26), with opportunities for improving the visibility of lumbosacral nerves and image quality.…”

“…The two regions method was utilized to calculate SNR as this technique was found to be more practical, especially for human subject imaging with sequences that require relatively long acquisition times such as the EPI DWI-RESOLVE (26). While the subtraction method for SNR calculation is reported to be more accurate and robust (40), it is impractical for human subject imaging as it requires each sequence to be acquired twice, increasing the likelihood that signal variations may occur due to patient motion and physiological effects, thereby introducing a potential for differences in SNR values due to these sources of error (41).…”

“…To our knowledge, the application of the EPI DWI-RESOLVE has not been described for the lumbosacral nerves. Therefore, in this study, the DWI-RESOLVE sequence was modified and applied on a phantom to quantitatively and qualitatively establish baseline image quality characteristics on human subjects to evaluate the clarity of visualization of lumbosacral nerves and image quality in preparation for clinical study (26). We present the following article in accordance with the MDAR reporting checklist (available at https://qims.amegroups.com/article/ view/10.21037/qims-22-191/rc).…”