Multicenter reproducibility study of diffusion MRI and fiber tractography of the lumbosacral nerves

Abstract

BackgroundDiffusion tensor imaging (DTI) has been applied in the lumbar and sacral nerves in vivo, but information about the reproducibility of this method is needed before DTI can be used reliably in clinical practice across centers.PurposeIn this multicenter study the reproducibility of DTI of the lumbosacral nerves in healthy volunteers was investigated.Study TypeProspective control series.SubjectsTwenty healthy subjects.Field Strength/Sequence3T MRI. 3D turbo spin echo, and 3.0 mm isotropic DTI scan.AssessmentThe DTI scan was performed three times (twice in the same session, intrascan reproducibility, and once after an hour, interscan reproducibility). At site 2, 1 week later, the protocol was repeated (interweek reproducibility). Fiber tractography (FT) of the lumbar and sacral nerves (L3–S2) was performed to obtain values for fractional anisotropy, mean, axial, and radial diffusivity.Statistical TestsReproducibility was determined using the intraclass correlation coefficient (ICC), and power calculations were performed.ResultsFT was successful and reproducible in all datasets. ICCs for all diffusion parameters were high for intrascan (ranging from 0.70–0.85), intermediate for interscan (ranging from 0.61–0.73), and interweek reliability (ranging from 0.58–0.62). There were small but significant differences between the interweek diffusivity values (P < 0.0005). Depending on the effect size, nerve location, and parameter of interest, power calculations showed that sample sizes between 10 and 232 subjects are needed for cross‐sectional studies.Data ConclusionWe found that DTI and FT of the lumbosacral nerves have intermediate to high reproducibility within and between scans. Based on these results, 10–58 subjects are needed to find a 10% change in parameters in cross‐sectional studies of the lumbar and sacral nerves. The small significant differences of the interweek comparison suggest that results from longitudinal studies need to be interpreted carefully, since small differences may also be caused by factors other than disease progression or therapeutic effects. Level of Evidence: 1 Technical Efficacy: Stage 2J. Magn. Reson. Imaging 2018;48:951–963.

Comparing multiband and singleband EPI in NODDI at 3 T: what are the implications for reproducibility and study sample sizes?

“…When comparing the data acquired with the same multiband factor, we found that NODDI parameters, particularly NDI and ODI, are highly reproducible between subjects and visits, while the parameter that showed the worst reproducibility is FISO. Both NDI and ODI exhibited moderate to high withinsubject reproducibility across the sessions for both SB and MB data, with CoV falling within an acceptable range for all regions (CoV < 2.5%), comparable to those obtained in similar studies for DTI parameters [40,41]. This suggests their potential to be used for exploring individual differences and potentially for clinical applications.…”

Denoising of diffusion MRI improves peripheral nerve conspicuity and reproducibility

“…Diffusion MRI (dMRI) is a noninvasive MR technique that can provide objective, quantitative measurements that reflect microstructural nerve integrity . dMRI is based on the naturally occurring Brownian motion of water molecules.…”

“…1 Diffusion MRI (dMRI) is a noninvasive MR technique that can provide objective, quantitative measurements that reflect microstructural nerve integrity. [4][5][6][7] dMRI is based on the naturally occurring Brownian motion of water molecules. The highly organized microstructure of a nerve's axon bundles directionally restricts diffusion (anisotropy), in comparison to an unconstrained space where water molecules freely diffuse in all directions (isotropy).…”

Magnetic resonance tractography of the lumbosacral plexus

“…Previous MR tractography studies of the lumbosacral plexus used several regions of interest along the nerve pathway and fiber tracking was performed with the FA threshold. [ 29 – 31 ] However, due to the direct proximity of skeletal muscles and peripheral nerves and the similar FA values of both tissues, [ 17 , 18 , 32 ] there is a high contamination risk from muscle fibers when MR tractography of the LSP bundles is performed. It also relies on spatial resolution and algorithm type that separation of 2 structures becomes difficult.…”