Quantitative MR-Neurography at 3.0T: Inter-Scanner Reproducibility

Abstract

BackgroundQuantitative MR-neurography (MRN) is increasingly applied, however, the impact of the MR-scanner on the derived parameters is unknown. Here, we used different 3.0T MR scanners and applied comparable MR-sequences in order to quantify the inter-scanner reproducibility of various MRN parameters of the sciatic nerve.MethodsTen healthy volunteers were prospectively examined at three different 3.0T MR scanners and underwent MRN of their sciatic nerve using comparable imaging protocols including diffusion tensor imaging (DTI) and T2 relaxometry. Subsequently, inter-scanner agreement was assessed for seven different parameters by calculating the intraclass correlation coefficients (ICCs) and the standard error of measurement (SEM).ResultsAssessment of inter-scanner reliability revealed good to excellent agreement for T2 (ICC: 0.846) and the quantitative DTI parameters, such as fractional anisotropy (FA) (ICC: 0.876), whereas moderate agreement was observed for proton spin density (PD) (ICC: 0.51). Analysis of variance identified significant inter-scanner differences for several parameters, such as FA (p < 0.001; p = 0.02), T2 (p < 0.01) and PD (p = 0.02; p < 0.01; p = 0.02). Calculated SEM values were mostly within the range of one standard deviation of the absolute mean values, for example 0.033 for FA, 4.12 ms for T2 and 27.8 for PD.ConclusionThis study quantifies the measurement imprecision for peripheral nerve DTI and T2 relaxometry, which is associated with the use of different MR scanners. The here presented values may serve as an orientation of the possible scanner-associated fluctuations of MRN biomarkers, which can occur under similar conditions.

Multiparametric Quantitative MRI of Peripheral Nerves in the Leg: A Reliability Study

“…In this regard, the ICC between two observations is a commonly used method for evaluating repeatability. 21 In the present study, the lowest ICC values were obtained from MD and RD test-retest reproducibility of the tibial nerve. This low reproducibility of MD and RD of the tibial nerve may relate to the following two reasons.…”

“…The repeatability and multi‐site reproducibility of certain qMRI study is often assessed prior to its clinical application in developing a monitoring biomarker to track the disease progression or the responsiveness to a therapeutic intervention. In this regard, the ICC between two observations is a commonly used method for evaluating repeatability 21 . In the present study, the lowest ICC values were obtained from MD and RD test–retest reproducibility of the tibial nerve.…”

Quantitative magnetic resonance neurography in chronic inflammatory demyelinating polyradiculoneuropathy: A longitudinal study over 6 years

“…For DTI analysis, ROIs from upper and lower extremity nerves were transferred from the T2‐weighted TSE sequence onto the corresponding b 0 ‐image and corrected manually for spatial misalignment, if necessary. Then, maps for the derived DTI scalars FA, radial diffusivity (RD), mean diffusivity (MD), and axial diffusivity (AD) were generated using the OsirixMD plugin DTI map with a noise threshold of 10 arbitrary units (regarding the signal intensity in the b 0 ‐image), as in previous studies on peripheral neuropathies and healthy volunteers 40–42 …”

“…Then, maps for the derived DTI scalars FA, radial diffusivity (RD), mean diffusivity (MD), and axial diffusivity (AD) were generated using the OsirixMD plugin DTI map with a noise threshold of 10 arbitrary units (regarding the signal intensity in the b 0 ‐image), as in previous studies on peripheral neuropathies and healthy volunteers. 40 , 41 , 42 …”

“…Then, maps for the derived DTI scalars FA, radial diffusivity (RD), mean diffusivity (MD), and axial diffusivity (AD) were generated using the OsirixMD plugin DTI map with a noise threshold of 10 arbitrary units (regarding the signal intensity in the b 0 -image), as in previous studies on peripheral neuropathies and healthy volunteers. [40][41][42] The transverse relaxation time T2 and the proton spin density (PSD) were calculated as described previously. 5,43 Briefly, ROIs from the T2-weighted TSE sequence were transferred onto the corresponding slice of the MSE sequence with the echo time TE 20ms .…”