Data From: B1 Field inhomogeneity correction for qDESS T2 mapping: application to rapid bilateral knee imaging
Creators
- 1. Stanford University Department of Radiology, Stanford University, Stanford, CA, U.S.A.
Description
Purpose: T2 mapping is a powerful tool for studying osteoarthritis (OA) changes and bilateral imaging may be useful in investigating the role of between-knee asymmetry in OA onset and progression. The quantitative double-echo in steady-state (qDESS) can provide fast simultaneous bilateral knee T2 and high-resolution morphometry for cartilage and meniscus.
The qDESS uses an analytical signal model to compute T2 relaxometry maps, which require knowledge of the flip angle (FA).
In the presence of B1 inhomogeneities, inconsistencies between the nominal and actual FA can affect the accuracy of T2 measurements.
We propose a pixel-wise B1 correction method for qDESS T2 mapping exploiting an auxiliary B1 map to compute the actual FA used in the model.
Methods: The technique was validated in a phantom and in vivo with simultaneous bilateral knee imaging.
T2 measurements of femoral cartilage (FC) of both knees of six healthy participants were repeated longitudinally to investigate the association between T2 variation and B1.
Results: The results showed that applying the B1 correction mitigated T2 variations that were driven by B1 inhomogeneities.
Specifically, T2 left-right symmetry increased following the B1 correction (rc = 0.74 > rc = 0.69). Without the B1 correction, T2 values showed a linear dependence with B1. The linear coefficient decreased using the B1 correction (from 24.3 \(\pm\) 1.6 ms to 4.1 \(\pm\) 1.8) and the correlation was not statistically significant after the application of the Bonferroni correction (p-value > 0.01).
Conclusion: the study showed that B1 correction could mitigate variations driven by the sensitivity of the qDESS T2 mapping method to B1, therefore increasing the sensitivity to detect real biological changes. The proposed method may improve the robustness of bilateral qDESS T2 mapping, allowing for an accurate and more efficient evaluation of OA pathways and pathophysiology through longitudinal and cross-sectional studies.
This repository contains the raw data for reproducing the results reported in the paper. The data are provided in NIFTI format. The repository also contains the MALTAB scripts used to compute B1 maps from the NIFTI data.