Dataset Information

Super-resolution of sodium images from simultaneous ¹ H MRF/²³ Na MRI acquisition.

ABSTRACT: In this work, we introduce a super-resolution method that generates a high-resolution (HR) sodium (²³ Na) image from simultaneously acquired low-resolution (LR) ²³ Na density-weighted MRI and HR proton density, T₁ , and T₂ maps from proton (¹ H) MR fingerprinting in the brain at 7 T. The core of our method is a partial least squares regression between the HR (¹ H) images and the LR (²³ Na) image. An iterative loop and deconvolution with the point spread function of each acquired image were included in the algorithm to generate a final HR ²³ Na image without losing features from the LR ²³ Na image. The method was applied to simultaneously acquired HR proton and LR sodium data with in-plane resolution ratios between sodium and proton data of 3.8 and 1.9 and the same slice thickness. Four volunteers were scanned to evaluate the method's performance. For the data with a resolution ratio of 3.8, the mean absolute difference between the generated and ground truth HR ²³ Na images was in the range of 1.5%-7.2% of the ground truth with a multiscale structural similarity index (M-SSIM) of 0.93 ± 0.03. For the data with a resolution ratio of 1.9, the mean absolute difference was in the range of 4.8%-6.3% with an M-SSIM of 0.95 ± 0.01.

SUBMITTER: Rodriguez GG

PROVIDER: S-EPMC10527031 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Publications

Super-resolution of sodium images from simultaneous 1 H MRF/23 Na MRI acquisition.

Rodriguez Gonzalo G GG Yu Zidan Z Shaykevich Sarah S O'Donnell Lauren F LF Aguilera Liz L Cloos Martijn A MA Madelin Guillaume G

NMR in biomedicine 20230518 10

In this work, we introduce a super-resolution method that generates a high-resolution (HR) sodium (23 Na) image from simultaneously acquired low-resolution (LR) 23 Na density-weighted MRI and HR proton density, T1 , and T2 maps from proton (1 H) MR fingerprinting in the brain at 7 T. The core of our method is a partial least squares regression between the HR (1 H) images and the LR (23 Na) image. An iterative loop and d ...[more]

PMID: 37186038

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Project description:Sodium is crucial for the maintenance of cell physiology, and its regulation of the sodium-potassium pump has implications for various neurological conditions. The distribution of sodium concentrations in tissue can be quantitatively evaluated by means of sodium MRI (23 Na-MRI). Despite its usefulness in diagnosing particular disease conditions, tissue sodium concentration (TSC) estimated from 23 Na-MRI can be strongly biased by partial volume effects (PVEs) that are induced by broad point spread functions (PSFs) as well as tissue fraction effects. In this work, we aimed to propose a robust voxel-wise partial volume correction (PVC) method for 23 Na-MRI. The method is based on a linear regression (LR) approach to correct for tissue fraction effects, but it utilizes a 3D kernel combined with a modified least trimmed square (3D-mLTS) method in order to minimize regression-induced inherent smoothing effects. We acquired 23 Na-MRI data with conventional Cartesian sampling at 7 T, and spill-over effects due to the PSF were considered prior to correcting for tissue fraction effects using 3D-mLTS. In the simulation, we found that the TSCs of gray matter (GM) and white matter (WM) were underestimated by 20% and 11% respectively without correcting tissue fraction effects, but the differences between ground truth and PVE-corrected data after the PVC using the 3D-mLTS method were only approximately 0.6% and 0.4% for GM and WM, respectively. The capability of the 3D-mLTS method was further demonstrated with in vivo 23 Na-MRI data, showing significantly lower regression errors (ie root mean squared error) as compared with conventional LR methods (p < 0.001). The results of simulation and in vivo experiments revealed that 3D-mLTS is superior for determining under- or overestimated TSCs while preserving anatomical details. This suggests that the 3D-mLTS method is well suited for the accurate determination of TSC, especially in small focal lesions associated with pathological conditions.

Project description:PurposeTo capture the multiquantum coherence (MQC) 23 Na signal. Different phase-cycling options and sequences are compared in a unified theoretical layout, and a novel sequence is developed.MethodsAn open source simulation overview is provided with graphical explanations to facilitate MQC understanding and access to techniques. Biases such as B0 inhomogeneity and stimulated echo signal were simulated for 4 different phase-cycling options previously described. Considerations for efficiency and accuracy lead to the implementation of a 2D Cartesian single and triple quantum imaging of sodium (CRISTINA) sequence employing two 6-step cycles in combination with a multi-echo readout. CRISTINA was compared to simultaneous single-quantum and triple-quantum-filtered MRI of sodium (SISTINA) under strong static magnetic gradient. CRISTINA capabilities were assessed on 8 × 60 mL, 0% to 5% agarose phantom with 50 to 154 mM 23 Na concentration at 7 T. CRISTINA was demonstrated subsequently in vivo in the brain.ResultsSimulation of B0 inhomogeneity showed severe signal dropout, which can lead to erroneous MQC measurement. Stimulated echo signal was highest at the time of triple-quantum coherences signal maximum. However, stimulated echo signal is separated by Fourier Transform as an offset and did not interfere with MQC signals. The multi-echo readout enabled capturing both single-quantum coherences and triple-quantum coherences signal evolution at once. Signal combination of 2 phase-cycles with a corresponding B0 map was found to recover the signal optimally. Experimental results confirm and complement the simulations.ConclusionConsiderations for efficient MQC measurements, most importantly avoiding B0 signal loss, led to the design of CRISTINA. CRISTINA captures triple-quantum coherences and single-quantum coherences signal evolution to provide complete sodium signal characterization including T2∗ fast, T2∗ slow, MQC amplitudes, and sodium concentration.

Dataset Information

Super-resolution of sodium images from simultaneous ¹ H MRF/²³ Na MRI acquisition.

Publications

Super-resolution of sodium images from simultaneous <sup>1</sup> H MRF/<sup>23</sup> Na MRI acquisition.

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