Simultaneous proton magnetic resonance fingerprinting and sodium MRI

Self Cite

To develop a 3D MR technique to simultaneously acquire proton multiparametric maps (T 1 , T 2 , and proton density) and sodium density weighted images over the whole brain. Methods:We implemented a 3D stack-of-stars MR pulse sequence which consists of interleaved proton ( 1 H) and sodium ( 23 Na) excitations, tailored slice encoding gradients that can encode the same slice for both nuclei, and simultaneous readout with different radial trajectories ( 1 H, full-radial; 23 Na, center-out radial).The receive chain of our 7T scanner was modified to enable simultaneous acquisition of 1 H and 23 Na signal. A heuristically optimized flip angle train was implemented for proton MR fingerprinting (MRF). The SNR and the accuracy of proton T 1 and T 2 were evaluated in phantoms. Finally, in vivo application of the method was demonstrated in five healthy subjects. Results:The SNR for the simultaneous measurement was almost identical to that for the single-nucleus measurements (<2% change). The proton T 1 and T 2 maps remained similar to the results from a reference 2D MRF technique (normalized RMS error in T 1 ≈ 4.2% and T 2 ≈ 11.3%). Measurements in healthy subjects corroborated these results and demonstrated the feasibility of our method for in vivo application. The in vivo T 1 values measured using our method were lower than the results measured by other conventional techniques.Conclusions: With the 3D simultaneous implementation, we were able to acquire sodium and proton density weighted images in addition to proton T 1 , T 2 , and B + 1 from 1 H MRF that covers the whole brain volume within 21 min.

Section: Resultsmentioning

confidence: 99%

Simultaneous 3D acquisition of¹H MRF and²³Na MRI

Hodono

Dergachyova

et al. 2021

Self Cite

“…1 H‐MRF was established in recent years and found a large variety of applications 40‐42 . A bridge between 1 H‐MRF and X‐nuclei imaging was built by Yu et al, 43 enabling simultaneous 1 H‐MRF and 23 Na imaging. However, to our knowledge, the application of MRF in X‐nuclei MR is currently limited to rapid quantification of the creatine kinase reaction rate 25 and separation of signal originating from different compartments 24 .…”

Section: Discussionmentioning

confidence: 99%

Sodium relaxometry using ²³Na MR fingerprinting: A proof of concept

Kratzer

Flassbeck

Nagel

et al. 2020

Purpose To evaluate the feasibility of 23Na MR fingerprinting (MRF) for simultaneous quantification of T1, T2l∗, T2s∗, T2∗ in addition to ΔB0. Methods A framework for sodium relaxometry using MRF at 7T was developed, allowing simultaneous measurement of relaxation times and inhomogeneities in the static field. The technique distinguishes between bi‐ and monoexponential transverse relaxation and was validated in simulations with respect to the ground truth. In phantom measurements, a resolution of 2 × 2 × 12 mm3 was achieved within 1 h acquisition time, and the resulting parameter maps were compared to results from reference methods. Relaxation times in five healthy volunteers were measured with a resolution of 4 × 4 × 12 mm3. Results Phantom experiments revealed an agreement between the relaxation times obtained via 23Na‐MRF and the reference methods. In white matter, a longitudinal relaxation constant of T1 = 38.9 ± 4.8 ms was found, while values of T2l∗ = 29.2 ± 4.9 ms and T2s∗ = 4.7 ± 1.2 ms were found for the long and short component of the transverse relaxation. In cerebrospinal fluid, T1 was 67.7 ± 6.3 ms and T2∗ = 41.5 ± 3.4 ms. Conclusion This work demonstrates the feasibility of 23Na‐MRF for relaxometry in sodium MRI in both phantom and in vivo studies. Simultaneous quantification of T1, T2l∗, T2s∗, T2∗ and ΔB0 was possible within a 1 h measurement time.

“…22 Non-segmented 1 H acquisition (e.g., TR 1H > 12 ms) is unfavorable because this would reduce the number of 1 H projections by at least a factor of 3, resulting in accordingly lower temporal resolution of the navigator images. To reach a uniform steady state for 1 H, simultaneous acquisition of 23 Na and 1 H would be a possibility, 18,33 which, however, requires additional hardware and therefore limits applicability. Furthermore, due to the golden-angle projection scheme, the temporal resolution of the navigator image data sets can even be adapted retrospectively, depending on the needs of the study.…”

Section: Discussionmentioning

confidence: 99%

Motion‐corrected ²³Na MRI of the human brain using interleaved ¹H 3D navigator images

Wilferth

Müller

Gast

et al. 2022

To evaluate the feasibility of motion correction for sodium ( 23 Na) MRI based on interleaved acquired 3D proton ( 1 H) navigator images.Methods: A 3D radial density-adapted sequence for interleaved 23 Na/ 1 H MRI was implemented on a 7 Tesla whole-body MRI system. The 1 H data obtained during the 23 Na acquisition were used to reconstruct 140 navigator image volumes with a nominal spatial resolution of (2.5 mm) 3 and a temporal resolution of 6 s. The motion information received from co-registration was then used to correct the 23 Na image dataset, which also had a nominal spatial resolution of (2.5 mm) 3 . The approach was evaluated on six healthy volunteers, whose motion during the scans had different intensities and characteristics.Results: Interleaved acquisition of two nuclei did not show any relevant influence on image quality (SNR of 13.0 for interleaved versus 13.2 for standard 23 Na MRI and 176.4 for interleaved versus 178.0 for standard 1 H MRI). The applied motion correction increased the consistency between two consecutive scans for all examined volunteers and improved the image quality for all kinds of motion. The SD of the differences ranged between 2.30% and 6.96% for the uncorrected and between 2.13% and 2.67% for the corrected images. Conclusion:The feasibility of interleaved acquired 1 H navigator images to be used for retrospective motion correction of 23 Na images was successfully demonstrated. The approach neither affected the 23 Na image quality nor elongated the scan time and can therefore be an important tool to improve the accuracy of quantitative 23 Na MRI.