Improving spreading projection algorithm for rapid k-space sampling trajectories through minimized off-resonance effects and gridding of low frequencies.
Magn Reson Med
; 90(3): 1069-1085, 2023 09.
Article
em En
| MEDLINE
| ID: mdl-37213029
ABSTRACT
PURPOSE:
Non-Cartesian MRI with long arbitrary readout directions are susceptible to off-resonance artifacts due to patient induced B 0 $$ {B}_0 $$ inhomogeneities. This results in degraded image quality with strong signal losses and blurring. Current solutions to address this issue involve correcting the off-resonance artifacts during image reconstruction or reducing inhomogeneities through improved shimming. THEORY The recently developed SPARKLING algorithm is extended to drastically diminish off-resonance artifacts by generating temporally smooth k-space sampling patterns. For doing so, the cost function which is optimized in SPARKLING is modified using a temporal weighting factor. Additionally, oversampling of the center of k-space beyond the Nyquist criteria is prevented through the use of gridded sampling in the region, enforced with affine constraints.METHODS:
Prospective k-space data was acquired at 3 T on new trajectories, and we show robustness to B 0 $$ {\mathrm{B}}_0 $$ inhomogeneities through in silico experiments by adding Δ B 0 $$ \Delta {\mathrm{B}}_0 $$ through artificial degradation of system B 0 $$ {\mathrm{B}}_0 $$ shimming. Later on, in vivo experiments were carried out to optimize parameters of the new improvements and benchmark the gain in performance.RESULTS:
The improved trajectories allowed for the recovery of signal dropouts observed on original SPARKLING acquisitions at larger B 0 $$ {\mathrm{B}}_0 $$ field inhomogeneities. Furthermore, imposing gridded sampling at the center of k-space provided improved reconstructed image quality with limited artifacts.CONCLUSION:
These advancements allowed us for nearly 4 . 62 × $$ 4.62\times $$ shorter scan time compared to GRAPPA-p4x1, allowing us to reach 600 µm isotropic resolution in 3D T 2 ∗ $$ {\mathrm{T}}_2^{\ast } $$ -w imaging in just 3.3 min at 3 T with negligible degradation in image quality.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Processamento de Imagem Assistida por Computador
/
Imageamento por Ressonância Magnética
Tipo de estudo:
Observational_studies
/
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Magn Reson Med
Assunto da revista:
DIAGNOSTICO POR IMAGEM
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
França