Localized Quadratic RF Encoded Spin‐Echo With Spiral‐ PRIME Reconstruction: A Practical Alternative to 3D FSE for High‐Resolution Volumetric Brain MRI

ABSTRACT Purpose To extend localized quadratic (LQ) RF encoded spin‐echo imaging with acquisition and reconstruction strategies that improve efficiency and artifact robustness, positioning it as a practical alternative to 3D FSE for high‐resolution volumetric brain MRI. Methods The framework integrates (1) additional gradient‐echo readouts for simultaneous T2*w or PDw with T2w without prolonging scan time, (2) an in‐plane sampling scheme that distributes arms across shot/trajectory types to maximize k‐space coverage and render phase inconsistencies as incoherent residue, (3) sliding‐slice encoding to disperse through‐plane artifacts, (4) a novel loop‐ordering to avoid repeated startup cycles and improve motion robustness, and (5) a hybrid 2D/3D Physics‐based Reconstruction with Iterative Model‐based Enhancement (spiral‐PRIME) performing deblurring, fat–water separation, and 3D wavelet denoising. Healthy‐volunteer imaging (3 T) was compared with fully sampled LQ and conventional 3D FSE using peak signal‐to‐noise ratio, structural similarity index measure, pseudo‐replica SNR gain, and qualitative review. Results Sliding‐slice with loop‐ordering reduced through‐plane artifacts and improved temporal efficiency, while in‐plane sampling dispersed trajectory inconsistencies as incoherent noise. Spiral‐PRIME suppressed undersampling artifacts and noise while preserving fine structure. Relative to spiral‐SENSE, spiral‐PRIME achieved consistent T2w SNR gains of ∼30%–40% in WM/GM and substantially higher gains for T2*w, with CNR improvements most pronounced for GM–WM. Despite R ≈ 2.33 undersampling, reconstructions closely matched fully sampled references and delivered quality comparable to or exceeding 3D FSE. Conclusion LQ spin‐echo with spiral‐PRIME enables efficient, multi‐contrast volumetric brain imaging with robust artifact suppression and clinically meaningful SNR/CNR gains, supporting its potential as a practical alternative to 3D FSE.