3D-QALAS synthetic MRI with Zero-DeepSub in children: initial experience including post-contrast imaging feasibility

Magnetic resonance imaging (MRI) in children requires multiple sequences, leading to lengthy exams and motion-related challenges. Synthetic MRI generates multiple contrasts from a single acquisition, and integration of 3D-quantification using an interleaved Look-Locker acquisition sequence with a T2 preparation pulse (3D-QALAS) sequence with scan-specific deep-learning-based subspace reconstruction (Zero-DeepSub) enables high-resolution isotropic imaging with potential clinical utility.

To evaluate synthetic images generated from a 3D-QALAS sequence with Zero-DeepSub relative to conventional MRI sequences in pediatric brain MRI.

This prospective initial experience included 26 pediatric patients (mean age 8.4 years) who underwent clinically indicated brain MRI between November 2023 and January 2024. Synthetic T1-weighted, T2-weighted, and fluid-attenuated inversion recovery (FLAIR) images were generated from quantitative maps using 3D-QALAS with Zero-DeepSub reconstruction. Two neuroradiologists independently assessed seven predefined imaging findings on synthetic and conventional images, with discrepancies adjudicated by a third reader. This reader also performed a semiquantitative evaluation of image quality using a 5-point Likert scale. Statistical analysis included descriptive statistics, interobserver agreement (Cohen's kappa), and Wilcoxon signed-rank tests; positive predictive value (PPV) and negative predictive value (NPV) were also calculated.

Synthetic images showed high sensitivity and specificity for mass/lesion, encephalomalacia, and collections, with perfect reader agreement. Gliosis demonstrated high sensitivity but moderate specificity for one reader. Abnormal enhancement had the lowest sensitivity (0.40). Interobserver agreement was moderate for gliosis (κ=0.55) and almost perfect (κ=0.83-1.00) for other findings. Semiquantitative evaluation revealed no significant difference between synthetic and conventional FLAIR, T1-weighted imaging, or post-contrast sequences (P>0.1), while conventional T2-weighted imaging was significantly superior (P<0.001).

3D-QALAS with Zero-DeepSub reconstruction enables the synthesis of high-resolution, clinically interpretable brain images in pediatric patients, including post-contrast sequences. While conventional T2-weighted imaging remained superior, other synthetic contrasts were rated comparable to conventional images. This promising technique holds potential to reduce scan times in pediatric neuroimaging protocols, but further optimization and validation are required before clinical implementation.