Efficient standardization of clinical T 2 ‐weighted images: Phase‐conjugacy e‐CAMP with projected gradient descent

• Published in: Magnetic resonance in medicine Vol. 92; no. 6; p. 2723
• Main Authors: Zhang, Horace Z., Elsaid, Nahla M. H., Sun, Heng, Tagare, Hemant D., Galiana, Gigi
• Format: Journal Article
• Language: English
• Published: United States 01.12.2024
• Subjects: Algorithms; Brain - diagnostic imaging; Humans; Image Interpretation, Computer-Assisted - methods; Image Processing, Computer-Assisted - methods; Magnetic Resonance Imaging - methods; Phantoms, Imaging; Reproducibility of Results; projected gradient descent; turbo spin echo; T; phase conjugacy; map; e‐CAMP
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.30214

To standardize T -weighted images from clinical Turbo Spin Echo (TSE) scans by generating corresponding T maps with the goal of removing scanner- and/or protocol-specific heterogeneity. The T map is estimated by minimizing an objective function containing a data fidelity term in a Virtual Conjugate Coils (VCC) framework, where the signal evolution model is expressed as a linear constraint. The objective function is minimized by Projected Gradient Descent (PGD). The algorithm achieves accuracy comparable to methods with customized sampling schemes for accelerated T mapping. The results are insensitive to the tunable parameters, and the relaxed background phase prior produces better T maps compared to the strict real-value enforcement. It is worth noting that the algorithm works well with challenging T w-TSE data using typical clinical parameters. The observed normalized root mean square error ranges from 6.8% to 12.3% over grey and white matter, a clinically common level of quantitative map error. The novel methodological development creates an efficient algorithm that allows for T map generated from TSE data with typical clinical parameters, such as high resolution, long echo train length, and low echo spacing. Reconstruction of T maps from TSE data with typical clinical parameters has not been previously reported.