Efficient standardization of clinical T2‐weighted images: Phase‐conjugacy e‐CAMP with projected gradient descent

• Published in: Magnetic resonance in medicine 2024-12, Vol.92 (6), p.2723-2733
• Main Authors: Zhang, Horace Z, Elsaid, Nahla M H, Sun, Heng, Tagare, Hemant D, Galiana, Gigi
• Format: Article
• Language: English
• Subjects: Algorithms; Heterogeneity; Parameters; Standardization; Substantia alba
• ISSN: 0740-3194; 1522-2594; 1522-2594
• DOI: 10.1002/mrm.30214

PurposeTo standardize T 2$$ {}_2 $$‐weighted images from clinical Turbo Spin Echo (TSE) scans by generating corresponding T 2$$ {}_2 $$ maps with the goal of removing scanner‐ and/or protocol‐specific heterogeneity.MethodsThe T 2$$ {}_2 $$ 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).ResultsThe algorithm achieves accuracy comparable to methods with customized sampling schemes for accelerated T 2$$ {}_2 $$ mapping. The results are insensitive to the tunable parameters, and the relaxed background phase prior produces better T 2$$ {}_2 $$ maps compared to the strict real‐value enforcement. It is worth noting that the algorithm works well with challenging T 2$$ {}_2 $$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.ConclusionThe novel methodological development creates an efficient algorithm that allows for T 2$$ {}_2 $$ map generated from TSE data with typical clinical parameters, such as high resolution, long echo train length, and low echo spacing. Reconstruction of T 2$$ {}_2 $$ maps from TSE data with typical clinical parameters has not been previously reported.