Comparison and calibration of MP2RAGE quantitative T1 values to multi-TI inversion recovery T1 values

Adam M Saunders; Michael E Kim; Chenyu Gao; Lucas W Remedios; Aravind R Krishnan; Kurt G Schilling; Kristin P O'Grady; Seth A Smith; Bennett A Landman

doi:10.1016/j.mri.2025.110322

Comparison and calibration of MP2RAGE quantitative T1 values to multi-TI inversion recovery T1 values

Magn Reson Imaging. 2025 Jan 3:110322. doi: 10.1016/j.mri.2025.110322. Online ahead of print.

Authors

Adam M Saunders¹, Michael E Kim², Chenyu Gao³, Lucas W Remedios², Aravind R Krishnan³, Kurt G Schilling⁴, Kristin P O'Grady⁵, Seth A Smith⁵, Bennett A Landman⁶

Affiliations

¹ Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, United States. Electronic address: [email protected].
² Department of Computer Science, Vanderbilt University, Nashville, TN, United States.
³ Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, United States.
⁴ Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States.
⁵ Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States.
⁶ Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, United States; Department of Computer Science, Vanderbilt University, Nashville, TN, United States; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States.

PMID: 39756665
DOI: 10.1016/j.mri.2025.110322

Abstract

While typical qualitative T1-weighted magnetic resonance images reflect scanner and protocol differences, quantitative T1 mapping aims to measure T1 independent of these effects. Changes in T1 in the brain reflect structural changes in brain tissue. Magnetization-prepared two rapid acquisition gradient echo (MP2RAGE) is an acquisition protocol that allows for efficient T1 mapping with a much lower scan time per slab compared to multi-TI inversion recovery (IR) protocols. We collect and register B1-corrected MP2RAGE acquisitions with an additional inversion time (MP3RAGE) alongside multi-TI selective inversion recovery acquisitions for four subjects. We use a maximum a posteriori (MAP) T1 estimation method for both MP2RAGE and compare to typical point estimate MP2RAGE T1 mapping, finding no bias from MAP MP2RAGE but a sensitivity to B1 inhomogeneities with MAP MP3RAGE. We demonstrate a tissue-dependent bias between MAP MP2RAGE T1 estimates and the multi-TI inversion recovery T1 values. To correct this bias, we train a patch-based ResNet-18 to calibrate the MAP MP2RAGE T1 estimates to the multi-TI IR T1 values. Across four folds, our network reduces the RMSE significantly (white matter: from 0.30 ± 0.01 s to 0.11 ± 0.02 s, subcortical gray matter: from 0.26 ± 0.02 s to 0.10 ± 0.02 s, cortical gray matter: from 0.36 ± 0.02 s to 0.17 ± 0.03 s). Using limited paired training data from both sequences, we can reduce the error between quantitative imaging methods and calibrate to one of the protocols with a neural network.

Keywords: Calibration; MP2RAGE; Multi-TI inversion recovery; Quantitative imaging; T1 mapping.