Virtual MOLLI Target: Generative Adversarial Networks Toward Improved Motion Correction in MRI Myocardial T1 Mapping

Background The modified Look‐Locker inversion recovery (MOLLI) sequence is commonly used for myocardial T1 mapping. However, it acquires images with different inversion times, which causes difficulty in motion correction for respiratory‐induced misregistration to a given target image. Hypothesis Using a generative adversarial network (GAN) to produce virtual MOLLI images with consistent heart positions can reduce respiratory‐induced misregistration of MOLLI datasets. Study Type Retrospective. Population 1071 MOLLI datasets from 392 human participants. Field Strength/Sequence Modified Look‐Locker inversion recovery sequence at 3 T. Assessment A GAN model with a single inversion time image as input was trained to generate virtual MOLLI target (VMT) images at different inversion times which were subsequently used in an image registration algorithm. Four VMT models were investigated and the best performing model compared with the standard vendor‐provided motion correction (MOCO) technique. Statistical Tests The effectiveness of the motion correction technique was assessed using the fitting quality index (FQI), mutual information (MI), and Dice coefficients of motion‐corrected images, plus subjective quality evaluation of T1 maps by three independent readers using Likert score. Wilcoxon signed‐rank test with Bonferroni correction for multiple comparison. Significance levels were defined as P < 0.01 for highly significant differences and P < 0.05 for significant differences. Results The best performing VMT model with iterative registration demonstrated significantly better performance (FQI 0.88 ± 0.03, MI 1.78 ± 0.20, Dice 0.84 ± 0.23, quality score 2.26 ± 0.95) compared to other approaches, including the vendor‐provided MOCO method (FQI 0.86 ± 0.04, MI 1.69 ± 0.25, Dice 0.80 ± 0.27, quality score 2.16 ± 1.01). Data Conclusion Our GAN model generating VMT images improved motion correction, which may assist reliable T1 mapping in the presence of respiratory motion. Its robust performance, even with considerable respiratory‐induced heart displacements, may be beneficial for patients with difficulties in breath‐holding. Level of Evidence 3 Technical Efficacy Stage 1