Optimising the diagnostic accuracy of First post-contrAst SubtracTed breast MRI (FAST MRI) through interpretation-training: a multicentre e-learning study, mapping the learning curve of NHS Breast Screening Programme (NHSBSP) mammogram readers using an enriched dataset

Abstract

Background: Abbreviated breast MRI (FAST MRI) is being introduced into clinical practice. Specificity optimisation is essential to minimise harm through false positive results for populations with low pre-test probability. This study aimed to optimise diagnostic accuracy through the adaptation of a FAST MRI interpretation-training programme. Methods: A FAST MRI interpretation-training programme was adapted to provide additional training during the assessment task (interpretation of an enriched dataset of 125 FAST MRI scans) by giving readers feedback about the true outcome of each scan immediately after each scan was interpreted (formative assessment). The training programme was additionally adapted for remote e-learning delivery. Study design: prospective, blinded interpretation of an enriched dataset by multiple readers. Results: 43 mammogram readers completed the training, 22 who interpreted breast MRI in their clinical role (Group 1) and 21 who did not (Group 2). Overall sensitivity was 83% (95%CI 81-84%; 1994/2408), specificity 94% (95%CI 93–94%; 7806/8338), readers’ agreement with the true outcome kappa = 0.75 (95%CI 0.74-0.77) and diagnostic odds ratio = 70.67 (95%CI 61.59-81.09). Group 1 readers showed similar sensitivity (84%) to Group 2 (82% p=0.14), but slightly higher specificity (94% v. 93%, p=0.001). Concordance with the ground truth increased significantly with the number of FAST MRI scans read through the formative assessment task (p=0.002) but by differing amounts depending on whether or not a reader had previously attended FAST MRI training (interaction p=0.02). Concordance with the ground truth was significantly associated with reading batch size (p=0.02), tending to worsen when more than 50 scans were read per batch. Group 1 took a median of 56 seconds (range 8-47466) to interpret each FAST MRI scan compared with 78 seconds (14-22830, p <0.0001) for Group 2. Conclusions: Provision of immediate feedback to mammogram readers during the assessment test set reading task increased specificity for FAST MRI interpretation and achieved high diagnostic accuracy. Optimal reading-batch size for FAST MRI was 50 reads per batch. Trial registration (25/09/2019): ISRCTN16624917