To compare the performance of coronal contrast-enhanced T1-weighted (ceT1-w) and T2-weighted (T2-w) sequences for diagnosing progression during the MRI follow-up of Non-Functioning Pituitary MacroAdenomas (NFPMAs).

106 patients, who had at least two MRIs for the follow-up of NFPMA, were enrolled retrospectively. The largest adenoma diameter was measured on coronal ceT1-w sequences and separately on T2-w sequences for all follow-up MRIs. Interobserver variability was also assessed by 2 independent neuroradiologists in a sample series of 100 examinations. Progression was defined by an increase ≥ 2 mm in diameter between 2 MRIs. Progression thresholds of 3 and 4 mm were also tested. The results of ceT1-w and T2-w sequences were analysed for concordance.

93.1% concordance was achieved between ceT1-w and T2-w coronal sequences in 580 follow-up MRIs. In the case of progression detected on at least one sequence, 64.4% concordance was documented for a 2-mm threshold, 87.7% for 3-mm and 97.1% for 4-mm. Discordance was mainly observed on the first postoperative MRI and in case of NFPMAs with multiple recurrences. Kappa was better for diagnosing progression on T2-w than on ceT1-w sequences (0.67 vs. 0.54). It should be noted that 100% agreement was observed between the 2 sequences in the 82 follow-up MRIs of patients with complete surgical resection.

93.1% concordance was achieved for coronal ceT1-w and T2-w sequences during the MRI follow-up of NFPMAs, thus challenging systematic injection of gadolinium. If MRI without gadolinium injection is a first-line option, our results suggest that ceT1-w sequences should be reserved for the first postoperative MRI and for the follow-up of aggressive and recurrent NFPMAs.