Quantitative MR relaxometry, particularly Transient-State Relaxometry (TSR) methods such as MR Fingerprinting (MRF) on Siemens, Quantitative Transient-state Imaging (QTI) on GE, and MR Spin Tomography in Time-Domain (MR-STAT) on Philips, offer promising tools for brain pathology diagnosis and assessment. These methods are known for short acquisition times and motion tolerance. However, the lack of standardized TSR method across vendors may hinder multi-center studies. This study aims to evaluate repeatability and reproducibility of TSR T1 and T2 maps acquired at 3T across three MR vendors.
Vendor-specific TSR protocols were acquired at four sites using scanners from GE, Siemens, and Philips. A phantom was scanned at all sites, acquiring two repeated TSR scans and a gold standard (GS) protocol. For in-vivo testing, five healthy volunteers underwent two TSR scans at each site. TSR accuracy and repeatability were assessed using Bland-Altman analysis and Coefficient-of-Variation (CV), and a General Linear Model (GLM) was used to evaluate bias.
TSR measurements in phantoms showed excellent agreement with GS values, and excellent intra-site repeatability (bias<4%) and inter-site reproducibility (bias<11%). In vivo, T1 and T2 values in solid tissues exhibited low intra-site variability (CV=2-4%) and slightly higher inter-site CV=3-20%. GLM analysis revealed uniform 100ms-bias for T1 attributable to MT effect and spatially inhomogeneous 10ms-bias for T2 across sites potentially due to residual B1 inhomogeneities.
TSR methods demonstrated excellent repeatability and good cross-vendor reproducibility, making them suitable for multi-center studies. However, vendor-agnostic sequences are needed to improve reproducibility and detect small pathological variations.
Acknowledgement
This study was partially supported by the Italian Ministry of Health under the grant “RC 2024” to IRCCS Fondazione Stella Maris and the grant FIABA PNRR-MR1-2022-12375648 funded by the European Union – Next Generation EU – NRRP M6C2 – Investment 2.1 Enhancement and strengthening of biomedical research in the NHS.
