Quantitative imaging metrics derived from magnetic resonance fingerprinting using ISMRM/NIST MRI system phantom: An international multicenter repeatability and reproducibility study.

Abstract

To compare the bias and inherent reliability of the quantitative (T1 and T2 ) imaging metrics generated from the magnetic resonance fingerprinting (MRF) technique using the ISMRM/NIST system phantom in an international multicenter setting. ISMRM/NIST MRI system phantom provides standard reference T1 and T2 relaxation values (vendor-provided) for each of the 14 vials in T1 and T2 arrays. MRF-SSFP scans repeated over 30days on GE 1.5 and 3.0T scanners at three collaborative centers. MRF estimated T1, and T2 values averaged over 30days were compared with the phantom vendor-provided and spin-echo (SE) based convention gold standard (GS) method. Repeatability and reproducibility were characterized by the within-case coefficient of variation (wCV) of the MRF data acquired over 30days, along with the biases. For the wide ranges of MRF estimated T1 values, vials #1-8 (T1 relaxation time between 2033 and 184ms) exhibited a wCV less than 3% and 4%, respectively, on 3.0 and 1.5T scanners. T2 values in vials #1-8 (T2 relaxation, 1044-45ms) have shown wCV to be <7% on both 3.0 and 1.5T scanners. A stronger linear correlation overall for T1 (R2 =0.9960 and 0.9963 at center-1 and center-2 on 3.0T scanner, and R2 =0.9951 and 0.9988 at center-1 and center-3 on 1.5T scanner) compared to T2 (R2 =0.9971 and 0.9972 at center-1 and center-2 on 3.0T scanner, and R2 =0.9815 and 0.9754 at center-1 and center-3 on 1.5T scanner). Bland-Altman (BA) analysis showed MRF based T1 and T2 values were within the limit of agreement (LOA) except for one data point. The mean difference or bias and 95% lower bound (LB) and upper bound (UB) LOA are reported in the format; mean bias: 95% LB LOA: 95% UB LOA. The biases for T1 values were 21.34: -50.00: 92.69, 21.32: -47.29: 89.94ms, and for T2 values were -19.88: -42.37: 2.61, -19.06: -43.58: 5.45ms on 3.0T scanner at center-1 and center-2, respectively. Similarly, on 1.5T scanner biases for T1 values were 26.54: -53.41: 106.50, 9.997: -51.94: 71.94ms, and for T2 values were -23.84: -135.40: 87.76, -37.30: 134.30: 59.73ms at center-1 and center-3, respectively. Additionally, the correlation between the SE based GS and MRF estimated T1 and T2 values (R2 =0.9969 and 0.9977) showed a similar trend as we observed between vendor-provided and MRF estimated T1 and T2 values (R2 =0.9963 and 0.9972). In addition to correlation, BA analysis showed that all the vials are within the LOA between the GS and vendor-provided for the T1 values and except one vial for T2 . All the vials are within the LOA between GS and MRF except one vial in T1 and T2 array. The wCV for reproducibility was <3% for both T1 and T2 values in vials #1-8, for all the 14 vials, wCV calculated for reproducibility was <4% for T1 values and <5% for T2 . This study shows that MRF is highly repeatable (wCV <4% for T1 and <7% for T2 ) and reproducible (wCV < 3% for both T1 and T2 ) in certain vials (vials #1-8).