Quantitative imaging metrics derived from magnetic resonance fingerprinting using ISMRM/NIST MRI system phantom: An international multicenter repeatability and reproducibility study
Authors: Shridhar Konar Amaresha , Qian Enlin , Geethanath Sairam , Buonincontri Guido , Obuchowski Nancy A. , Fung Maggie , Gomez Pedro , Schulte Rolf , Cencini Matteo , Tosetti Michela , Schwartz Lawrence H , Shukla‐Dave Amita 
Published: March 2021

PurposeTo 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.MethodISMRM/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 30 days on GE 1.5 and 3.0 T scanners at three collaborative centers. MRF estimated T1, and T2 values averaged over 30 days 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 30 days, along with the biases.ResultFor the wide ranges of MRF estimated T1 values, vials #1‐8 (T1 relaxation time between 2033 and 184 ms) exhibited a wCV less than 3% and 4%, respectively, on 3.0 and 1.5 T scanners. T2 values in vials #1‐8 (T2 relaxation, 1044‐45 ms) have shown wCV to be <7% on both 3.0 and 1.5 T scanners. A stronger linear correlation overall for T1 (R2 = 0.9960 and 0.9963 at center‐1 and center‐2 on 3.0 T scanner, and R2 = 0.9951 and 0.9988 at center‐1 and center‐3 on 1.5 T scanner) compared to T2 (R2 = 0.9971 and 0.9972 at center‐1 and center‐2 on 3.0 T scanner, and R2 = 0.9815 and 0.9754 at center‐1 and center‐3 on 1.5 T 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: 89.94 ms, and for T2 values were −19.88: −42.37: 2.61, −19.06: −43.58: 5.45 ms on 3.0 T scanner at center‐1 and center‐2, respectively. Similarly, on 1.5 T scanner biases for T1 values were 26.54: −53.41: 106.50, 9.997: −51.94: 71.94 ms, and for T2 values were −23.84: −135.40: 87.76, −37.30: 134.30: 59.73 ms 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.ConclusionThis 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).