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Multicenter reproducibility of quantitative susceptibility mapping in a gadolinium phantom using MEDI+0 automatic zero referencing.

ABSTRACT: PURPOSE:To determine the reproducibility of quantitative susceptibility mapping at multiple sites on clinical and preclinical scanners (1.5 T, 3 T, 7 T, and 9.4 T) from different vendors (Siemens, GE, Philips, and Bruker) for standardization of multicenter studies. METHODS:Seven phantoms distributed from the core site, each containing 5 compartments with gadolinium solutions with fixed concentrations between 0.625 mM and 10 mM. Multi-echo gradient echo scans were performed at 1.5 T, 3 T, 7 T, and 9.4 T on 12 clinical and 3 preclinical scanners. DICOM images from the scans were processed into quantitative susceptibility maps using the Laplacian boundary value (LBV) and MEDI+0 automatic uniform reference algorithm. Region of interest (ROI) analyses were performed by a physicist to determine agreement between results from all sites. Measurement reproducibility was assessed using regression, Bland-Altman plots, and the intra-class correlation coefficient (ICC). RESULTS:Quantitative susceptibility mapping (QSM) from all scanners had similar, artifact-free visual appearance. Regression analysis showed a linear relationship between gadolinium concentrations and average QSM measurements for all phantoms (y = 350x - 0.0346, r2 >0.99). The SD of measurements increased almost linearly from 32 ppb to 230 ppb as the measured susceptibility increased from 0.26 ppm to 3.56 ppm. A Bland-Altman plot showed the bias, upper, and lower limits of agreement for all comparisons were -10, -210, and 200 ppb, respectively. The ICC was 0.991 with a 95% CI (0.973, 0.99). CONCLUSIONS:QSM shows excellent multicenter reproducibility for a large range of susceptibility values encountered in cranial and extra-cranial applications on a diverse set of scanner platforms.

SUBMITTER: Deh K

PROVIDER: S-EPMC6289704 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Multicenter reproducibility of quantitative susceptibility mapping in a gadolinium phantom using MEDI+0 automatic zero referencing.

Deh Kofi K Kawaji Keigo K Bulk Marjolein M Van Der Weerd Louise L Lind Emelie E Spincemaille Pascal P McCabe Gillen Kelly K Van Auderkerke Johan J Wang Yi Y Nguyen Thanh D TD

Magnetic resonance in medicine 20181004 2

<h4>Purpose</h4>To determine the reproducibility of quantitative susceptibility mapping at multiple sites on clinical and preclinical scanners (1.5 T, 3 T, 7 T, and 9.4 T) from different vendors (Siemens, GE, Philips, and Bruker) for standardization of multicenter studies.<h4>Methods</h4>Seven phantoms distributed from the core site, each containing 5 compartments with gadolinium solutions with fixed concentrations between 0.625 mM and 10 mM. Multi-echo gradient echo scans were performed at 1.5 ...[more]

PMID: 30284727

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Project description:PURPOSE:To determine the in vitro accuracy, test-retest repeatability, and interplatform reproducibility of T1 quantification protocols used for dynamic contrast-enhanced MRI at 1.5 and 3?T. METHODS:A T1 phantom with 14 samples was imaged at eight centers with a common inversion-recovery spin-echo (IR-SE) protocol and a variable flip angle (VFA) protocol using seven flip angles, as well as site-specific protocols (VFA with different flip angles, variable repetition time, proton density, and Look-Locker inversion recovery). Factors influencing the accuracy (deviation from reference NMR T1 measurements) and repeatability were assessed using general linear mixed models. Interplatform reproducibility was assessed using coefficients of variation. RESULTS:For the common IR-SE protocol, accuracy (median error across platforms?=?1.4-5.5%) was influenced predominantly by T1 sample (P?<?10-6 ), whereas test-retest repeatability (median error?=?0.2-8.3%) was influenced by the scanner (P?<?10-6 ). For the common VFA protocol, accuracy (median error?=?5.7-32.2%) was influenced by field strength (P?=?0.006), whereas repeatability (median error?=?0.7-25.8%) was influenced by the scanner (P?<?0.0001). Interplatform reproducibility with the common VFA was lower at 3?T than 1.5?T (P?=?0.004), and lower than that of the common IR-SE protocol (coefficient of variation 1.5T: VFA/IR-SE?=?11.13%/8.21%, P?=?0.028; 3?T: VFA/IR-SE?=?22.87%/5.46%, P?=?0.001). Among the site-specific protocols, Look-Locker inversion recovery and VFA (2-3 flip angles) protocols showed the best accuracy and repeatability (errors?<?15%). CONCLUSIONS:The VFA protocols with 2 to 3 flip angles optimized for different applications achieved acceptable balance of extensive spatial coverage, accuracy, and repeatability in T1 quantification (errors?<?15%). Further optimization in terms of flip-angle choice for each tissue application, and the use of B1 correction, are needed to improve the robustness of VFA protocols for T1 mapping. Magn Reson Med 79:2564-2575, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Project description: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).

Project description:PurposeThe purpose of this paper was to design, manufacture, and evaluate a tissue equivalent, dual magnetic resonance/computed tomography (MR/CT) visible anthropomorphic head and neck (H&N) phantom. This phantom was specially designed as an end-to-end quality assurance (QA) tool for MR imaging guided radiotherapy (MRIgRT) systems participating in NCI-sponsored clinical trials.MethodThe MRIgRT H&N phantom was constructed using a water-fillable acrylic shell and a custom insert that mimics an organ at risk (OAR) and target structures. The insert consists of a primary and secondary planning target volume (PTV) manufactured of a synthetic Clear Ballistic gel, an acrylic OAR and surrounding tissue fabricated using melted Superflab. Radiochromic EBT3 film and thermoluminescent detectors (TLDs) were used to measure the dose distribution and absolute dose, respectively. The phantom was evaluated by conducting an end-to-end test that included: imaging on a GE Lightspeed CT simulator, planning on Monaco treatment planning software (TPS), verifying treatment setup with MR, and irradiating on Elekta's 1.5 T Unity MR linac system. The phantom was irradiated three times using the same plan to determine reproducibility. Three institutions, equipped with either ViewRay MRIdian 60 Co or ViewRay MRIdian Linac, were used to conduct a feasibility study by performing independent end-to-end studies. Thermoluminescent detectors were evaluated in both reproducibility and feasibility studies by comparing ratios of measured TLD to reported TPS calculated values. Radiochromic film was used to compare measured planar dose distributions to expected TPS distributions. Film was evaluated by using an in-house gamma analysis software to measure the discrepancies between film and TPS.ResultsThe MRIgRT H&N phantom on the Unity system resulted in reproducible TLD doses (SD < 1.5%). The measured TLD to calculated dose ratios for the Unity system ranged from 0.94 to 0.98. The Viewray dose result comparisons had a larger range (0.95-1.03) but these depended on the TPS dose calculations from each site. Using a 7%/4 mm gamma analysis, Viewray institutions had average axial and sagittal passing rates of 97.3% and 96.2% and the Unity system had average passing rates of 97.8% and 89.7%, respectively. All of the results were within the Imaging and Radiation Oncology Core in Houston (IROC-Houston) standard credentialing criteria of 7% on TLDs, and >85% of pixels passing gamma analysis using 7%/4 mm on films.ConclusionsAn MRIgRT H&N phantom that is tissue equivalent and visible on both CT and MR was developed. The results from initial reproducibility and feasibility testing of the MRIgRT H&N phantom using the tested MGIgRT systems suggests the phantom's potential utility as a credentialing tool for NCI-clinical trials.

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Dataset Information

Multicenter reproducibility of quantitative susceptibility mapping in a gadolinium phantom using MEDI+0 automatic zero referencing.

Publications

Multicenter reproducibility of quantitative susceptibility mapping in a gadolinium phantom using MEDI+0 automatic zero referencing.

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