Turley, Dallas

BackgroundQuantitative susceptibility mapping (QSM) and dynamic contrast‐enhanced quantitative permeability (DCEQP) on magnetic resonance (MR) have been shown to correlate with neurovascular disease progression as markers of vascular leakage and hemosiderin deposition. Applying these techniques as monitoring biomarkers in clinical trials will be necessary; however, their validation across multiple MR platforms and institutions has not been rigorously verified.PurposeTo validate quantitative measurement of MR biomarkers on multiple instruments at different institutions.Study TypePhantom validation between platforms and institutions.Phantom ModelT1/susceptibility phantom, two‐compartment dynamic flow phantom.Field Strength/Sequence3T/QSM, T1 mapping, dynamic 2D SPGR.AssessmentPhilips Ingenia, Siemens Prisma, and Siemens Skyra at three different institutions were assessed. A QSM phantom with concentrations of gadolinium, corresponding to magnetic susceptibilities of 0, 0.1, 0.2, 0.4, and 0.8 ppm was assayed. DCEQP was assessed by measuring a MultiHance bolus as the consistency of the width ratio of the curves at the input and outputs over a range of flow ratios between outputs.Statistical TestsEach biomarker was assessed by measures of accuracy (Pearson correlation), precision (paired t‐test between repeated measurements), and reproducibility (analysis of covariance [ANCOVA] between instruments).ResultsQSM accuracy of r2 > 0.997 on all three platforms was measured. Precision (P = 0.66 Achieva, P = 0.76 Prisma, P = 0.69 Skyra) and reproducibility (P = 0.89) were good. T1 mapping of accuracy was r2 > 0.98. No significant difference between width ratio regression slopes at site 2 (P = 0.669) or site 3 (P = 0.305), and no significant difference between width ratio regression slopes between sites was detected by ANCOVA (P = 0.48).Data ConclusionThe phantom performed as expected and determined that MR measures of QSM and DCEQP are accurate and consistent across repeated measurements and between platforms.Level of Evidence: 1Technical Efficacy Stage: 2J. Magn. Reson. Imaging 2020;51:1192–1199.

Background: Cerebral cavernous malformation is a genetic neurovascular disorder causing aberrant angiogenesis and lesion development within capillary beds. Lesions exhibit impaired endothelial barrier function, causing blood-brain barrier leakage and hemorrhage. Quantitative MRI biomarkers (dynamic contrast-enhanced quantitative permeability (DCEQP) and quantitative susceptibility mapping (QSM)) have been shown to correlate with CCM disease progression as measures of barrier leakage and hemorrhagic iron deposition, and there is interest in utilizing these biomarkers as endpoints in clinical trials. However, their consistencies across multiple platforms and institutions has not yet been rigorously verified. Materials and Methods: Instruments used were a 3T Philips Ingenia at University of Chicago and a 3T Siemens Prisma at Northwestern University. QSM was assessed by five balloons filled with varying concentrations of MultiHance, corresponding to magnetic susceptibilities of 0, 0.1, 0.2, 0.4, and 0.8, surrounded by an agarose gel. Permeability was assessed by the injection of a bolus of MultiHance through a coiled hose inside a water-filled shell, and the consistency of the peak-to-peak ratio of the curves at the input and output was measured. Each biomarker was assessed by accuracy (to expected values, Pearson correlation), precision (between repeated measurements, paired t-test), and reproducibility (between instruments, paired t-test). Results: QSM measured with an accuracy of r 2 = 0.997 on the Philips Achieva and r 2 = 0.999 on the Siemens Prisma. Each scanner had adequate precision between measurements, showing no significant difference by a paired t-test (p = 0.66 Achieva, p = 0.45 Prisma), and the reproducibility between scanners also showed no significant difference (p = 0.89). The peak-to-peak ratio on DCEQP scans was accurate (r 2 = 0.998), precise between measurements (p = 0.54), and repeatable between instruments (p = 0.49). Conclusion: Quantitative imaging biomarkers DCEQP and QSM are accurate, consistent across multiple measurements, and between platforms and will be useful for future clinical trials in CCM.