Abstract 114: Changes In Quantitative Susceptibility Mapping On Magnetic Resonance Imaging During Prospective Follow-Up Of Cavernous Angiomas With Symptomatic Hemorrhage In Trial Readiness Project

Background: Quantitative susceptibility mapping (QSM) is a measure of iron content, and ≥6% increase in QSM has been correlated with new hemorrhage in previously stable cavernous angiomas. Longitudinal changes in QSM are not known in cavernous angiomas with symptomatic hemorrhage (CASH) with high rates of rebleeding and are the targets of novel pharmacotherapies. In a prospective multisite Trial Readiness project (clinicaltrials.gov NCT03652181), QSM is longitudinally assessed. Methods: Trial eligible subjects with CASH in the prior year and not undergoing lesion resection or radiation, were enrolled. Mean QSM of CASH lesion was acquired at baseline and at 1 and 2 year planned follow-ups. Relative change in mean lesional QSM during each follow-up year was assessed, and any symptomatic hemorrhage (SH), asymptomatic changes (AC; defined as subclinical bleed or growth) in the lesion during the same epoch. Results: Paired QSM assessments were completed to date in 99 CASH lesions (67 year 1, and 32 year 2) and are reported herein. Four SH and 6 ACs occurred during 1 st follow-up year, and 3 SH during 2 nd year. QSM increased in 54 lesion-years, decreased in 44, and remained stable in 1. The % lesional QSM change in year 1 was significantly higher than that observed in year 2 (mean +9.33, SD 37.52 vs. +5.20; SD= 24.86; p=0.05; Spearman correlation ρ -0.36). CAs with clinical SH or AC had a significantly higher % QSM change than lesions without (mean +28.03, SD 17.77 vs. +4.97, SD= 34.75; p=0.0014). All 13 lesions with SH/AC demonstrated a QSM increase ≥6% while 31 of 86 (36%) lesions with no clinical events had a ≥6% QSM increase. Conclusion: QSM change of ≥6% is present in every CASH lesion manifesting a new SH or AC (100% specificity), and is more common than clinical events (3.4X higher sensitivity). The biomarker can hence be used as a more sensitive categorical outcome than SH or AC in clinical trials of novel therapies aimed at bleeding in CASH lesions. Effect of an intervention on % QSM change may also be proposed as a time-averaged difference between 2 arms using a repeated measures analysis implemented as an unadjusted linear mixed model. These results are the basis of application for certification by the U.S F.D.A. of QSM as a monitoring biomarker of drug effect in CASH.