Abstract WP292: Quantitative Susceptibility Mapping for Reliably Measuring Hematoma Volume in Magnetic Resonance Imaging

Abstract

Introduction T2* weighted gradient echo MRI has been increasingly recognized as a sensitive tool in detecting intracerebral hemorrhage. However, its blooming artifacts is highly dependent on imaging parameters including TE, field strength and voxel size, making it difficult to reliably estimate the hematoma volume, a key predictor of morbidity and mortality of hemorrhage. Recently, a novel quantitative susceptibility mapping (QSM) technology has been developed for processing gradient echo MRI data to map tissue susceptibility property without blooming artifacts and dependence on imaging parameters. Hypothesis We assessed the hypothesis that hematoma volume measurement on QSM is independent of imaging parameters, eliminating its TE dependence on gradient echo MRI. Method A retrospective image analysis of MRI was approved by our IRB with HIPPA compliance. We randomly selected 16 patients who underwent intracerebral hemorrhage MRI including a 3D multiecho T2*w sequence: 8-11 echoes with first echo TE/ echo spacing/ TR= 5/5/50 msec. Postprocessed images of gradient echo MRI included susceptibility weighted imaging (SWI), R2* (quantitative 1/T2* mapping), and QSM at various TEs. Hematoma volumes were measured from all these images. Results Linear regression of hematoma volume vs TE over all subjects showed substantial slopes for gradient echo magnitude (0.45±0.31 L/s), SWI (0.52±0.46) and R2* (0.39±0.30) but nearly zero slope for QSM (0.01±0.05). At TE=20 msec, hematoma volume on QSM was 0.80x that on gradient echo magnitude image (R2=0.99), and hematoma volume on CT is also 0.8x that on gradient echo magnitude image according to literature (Stroke 2008;39:2017-2020). Conclusion In conclusion, quantitative susceptibility mapping can provide reliable measurement of hematoma volume, independent echo time and similar to CT.