BackgroundQuantitative susceptibility mapping (QSM) offers a consistent hemorrhage volume measurement independent of imaging parameters.PurposeTo investigate the magnetic susceptibility of intracerebral hemorrhage (ICH) as a quantitative measurement for monitoring treatment in hematoma patients.Study TypeProspective.PopulationTwenty‐six patients with acute ICH were recruited and enrolled in treatment including surgery or medication (mannitol) for 1 week.Field Strength/SequenceA 3D gradient echo sequence at 3.0T.AssessmentThe hematoma volumes on computed tomography (CT) and QSM were calculated and used for correlation analysis. Magnetic susceptibility changes from pre‐ to posttreatment were calculated and compared to the National Institutes of Health stroke scale (NIHSS) measure of neurological deficit for each patient.Statistical TestsMean susceptibility values were calculated over each region of interest (ROI). A one‐sample t‐test was used to assess the changes of total volumes and mean magnetic susceptibility of ICH identified between pre‐ and posttreatment images (P < 0.05 was considered significant) and the Bland–Altman analysis with 95% limits of agreement (average difference, ±1.96 SD of the difference). Regression of volume measurements on QSM vs. CT and fitted linear regression of mean susceptibility vs. CT signal intensity for hematoma regions were conducted in all patients.ResultsGood correlation was found between hemorrhage volumes calculated from CT and QSM (CT volume = 0.94*QSM volume, r = 0.98). Comparison of QSM pre‐ and posttreatment showed that the mean ICH volume was reduced by a statistically insignificant amount from 5.74 cm3 to 5.45 cm3 (P = 0.21), while mean magnetic susceptibility was reduced significantly from 0.48 ppm to 0.38 ppm (P = 0.004). A significant positive association was found between changes in magnetic susceptibility values and NIHSS following hematoma treatment (P < 0.01).Data ConclusionsQSM in hematoma assessment, as compared with CT, offers a comparably accurate volume measurement; however, susceptibility measurements may enable improved monitoring of ICH treatment compared to volume measurements alone.Level of Evidence: 2Technical Efficacy: Stage 2J. Magn. Reson. Imaging 2018;48:907–915.