Abstract TP118: Brain Iron Quantification By MRI In Normal Human Subjects And Contra-lesional Hemisphere Of Intraparenchymal Hemorrhage (IPH) Patients

Abstract

Introduction: Human cadaveric studies have correlated higher transverse relaxation rate (R2*) to higher tissue Fe concentrations. These methods enable non-invasive brain tissue Fe quantification after IPH. This study tested these methods on live human IPH patients vs. normal subjects to assess using the contra-lesional cerebral hemisphere as an internal control for future longitudinal tissue Fe quantification studies. Methods: Normal and IPH subjects underwent MRI on a 3T clinical scanner with a 32-channel head coil. Scans included anatomic T1- and T2-weighted images and a 3D gradient 8-echo sequence. Seven regions on the contra-lesional hemisphere were segmented using registered T1 and gradient-echo images. R2* maps were generated and the mean values per region were compared to identical regions in normal subjects using a T-test with Bonferroni correction (corrected p = p * 7). Results: 14 IPH patients, aged 18-85, and 10 control subjects, aged 35-73, underwent MRI scanning. Mean R2* varied from 17.8-40.8 Hz in IPH subjects and 19.5-38.4 Hz in normal subjects. There was a significant difference in the mean R2* values in the centrum semiovale (p=2.9e-5). The other regions demonstrate no significant differences in mean R2* values, as shown in the figure. Conclusion: In the contra-lesional centrum semiovale, the average R2* values of IPH patients correlate to lower Fe concentrations compared to controls. Upon further review of anatomic T1- and T2- weighted images, we found that the IPH patients had more white matter T2-hyperintense foci likely accounted for by underlying small vessel disease. In the other brain regions, the contralateral cerebral hemisphere of IPH subjects had R2* values not significantly different from controls. This suggests the Fe released from a hematoma does not cross into the contra-lesional hemisphere, which may be used as an internal control in future longitudinal IPH studies.