Rapid quantitative susceptibility mapping of intracerebral hemorrhage

Objective: To serially quantify changes of iron concentration within hematomas in the intracerebral hemorrhage (ICH) pig model using non-invasive R2* and quantitative susceptibility mapping (QSM) MRI methods. Introduction: Hemolysis-related release of hemoglobin/heme/free iron after ICH causes cytotoxic injury. An accurate post hemorrhage assessment of iron would be valuable to develop strategies to prevent secondary damage. The T2* relaxation rate (R2* =1/T2*) on MRI depends on the regional oxy- versus deoxyhemoglobin. Post-ICH excess of deoxyhemoglobin has been applied as a quantitative marker to estimate iron in the brain. However, quantitative susceptibility mapping (QSM) is a new MRI technique that can quantify iron concentration within the hematoma by measuring induced magnetic susceptibility. Using R2* mapping and QSM in a large animal ICH model, we measured spatiotemporal changes in iron concentration in the brain. Methods: Lobar ICH was induced by infusion of 2.5 ml autologous blood in 8 Yorkshire pigs with average age/wt of 4-6wk/12.5±2.5kg. MRI was obtained at days 1 and 7. A 3D anatomical and multi-echo gradient echo images were obtained on a clinical 3.0 T Philips Ingenia MRI system. Parametric R2* and susceptibility maps were generated. Regions of interest were placed within hematoma and contralesional CSF. Results: R2* measurements in the hematoma at day 1 and day 7 were 41.3 ± 7.3 and 37.7 ± 7.7 s -1 , respectively, whereas the corresponding susceptibility measurements were 0.75± 0.3 and 0.70 ± 0.5 ppm. The CSF R2* were 5.53 ± 2.1 and 6.85 ± 2.4 s -1 , whereas susceptibility showed 0.06 ± 0.16 and 0.02 ± 0.03 ppm at the two time points. Both R2* and QSM showed no significant change in iron concentration within the hematoma ROI with p-value of 0.18 and 0.72 over a week. Absence of hyperintense regions remote from the hematoma in susceptibility maps suggested lack of diffuse iron deposition. Good correlation was observed between R2* and QSM (correlation coefficient 0.83 and 0.78 within hematoma, and -0.66 and -0.07 within CSF, at day 1 and 7, respectively). Conclusion: R2* and especially QSM, with their ability to provide quantitative iron content, are valuable tools to test new ICH treatments particularly targeting iron in this large animal model.

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

Stroke ◽

10.1161/str.44.suppl_1.awp292 ◽

2013 ◽

Vol 44 (suppl_1) ◽

Author(s):

Shuo Wang ◽

Min Lou ◽

Tian Liu ◽

xiaomei chen ◽

Yi Wang

Keyword(s):

Intracerebral Hemorrhage ◽

T2 Mapping ◽

Volume Measurement ◽

Susceptibility Mapping ◽

Gradient Echo ◽

Hematoma Volume ◽

Quantitative Susceptibility Mapping ◽

Voxel Size ◽

Magnitude Image ◽

Imaging Parameters

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.

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Serial quantitative neuroimaging of iron in the intracerebral hemorrhage pig model

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x17751548 ◽

2018 ◽

Vol 38 (3) ◽

pp. 375-381 ◽

Cited By ~ 10

Author(s):

Muhammad E Haque ◽

Refaat E Gabr ◽

Xiurong Zhao ◽

Khader M Hasan ◽

Andrew Valenzuela ◽

...

Keyword(s):

Intracerebral Hemorrhage ◽

Brain Damage ◽

Autologous Blood ◽

Susceptibility Mapping ◽

Pig Model ◽

Quantitative Susceptibility Mapping ◽

Autologous Blood Injection ◽

Blood Injection ◽

Quantitative Neuroimaging ◽

The Brain

Iron released after intracerebral hemorrhage (ICH) is damaging to the brain. Measurement of the content and distribution of iron in the hematoma could predict brain damage. In this study, 16 Yorkshire piglets were subjected to autologous blood injection ICH model and studied longitudinally using quantitative susceptibility mapping and R2* relaxivity MRI on day 1 and 7 post-ICH. Phantom calibration of susceptibility demonstrated (1) iron distribution heterogeneity within the hematoma and (2) natural absorption of iron from 154 ± 78 µg/mL (day 1) to 127 ± 33 µg/mL (day 7). R2* in the hematoma decreased at day 7. This method could be adopted for ICH in humans.

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