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Imaging Cerebral Microhemorrhages in Military Service Members with Chronic Traumatic Brain Injury
Wei Liu1, Karl Soderlund1, Justin S Senseney1
1From the National Intrepid Center of Excellence (NICoE), Walter Reed National Military Medical Center, 4860 S Palmer Rd, Bethesda, MD 20889-5649 (W.L., K.S., J.S.S., D.J., P.H.Y., J.O., E.B.S., T.R.O., G.R.); Center for Neuroscience and Regenerative Medicine, Bethesda, Md (D.J., T.R.O., G.R.); The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Md (D.J.); Biomedical Engineering Department, Cornell University, New York, NY (T.L., Y.W.); and The NorthTide Group, Sterling, Va (W.L., E.B.S.).
Purpose:
To detect cerebral microhemorrhages in military service members with chronic traumatic brain injury by using susceptibility-weighted magnetic resonance (MR) imaging. The longitudinal evolution of microhemorrhages was monitored in a subset of patients by using quantitative susceptibility mapping.
Materials And Methods:
The study was approved by the Walter Reed National Military Medical Center institutional review board and is compliant with HIPAA guidelines. All participants underwent two-dimensional conventional gradient-recalled-echo MR imaging and three-dimensional flow-compensated multiecho gradient-recalled-echo MR imaging (processed to generate susceptibility-weighted images and quantitative susceptibility maps), and a subset of patients underwent follow-up imaging. Microhemorrhages were identified by two radiologists independently. Comparisons of microhemorrhage number, size, and magnetic susceptibility derived from quantitative susceptibility maps between baseline and follow-up imaging examinations were performed by using the paired t test.
Results:
Among the 603 patients, cerebral microhemorrhages were identified in 43 patients, with six excluded for further analysis owing to artifacts. Seventy-seven percent (451 of 585) of the microhemorrhages on susceptibility-weighted images had a more conspicuous appearance than on gradient-recalled-echo images. Thirteen of the 37 patients underwent follow-up imaging examinations. In these patients, a smaller number of microhemorrhages were identified at follow-up imaging compared with baseline on quantitative susceptibility maps (mean ± standard deviation, 9.8 microhemorrhages ± 12.8 vs 13.7 microhemorrhages ± 16.6; P = .019). Quantitative susceptibility mapping-derived quantitative measures of microhemorrhages also decreased over time: -0.85 mm(3) per day ± 1.59 for total volume (P = .039) and -0.10 parts per billion per day ± 0.14 for mean magnetic susceptibility (P = .016).
Conclusion:
The number of microhemorrhages and quantitative susceptibility mapping-derived quantitative measures of microhemorrhages all decreased over time, suggesting that hemosiderin products undergo continued, subtle evolution in the chronic stage.
Insights
Cerebral microhemorrhages in military service members with chronic traumatic brain injury decrease over time. Quantitative susceptibility mapping reveals subtle, ongoing evolution of these lesions in the chronic stage.
Area of Science:
- Neuroimaging
- Radiology
- Traumatic Brain Injury Research
Background:
- Chronic traumatic brain injury (TBI) is a significant concern in military service members.
- Cerebral microhemorrhages are potential indicators of TBI severity and long-term effects.
- Advanced magnetic resonance (MR) imaging techniques are crucial for detecting subtle brain abnormalities.
Purpose of the Study:
- To detect cerebral microhemorrhages in military service members with chronic TBI.
- To monitor the longitudinal evolution of microhemorrhages using quantitative susceptibility mapping (QSM).
Main Methods:
- Susceptibility-weighted imaging (SWI) and quantitative susceptibility mapping (QSM) were employed.
- Two radiologists independently identified microhemorrhages.
- Paired t-tests were used to compare microhemorrhage characteristics at baseline and follow-up.
Main Results:
- Cerebral microhemorrhages were detected in 43 of 603 patients.
- Microhemorrhages appeared more conspicuous on SWI compared to gradient-recalled-echo images.
- A significant decrease in the number and volume of microhemorrhages was observed over time on QSM (P = .019 for number, P = .039 for volume).
Conclusions:
- The number and quantitative measures of cerebral microhemorrhages decrease over time in chronic TBI.
- This suggests continued, subtle evolution of hemosiderin products in the chronic stage of TBI.
- QSM is a valuable tool for assessing the longitudinal changes in microhemorrhages.
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