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Diffusion- and T2-weighted MRI of closed-head injury in rats: a time course study and correlation with histology
Y Assaf1, E Beit-Yannai, E Shohami
1School of Chemistry, Tel Aviv University, Ramat Aviv, Israel.
Abstract:
Diffusion- and T2-weighted MRI were used to evaluate changes in brain water characteristics following closed-head injury in rats. Images were collected within the first 2 h and at 24 h and 7 days following the traumatic event and then compared with histology. The ratios between the apparent diffusion coefficients (ADCs) of the traumatized tissues and normal brain tissues were significantly different from unity and were found to be 0.79 +/- 0.25 (p < 0.01), 0.49 +/- 0.33 (p < 0.0002), and 3.47 +/- 1.36 (p < 10(-6)) at 1-2 h, 24 h, and 1 week after the trauma, respectively. In severe trauma, areas of hyperintensity which were not apparent on the T2-weighted images could be detected on the diffusion-weighted images within 1-2 h after the trauma. At 24 h following the traumatic event, large areas of hyperintensity are observed in both types of images. One week following the trauma, the ADCs of the traumatized tissues (1.84 +/- 0.69 x 10(-5) cm2/s) are much larger than those of normal brain (0.57 +/- 0.19 x 10(-5) cm2/s) and approach the value of free water. At 7 days, the areas of hyperintensity in the T2-weighted images seem to underestimate the injured areas found by histology. At this time point a good correlation is obtained between the areas of hypointensity observed on the diffusion-weighted images and the infarct areas obtained by histology (r = 0.88).
Insights
Diffusion-weighted MRI reveals early brain water changes after head injury in rats, with apparent diffusion coefficients (ADCs) correlating with injury severity and histology by one week post-trauma.
Area of Science:
- Neuroimaging
- Biophysics
- Traumatic Brain Injury Research
Background:
- Closed-head injury in rats causes significant changes in brain water characteristics.
- Understanding these changes is crucial for diagnosing and managing traumatic brain injury (TBI).
Purpose of the Study:
- To evaluate changes in brain water characteristics using diffusion- and T2-weighted MRI after closed-head injury in rats.
- To compare MRI findings with histological data at various time points post-trauma.
Main Methods:
- Diffusion- and T2-weighted MRI scans were performed on rats at 1-2 hours, 24 hours, and 7 days post-injury.
- Apparent Diffusion Coefficients (ADCs) were calculated and compared between traumatized and normal brain tissues.
- MRI results were correlated with histological findings.
Main Results:
- Apparent Diffusion Coefficients (ADCs) showed significant deviations from normal values, indicating altered brain water content at all time points.
- Diffusion-weighted imaging detected injury-related hyperintensities earlier than T2-weighted imaging, especially in severe trauma cases.
- At 7 days, ADCs in injured tissues approached free water values, and diffusion-weighted imaging hypointensities strongly correlated with histological infarct areas (r=0.88).
Conclusions:
- Diffusion-weighted MRI is a sensitive tool for detecting early brain water changes following TBI.
- ADC values and diffusion-weighted imaging findings provide valuable insights into TBI severity and progression.
- Diffusion-weighted MRI demonstrates strong correlation with histological outcomes, particularly for infarct detection at 7 days post-injury.