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Studies on bromobenzene-induced hepatotoxicity using in vivo MR microscopy with surgically implanted RF coils
X Zhou1, R R Maronpot, G P Cofer
1Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710.
Abstract:
Using surgically implanted RF coils at 300 MHz, three-dimensional microscopic MR images of rat liver were obtained in vivo to follow the development of pathology induced by bromobenzene exposure. Formalin fixed specimens of liver from these animals were also imaged using in vitro MR microscopy, followed by conventional optical microscopy. All MR images were acquired using a spin-warp pulse sequence with TR = 950 ms and TE = 23 ms. The in vivo images were reconstructed as 256(2) x 32 arrays with a voxel size of (50 microns)2 x 219 microns, while the in vitro images were reconstructed as 256(2) x 128 arrays, giving an isotropic resolution at (39 microns)3. Based on results from six animals, we have found in all animals exposed to bromobenzene, image intensity decreased in specific hepatic tissue regions. These regions were well correlated to low signal intensity areas observed in in vitro MR images at higher resolution. Conventional optical microscopy indicated that the low signal intensity regions corresponded to areas of necrosis. The decrease in signal intensity is consistent with increased local diffusion coefficients as a result of necrosis. This study demonstrates that MR microscopy with implanted RF coils can be successfully used to follow tissue pathological changes in living tissues.
Insights
Magnetic resonance (MR) microscopy with implanted radiofrequency (RF) coils successfully tracked liver pathology in rats. This technique identified necrotic regions in vivo, correlating with higher-resolution ex vivo MR microscopy and optical microscopy findings.
Area of Science:
- Biomedical Imaging
- Pathology
- Toxicology
Background:
- Bromobenzene exposure induces liver pathology.
- In vivo imaging is crucial for monitoring dynamic pathological changes.
- MR microscopy offers high-resolution imaging capabilities.
Purpose of the Study:
- To evaluate the utility of in vivo MR microscopy for tracking bromobenzene-induced liver pathology in rats.
- To correlate in vivo MR findings with ex vivo MR microscopy and conventional optical microscopy.
- To investigate the relationship between MR signal intensity changes and tissue necrosis.
Main Methods:
- Surgically implanted RF coils were used for in vivo 3D MR microscopy of rat livers at 300 MHz.
- Spin-warp pulse sequences (TR=950 ms, TE=23 ms) were employed for image acquisition.
- In vitro MR microscopy and conventional optical microscopy were used for ex vivo analysis.
Main Results:
- In vivo MR images revealed decreased signal intensity in specific hepatic regions following bromobenzene exposure.
- These regions correlated with low signal areas in higher-resolution in vitro MR images.
- Optical microscopy confirmed these areas corresponded to hepatic necrosis.
Conclusions:
- In vivo MR microscopy with implanted RF coils can effectively monitor the development of liver pathology.
- Decreased MR signal intensity in necrotic regions is likely due to increased local diffusion coefficients.
- This technique provides a valuable tool for studying dynamic pathological processes in living tissues.