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Updated: Aug 12, 2026
MRI-guided Disruption of the Blood-brain Barrier using Transcranial Focused Ultrasound in a Rat Model
Published on: March 13, 2012
MRI study of immediate cell viability in focused ultrasound lesions in the rabbit brain
L Chen1, D M Bouley, B T Harris
1Department of Radiology, Stanford University, Stanford, California 94305-5488, USA. Lili@s-word.stanford.edu
Abstract:
The purpose of this study was to evaluate cell viability in MR imaged focused ultrasound (FUS) lesions using cell-viability staining with triphenyl tetrazolium chloride (TTC) and both light and electron microscopy. Ten paired ultrasonic lesions were created in 5 rabbit brains in vivo with an ultrasound beam of 1.5 MHz electrical power input to the transducer of 50 W and exposure duration of 15 seconds. T2-weighted fast spin-echo (FSE) MRI was performed to detect the FUS lesions in the brain 4 hours after treatment, after which the animals were immediately euthanized. Lesion sizes were measured on TTC-stained specimens, histological sections stained with hematoxylin and eosin (H&E), and T2-weighted MR images. The differences between the lesion diameters measured with the three methods were within the range of 0.1--0.7 mm. The lesion sizes measured from MRI correlated well with those seen from H&E sections. The measurements from MRI slightly overestimated lesion sizes on TTC-stained wet tissues by approximately one MRI pixel (0.31 mm). Electron microscopy demonstrated nuclear and cytoplasmic ultrastructural damage within the grey-white, non-TTC-stained lesion zone, whereas the TTC-stained normal tissue showed preservation of neuronal ultrastructure. Therefore, MR-imaged lesions represent a cell-death zone in rabbit brain 4 hours after FUS ablation, with slight overestimation by approximately one MRI pixel. J. Magn. Reson. Imaging 2001;13:23-30.
Insights
Magnetic Resonance Imaging (MRI) accurately identifies focused ultrasound (FUS) induced cell death zones in rabbit brains. Lesion sizes measured by MRI correlate well with histological methods, showing minimal overestimation.
Area of Science:
- Neuroscience
- Medical Imaging
- Biophysics
Background:
- Focused ultrasound (FUS) is an emerging technology for non-invasive tissue ablation.
- Accurate assessment of FUS-induced lesions is crucial for therapeutic applications.
- Magnetic Resonance Imaging (MRI) offers potential for real-time lesion monitoring.
Purpose of the Study:
- To evaluate the accuracy of MRI in assessing cell viability within FUS-induced lesions.
- To compare MRI-based lesion measurements with histological and cell-viability staining methods.
- To characterize ultrastructural changes in FUS-ablated brain tissue using electron microscopy.
Main Methods:
- Focused ultrasound (FUS) lesions were created in rabbit brains in vivo.
- T2-weighted fast spin-echo (FSE) MRI was performed 4 hours post-treatment.
- Cell viability was assessed using triphenyl tetrazolium chloride (TTC) staining.
- Histological analysis included hematoxylin and eosin (H&E) staining.
- Light and electron microscopy were used for ultrastructural examination.
Main Results:
- Lesion sizes measured by MRI, H&E, and TTC staining showed good correlation (0.1–0.7 mm difference).
- MRI measurements slightly overestimated lesion size on TTC-stained tissue by approximately one MRI pixel (0.31 mm).
- Electron microscopy revealed significant ultrastructural damage in the non-TTC-stained lesion zone.
- Normal brain tissue stained with TTC showed preserved neuronal ultrastructure.
Conclusions:
- MR-imaged lesions in rabbit brains represent a cell-death zone 4 hours after FUS ablation.
- MRI provides a reliable method for lesion size assessment, with minor overestimation.
- These findings support the use of MRI for monitoring FUS treatments in the brain.
