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Liposome encapsulated MnCl2 as a liver specific contrast agent for magnetic resonance imaging
M R Niesman1, G G Bacic, S M Wright
1Bioacoustics Research Laboratory, University of Illinois, Urbana-Champaign.
Abstract:
We examined the usefulness of MnCl2 entrapped in liposomes as a liver specific contrast agent for magnetic resonance imaging. Toxicity experiments showed that the effective dose for imaging experiments was 7 to 11 times lower than the LD50 of free MnCl2. In rats with implanted liver tumors, liposome encapsulated MnCl2 caused a two- to three-fold increase in the relaxation rate of the liver while having little effect on the relaxation rate of tumor tissue. T1 weighted, magnetic resonance images obtained at 0.5 T of an R3230 adenocarcinoma implanted in the liver showed an increase in the signal intensity of both normal liver and tumor tissue after the injection of free MnCl2 (25 mumole/kg). However, after the injection of liposome encapsulated MnCl2 (40 mumole/kg) the liver exhibited a marked increase in signal intensity with little change in the signal intensity of the tumor tissue. These results suggest that liposome encapsulated MnCl2 has excellent potential as a liver specific contrast agent for the improved detection of liver metastases.
Insights
Liposome-encapsulated manganese chloride (MnCl2) shows promise as a liver-specific MRI contrast agent. This targeted delivery enhances liver signal intensity, aiding in the detection of liver metastases.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Oncology
Background:
- Magnetic resonance imaging (MRI) requires contrast agents for enhanced visualization.
- Developing liver-specific contrast agents is crucial for detecting liver metastases.
- Manganese chloride (MnCl2) has potential as an MRI contrast agent but lacks specificity.
Purpose of the Study:
- To evaluate liposome-encapsulated MnCl2 as a liver-specific contrast agent for MRI.
- To assess the toxicity and efficacy of liposome-encapsulated MnCl2 in preclinical models.
Main Methods:
- Liposome encapsulation of MnCl2 was performed.
- Toxicity studies determined the median lethal dose (LD50) of free and encapsulated MnCl2.
- MRI experiments were conducted on rats with implanted liver tumors using T1-weighted imaging at 0.5 T.
Main Results:
- Liposome-encapsulated MnCl2 demonstrated significantly lower toxicity compared to free MnCl2.
- Encapsulated MnCl2 increased liver relaxation rates (2-3 fold) with minimal effect on tumor tissue.
- MRI showed enhanced liver signal intensity with minimal tumor signal change after liposomal MnCl2 administration.
Conclusions:
- Liposome-encapsulated MnCl2 acts as a liver-specific MRI contrast agent.
- This approach improves the detection of liver metastases by differentiating tumor from healthy liver tissue.
- Further development holds potential for improved liver cancer diagnosis.