Related Experiment Videos
Proton relaxation enhancement by manganese(III)TPPS4 in a model tumor system
Abstract:
Managanese(III)tetraphenylporphine sulfonate [Mn(III)TPPS4] has been investigated as a tumor specific paramagnetic contrast agent for magnetic resonance imaging (MRI) of L1210 solid tumors in mice. Mn(III)TPPS4 was found to clear rapidly from the blood and concentrate in the kidneys, tumor and liver. Although relatively high ratios of tumor to normal tissues could be obtained (e.g., greater than 90 for tumor/muscle), the kidneys were found to have the highest concentration of the metalloporphyrin at all doses and time periods tested. A significant decrease in the longitudinal relaxation time was measured for excised tissues (kidney, tumor, liver, muscle) from mice that were treated with Mn(III)TPPS4. A linear correlation was observed between the longitudinal relaxation rate determined for L1210 tumor and the corresponding concentration of Mn(III)TPPS4 found at various injected doses and time intervals between the injection and analysis. A small animal radiofrequency receiver coil designed for use with a 0.15-T clinical imager was employed to evaluate the ability of Mn(III)TPPS4 to selectively increase the signal intensity of the implanted L1210 tumor. The images show a conspicuous enhancement in the contrast between the tumor and adjacent tissue upon treatment with this agent. The results indicate that Mn(III)TPPS4 is a useful prototype paramagnetic metalloporphyrin MRI contrast agent with a significant affinity for the L1210 tumor.
Insights
Manganese(III)tetraphenylporphine sulfonate (Mn(III)TPPS4) shows promise as a tumor-specific MRI contrast agent. It enhances tumor visibility in L1210 solid tumors in mice, despite high kidney accumulation.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Pharmacology
Background:
- Developing novel contrast agents for magnetic resonance imaging (MRI) is crucial for accurate tumor detection.
- Paramagnetic metalloporphyrins offer potential as targeted imaging agents due to their unique properties.
Purpose of the Study:
- To investigate Manganese(III)tetraphenylporphine sulfonate (Mn(III)TPPS4) as a tumor-specific paramagnetic contrast agent for MRI.
- To evaluate the efficacy of Mn(III)TPPS4 in imaging L1210 solid tumors in mice.
Main Methods:
- Administration of Mn(III)TPPS4 to mice bearing L1210 solid tumors.
- Assessment of Mn(III)TPPS4 biodistribution and tissue concentration.
- Measurement of longitudinal relaxation times in excised tissues.
- Small animal MRI using a 0.15-T clinical imager with a dedicated coil.
Main Results:
- Mn(III)TPPS4 demonstrated rapid blood clearance and concentrated in kidneys, tumors, and liver.
- High tumor-to-normal tissue ratios (e.g., >90 for tumor/muscle) were achieved.
- Significant decreases in longitudinal relaxation times were observed in treated tissues.
- MRI revealed conspicuous contrast enhancement between the L1210 tumor and adjacent tissues.
Conclusions:
- Mn(III)TPPS4 acts as a useful prototype paramagnetic metalloporphyrin MRI contrast agent.
- The agent exhibits significant affinity for L1210 tumors, enhancing their visualization.
- Further research may optimize its use, balancing tumor targeting with potential kidney accumulation.