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Effect of ionic and nonionic contrast media on regional distribution of thallium-201 in rabbits
H Seto1, M Kageyama, M Shimizu
1Department of Radiology, Toyama Medical and Pharmaceutical University, Japan.
Insights
Contrast media administration alters regional blood flow distribution in rabbits. Ionic contrast media caused more significant changes in blood flow to the heart, leg muscles, and liver compared to nonionic contrast media.
Area of Science:
- Radiology and Imaging
- Cardiovascular Physiology
- Pharmacology
Background:
- Regional blood flow is crucial for organ function and is modulated by vascular resistance.
- Thallium-201 (201Tl) distribution serves as a reliable indicator of fractional cardiac output and regional blood flow.
- While contrast media side effects are known, simultaneous assessment of regional blood flow changes post-administration is lacking.
Purpose of the Study:
- To investigate the impact of iodinated contrast media on regional blood flow distribution in rabbits.
- To compare the effects of ionic and nonionic contrast media on organ-specific blood flow.
Main Methods:
- Utilized a double-dose thallium-201 (201Tl) method to estimate regional blood flow changes.
- Compared 201Tl distribution in rabbits administered nonionic (Iohexol) and ionic (Iothalamate) contrast media against a control group.
- Validated 201Tl distribution against 99mTc-MAA in control animals for key organs (heart, spleen, kidneys, leg muscles).
Main Results:
- A significant increase in 201Tl distribution was observed in the heart and leg muscles in both contrast media groups.
- A significant decrease in 201Tl distribution was noted in the liver for both contrast media groups.
- No significant changes in renal or intestinal blood flow were detected in any group.
Conclusions:
- Intravenous contrast media administration leads to uneven redistribution of regional blood flow in rabbits.
- The observed blood flow alterations primarily affect the heart, leg muscles, and liver.
- Ionic contrast media induced more pronounced regional blood flow redistribution compared to nonionic contrast media.
Abstract:
Cardiac output is effectively redistributed to each part of the body by regional changes in vascular resistance. Thallium-201 distribution reflects the fractional distribution of cardiac output and parallels regional blood flow. The side effects of iodinated contrast media in different organs have been well documented in animal experiments and clinical studies. However, no simultaneous assessment of regional blood flow change in each part of the body after the administration of contrast media has been reported. Using a double-dose thallium-201 method, we investigated the effect of contrast media on the regional distribution of thallium-201 in each organ as an estimate of regional blood flow change in rabbits. The distribution of 201T1 and 99mTc-MAA was similar in the heart, spleen, kidneys, and leg muscles in the control animals (r = 0.99). The regional distribution of thallium-201 significantly increased in the heart and leg muscle, but decreased in the liver in the nonionic (Iohexol) and ionic (Iothalamate) contrast medium groups as compared with the control group. There were no significant changes in the kidneys or intestine in these three groups in our study. The intravenous infusion of contrast media in rabbits causes uneven redistribution of regional blood flow in the heart, leg muscle and liver. These changes are more prominent in the ionic contrast medium group.