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Updated: Aug 11, 2026
Micro-particle Image Velocimetry for Velocity Profile Measurements of Micro Blood Flows
Published on: April 25, 2013
Fluorescent microspheres are superior to radioactive microspheres in chronic blood flow measurements
M F Van Oosterhout1, F W Prinzen, S Sakurada
1Department of Physiology, Cardiovascular Research Institute Maastricht, University of Maastricht, 6200 MD Maastricht, The Netherlands.
Abstract:
The accuracy of the fluorescent (FM) and radioactive microsphere (RM) techniques is similar in acute experiments but has not been established in chronic experiments. In the present study various combinations (at least pairs) of FM and/or RM labels were injected simultaneously between 2 mo and 5 min before each animal was killed. Blood flow was determined in many organs. Intramethod mean difference and variation did not change over time for FM but increased significantly for RM (from 1.8 +/- 1.4 to 25.6 +/- 21.8% and from 4.4 +/- 3.2 to 32.4 +/- 23.0% at 5 min and 2 mo, respectively). Also the FM-RM intermethod mean difference and variation increased (from -0.5 +/- 8.5 to 40.8 +/- 23.8% and from 23. 6 +/- 4.6 to 71.8 +/- 34.3%, respectively). After 2 mo, blood flow estimations were 20-50% lower with the various RM, whereas brain and liver blood flow values varied even more between isotopes. Underestimation started within 1 day for 51Cr and within 2 wk for 141Ce, 95Nb, and 85Sr. We conclude that FM are superior to RM for blood flow determination in experiments lasting longer than 1 day, presumably because of leaching of isotopes from RM.
Insights
Fluorescent microspheres (FM) are more accurate than radioactive microspheres (RM) for long-term blood flow determination. RM accuracy significantly decreases over time due to isotope leaching, impacting experimental results.
Area of Science:
- Physiology
- Biomedical Engineering
- Radiochemistry
Background:
- Accurate measurement of organ blood flow is crucial in physiological and biomedical research.
- Fluorescent microsphere (FM) and radioactive microsphere (RM) techniques are commonly used for blood flow determination.
- The comparative accuracy of FM and RM in chronic experiments remains incompletely understood.
Purpose of the Study:
- To evaluate and compare the accuracy and reliability of fluorescent microsphere (FM) and radioactive microsphere (RM) techniques for determining organ blood flow in chronic experimental settings.
- To assess the impact of experimental duration on the precision of both FM and RM methods.
Main Methods:
- Simultaneous injections of paired fluorescent (FM) and/or radioactive (RM) labels were administered to animals.
- Blood flow was quantified in multiple organs across a time course ranging from 5 minutes to 2 months post-injection.
- Intramethod and intermethod differences and variations were statistically analyzed over time.
Main Results:
- Intramethod variation for FM remained stable over time, while RM showed a significant increase (up to 32.4 +/- 23.0% at 2 months).
- Intermethod differences between FM and RM also increased substantially with duration (up to 40.8 +/- 23.8% at 2 months).
- RM consistently underestimated blood flow by 20-50% after 2 months, with significant variations observed between different RM isotopes and organs.
Conclusions:
- Fluorescent microspheres (FM) demonstrate superior accuracy and stability compared to radioactive microspheres (RM) for blood flow measurements in experiments exceeding 1 day.
- The observed underestimation and increased variability with RM are likely attributable to isotope leaching from the microspheres over extended periods.
- FM technology is recommended for chronic studies requiring precise and reliable organ blood flow quantification.
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