Tracers in vascular casting resins enhance backscattering brightness
Article first published online: 6 DEC 2006
Copyright © 2002 Wiley Periodicals, Inc.
Volume 24, Issue 3, pages 121–126, May/June 2002
How to Cite
Schraufnagel, D. E. and Ganesan, D. P. (2002), Tracers in vascular casting resins enhance backscattering brightness. Scanning, 24: 121–126. doi: 10.1002/sca.4950240303
- Issue published online: 6 DEC 2006
- Article first published online: 6 DEC 2006
- Manuscript Accepted: 10 DEC 2001
- Manuscript Received: 25 JUN 2001
- corrosion casting;
- scanning electron;
- pulmonary circulation
Studying cast microvasculature with scanning electron microscopy has expanded our knowledge of many circulations, but need arises to determine the blood source of vascular beds that are supplied by two circulations. One way to do this is to mark the casting resin by adding a tracer compound that can be detected in the scanning electron microscope. A potential method of distinguishing different substances is to detect the backscattered electrons that are emitted from the tracer if the tracer is a heavier element, because heavier elements backscatter more electrons. To explore different tracers, we tested lead, titanium, iron, osmium, and uranium as solutions of different polarity and powders. The tracers were added to 1 ml of methyl methacrylate in log concentrations. Shrinkage, hardness, cast quality, and change in brightness from the tracer were compared with multivariate analysis at scanning electron microscopic working distances of 15 and 39 mm on carbon-coated and uncoated specimens. Several concentrations caused sedimentation of the tracer and prevented the resin from solidifying. Tetraethyl lead shortened the hardening time; uranyl acetate and osmium tetroxide prolonged it. Most tracers decreased shrinkage. When lead citrate and Reynolds solutions were removed, the brightness correlated with increasing atomic number, concentration of the tracer, and mean atomic number of the specimen (p <0.0001). The substances that increased contrast most were tetraethyl lead and uranium. Backscattering electron detection can distinguish methacrylate casts that have small amounts of heavier elements added to them, but an optimal tracer has not yet been established.