E-Z TRAC® Colored Ultraspheres For Measuring Regional Blood Flow

EZ-TRAC Colored Microspheres provide the research scientist with an alternative to the use of radioactive microspheres for the measurement of blood flow in experimental animals. The high equipment and disposal costs normally associated with radioactive spheres are eliminated with the E-Z TRAC non-radioacrive colored microspheres. The required laboratory equipment consist of minimal glassware, a multipurpose centrifuge, a hemacytometer counting slide and a microscope. The investigator now has a low cost method for measuring regional blood flow.

Rapid Identification

The E-Z TRAC colored microspheres are crossed linked polystyrene-divinylbenzene microspheres which have been labeled with seven distinct colors: red, blue, orange, green, yellow, black and brown. The high dye content of each individual microsphere allows rapid identification and discrimination under microscope visualization. The colored microspheres are chemically stable and exhibit no dye leaching in aqueous environments, including strong acid and base solutions. Each color of microsphere is available in a wide range of sizes, from 3um diameter to 200 um diameter.

Ubiquitous Preparation

The method of animal preparation and microsphere injection with the E-Z TRAC colored microspheres are the same as that followed with radioactive microspheres in blood flow studies. To measure regional myocardial blood flow, for example, the microspheres are injected into the left atrium of the experimental animal. The E-Z TRAC colored microspheres will mix with the arterial blood and flow with it, will distribute the tissue, and will ultimately lodge in the microvasculture. The number of microspheres in the myocardial tissue of interest and in the reference blood samples are determined by following an extraction procedure using reagents and instructions supplies by E-Z TRAC.

Feasiblilty of Non-Radioactive Microspheres

The feasibility of nonradioactive microspheres for blood flow research has been demonstrated by previous studies using black nonradioactive microspheres and alkaline hydrolysis of tissue and blood samples. The lack of additional colors limited these studies to only one blood measurement for a single diameter of microsphere. Employing the multiple colors of E-Z TRAC microspheres blood flow studies may now consist of up to seven sequential measurements.

The use of labeled microspheres is crucial in experimental studies of organ blood flow distribution, cardiac output distribution, organ ischemia and reperfusion. The standard measurement technique using radioactive microspheres prevents their use at institutions not able to dispose nor afford the cost of radioactive waste. Simultaneous blood flow measurements following coronary artery occlusion with 11.1 um diameter radioactive microspheres and 11.9 um diameter E-Z TRAC colored microspheres have shown a correlation in the measurement of regional myocardial blood flow of r = 0.98. With the availability of E-Z TRAC non radioactive microspheres in seven colors and a range of sizes, institutions are no longer prevented from conduction such research.



1. Maxwell, L.C., et al, Am. J. Physiol., 248, H217(1985).

EZ-TRAC™ Colored Ultraspheres For Measuring Regional Blood Flow Protocol .pdf


Non-Radioactive Blood Flow Investigation

IMT, a leading innovator of non-radioactive microsphere products, introduces the next generation of solutions for safe, rapid regional blood flow investigation available today The NuFlow™ Fluorescent Microsphere System.

NuFlow™ Fluorescent Microspheres


What is NuFlow™?

NuFLOW™ represents a complete system of products aimed at high volume, critical sensitivity investigations of blood flow using safe, inexpensive non-radioactive methods. The key to RBF productivity is increased sample output, reproducible and error-free microsphere extraction and fast, accurate bead counting. Years of experience assisting investigators to process E-Z Trac® color Ultraspheres in conjunction with the acclaimed Investigator Partner Service has enabled IMT to develop the next generation of advancement in blood flow measurement.

Flow Cytometer Analysis Provides

  • Fast Accurate Measurement
  • Easy Sample Preparation
  • Safe and Non-Radioactive
  • The Ability to Analyze both for Microsphere Color & Size

Why NuFlow Fluorescent Microspheres?

It’s no secret that there are other fluorescent microspheres available on the market. NuFlow is unique from many competitor microspheres in that the counting methods employed by Interactive Medical Technologies allow for <0.1% overlap between any two colors. Additionally, we do not measure the fluorescence but count the microspheres directly so that there is no need to measure dye leaching or fading.

NuFLOW™ Fluorescent Microsphere Extraction Protocol .pdf