Radiolabeled microsphere method

A second approach to the estimation of rCBF with PET is analogous to the radiolabeled microsphere method employed in laboratory animals... 

Radiolabeled Microsphere Technique. Measurement of blood flow has become an integral part of the physiologic study of humans. While many methods have been utilized in measuring tissue blood flow, the one most often practiced today is dependent on injection of radioactively labeled microspheres. The reason for its overwhelming acceptance is due, in part, to the shortcomings of many of the alternative methods of blood flow determination. 

An interesting new approach to DNA detection involves probes attached to polymer microspheres loaded with a scintil-lant (25). The hybridization of a complementary, radiolabeled target DNA leads to strong signal amplification because of the close proximity of the scintillant and the radiolabel. Another appealing aspect of this method is that the PNA probe can be synthesized directly on the scintillant-loaded microspheres. 

In the measurement of pulmonary perfusion, Ga-labeled albumin microspheres have been used extensively [79]. Pulmonary perfusion involves vascular injection of labeled microspheres sized such that they will be mechanically trapped by the first capillary bed they encounter [80]. Previously, a commercial albumin microsphere kit (3M Instant Microspheres) was used in the preparation of Ga microspheres however, this product has been discontinued. Methods were developed to radiolabel macroaggregated human serum albumin (HSA) with Ga using a lyophilized Technescan MAA kit (Mallinckrodt Inc.) [25,33]. 

---