Ultratag® RBC Kit for Combined Cardiac First-Pass and Multigated Acquisition Studies

Abstract

The authors developed a procedure to use the in vitro Ultratag® (Mallinckrodt, St. Louis, MO) red blood cell (RBC) labeling kit for both first-pass (FP) and multigated acquisition (MUGA) studies with a high specific activity in a reduced volume (50 mCi/0.5 ml) and a high labeling efficiency that can be used with a single-crystal camera to yield a quality study.

Methods: A packed red blood cell (PRBC) bolus was created by two methods: (a) reducing the volume of the components of the Ultratag® kit and (b) centrifuging the final dose volume. The labeling efficiency of each bolus was evaluated, each PRBC bolus was visually inspected for clots and percent hemolysis was assessed using a hemocytometer at 30 min, 1 hr and 2 hr postcentrifugation.

Results: Use of the first method, the 50% kit, provided the best results. However, the resulting volume from this kit only approached 1 ml, which is not clinically adequate for a first-pass study. In the second method, the total volume was centrifuged to form a PRBC bolus, which appeared to be stable in the syringe for at least 2 hr. 3A combined FP/MUGA study from a centrifuged 50% reduced kit was performed in one normal subject as a preliminary assessment of the clinical utility of this procedure. The image quality of the scan is diagnostically adequate.

Conclusion: By using the in vitro Ultratag® kit, a compact PRBC bolus was created that was stable in the syringe and could be reinjected safely into the patient for combined cardiac FP/MUGA studies.