Efficiency of labelling of red blood cells with technetium-99m after dipyridamole infusion for thallium-201 stress testing

Abstract

Experimental studies have suggested that dipyridamole may inhibit red blood cell labelling with technetium-99m. To evaluate whether this effect is clinically relevant to the performance of radionuclide ventriculography after dipyridamole-thallium stress testing, in vitro red blood cell labelling was compared immediately before and after thallium-201 stress scintigraphy combined with either dipyridamole infusion (30 patients) or exercise stress (20 patients). Modified in vivo red blood cell labelling efficiency was assessed in a further 36 patients following dipyridamole infusion and was compared with that in 15 patients following exercise stress. The importance of a reversal of the dipyridamole effects by aminophylline was evaluated for in vitro and modified in vivo techniques. The red blood cell labelling efficiency was not significantly different in patients following dipyridamole compared with that obtained following exercise stress for both in vitro (93% +/- 4% versus 91% +/- 4%) and modified in vivo (87% +/- 19% versus 90% +/- 6%) techniques. Also, in vitro red blood cell labelling efficiency after dipyridamole was not different to that before stress testing (93% +/- 4% versus 92% +/- 4%). Reversal with aminophylline had no significant effect on the in vitro labelling efficiency with either the in vitro technique (94% +/- 3% with reversal versus 92% +/- 5% without) or the modified in vivo technique (91% +/- 4% with reversal versus 82% +/- 26% without). These results suggest that the red blood cell labelling efficiency is not compromised by the preceding dipyridamole-thallium stress testing but can be optimised by using in vitro labelling.

Technetium-99m labelled human serum albumin for ventriculography: a comparative evaluation of six labelling kits

“…Therefore, in most departments 99mTc-HSA has been replaced by 99mTc-labelled red blood cells (99mTc-RBCs), which have a much longer half-life in the blood. Ideally, in vitro labelled erythrocytes should be used [5,6] but their preparation is time consuming and involves some serious risks such as a possible transfer of viral infections to the manipulator in the case of skin prick accidents. The possibility of administration of the labelled RBCs to the wrong patient is another major risk, especially in departments with a high patient flow.…”

“…HPLC chromatograms of 99mTc-HSA preparations reconstituted from kit B and kit E. Peak with Rt = 9.4 min: component with high molecular mass (1); R t = 12.5rain and 13.7 min: polymerized albumin fractions (2 and 3); Rt=15.4 min: monomeric albumin (4); R t = 18.9 min: component with low molecular mass (5); Rt = 25.0 rain: pertechnetate(6) …”

Poor-quality red blood cell labelling with technetium-99m: case report and review of the literature

“…Cytotoxic, immunosuppressive and antibiotic medications [14] In addition to the above list, dipyridamole has been shown experimentally to inhibit RBC labelling with 99~I'c [15]. In contrast to this, Hicks et al [16] have recently reported a clinical study which suggested that dipyridamole does not adversely affect RBC labelling with 99r~c in clinical practice.…”

Influence of biflorin on the labelling of red blood cells, plasma protein, cell protein, and lymphocytes with technetium-99m: in vitro study

“…The interactions between radiopharmaceuticals and other drugs is an important factor that has received a lot of attention from researchers -these interactions can change the chemical nature of the radiotracer and the biochemical medium of the target, or can interfere in the radiotracer's binding to plasma proteins and/or blood cells (Hladik III;Saha, 1987;Srivastava;Straub, 1990;Sampson, 1996). This may result in the radiopharmaceutical's incorrect biodistribution, leading to imprecise diagnosis, repetitive exams, and patients' unnecessary exposure to radiation (Hladik III;Saha, 1987;Hicks;Arkles, 1992;Kelly et al, 1992;BernardoFilho et al, 1994;Santos et al, 1995;Eising;Reiners, 1998).…”