Radiolabelling of erythrocytes with 18FDG : feasibility study
5 October 2022J. Costes, J. Delage, K. Casagrande, J. Prior, F. Sadeghipour
HU de Lausanne, Suisse
The radiolabelling of the erythrocytes is performed to carry out scintigraphies for various indications: ectopic spleen or digestive haemorrhage detection. These preparations are done with 99mTc but these examinations have shown limitations in sensitivity in case of minor digestive haemorrhages. The use of a PET tracer would allow much better sensitivity and imaging resolution. Thus, we developed the radiolabelling of erythrocytes by 18F.
Material and method
10 mL of blood were collected from healthy fasting volunteers (n = 3). Blood cells were isolated by 2 cycles of centrifugation. Then, cells were incubated with about 350 MBq of 18FDG for 20 minutes at 37°C. Free 18FDG was removed by 1 cycle of centrifugation. Radiolabelling efficiency and free 18FDG were calculated at the end of labelling. The cell viability was checked by microscopic examination and the stability was assessed 2h after radiolabelling by measuring the free 18FDG. The dosimetry exposition of the operator was measured for whole body and extremities.
Results and discussion
The mean duration of the process was 80 minutes. The radiolabelling efficiency was 40.6 ± 11% and the free 18FDG rate was 51.8 ± 5.2%. The cell viability at the end of labelling was > 99% and the 18FDG release at 2h after labelling was 4.6 ± 0.1%. The dosimetric exposition of the operators for the whole body and the extremities were respectively 13 ± 4.2 µSv and 33.9 ± 13.5 µSv.
The radiolabelling efficiency can be improved by optimization of the labelling conditions (volume of blood withdrawn, labelling activity, incubation duration…). This method allows obtaining a sufficient final activity with respect of the cell integrity and a final suspension cells with a good stability. The dosimetric exposition of the operator is limited and can be reduced by improving the radioprotection of the equipment (centrifuge, heater…). The activity to be injected will be determined by dosimetric characterization.
The radiolabelling of the erythrocytes with 18FDG allows new diagnosis perspectives for the detection of digestive haemorrhage detection or ectopic spleen when scintigraphy can have a lack of sensitivity and a low imaging resolution.