PET/CT of the Spleen with Gallium-Oxine-Labeled, Heat-Damaged Red Blood Cells: Clinical Experience and Technical Aspects

Abstract

Several scintigraphic techniques have been supplemented or replaced by PET/CT methods because of their superior sensitivity, high resolution, and absolute activity quantification capability. The purpose of this project was the development of a PET tracer for splenic imaging, its radiopharmaceutical validation, and its application in selected patients in whom unclear constellations of findings could not be resolved with established imaging methods. Heat-damaged red blood cells (RBCs) were labeled with [68Ga]gallium-oxine, which was produced from [68Ga]gallium and 8-Hydroxyquinoline (oxine) on an automated synthesizer. Ten patients underwent [68Ga]gallium-oxine-RBC-PET/CT for the classification of eleven unclear lesions (3 intra-, 8 extrapancreatic). [68Ga]gallium-oxine and [68Ga]gallium-oxine-labeled RBCs could be synthesized reproducibly and reliably. The products met GMP quality standards. The tracer showed high accumulation in splenic tissue. Of the 11 lesions evaluated by PET/CT, 3 were correctly classified as non-splenic, 6 as splenic, 1 as equivocal, and 1 lesion as a splenic hypoplasia. All lesions classified as non-splenic were malignant, and all lesions classified as splenic did not show malignant features during follow-up. PET/CT imaging of the spleen with [68Ga]gallium-oxine-labeled, heat-damaged RBCs is feasible and allowed differentiation of splenic from non-splenic tissues, and the diagnosis of splenic anomalies.