RESUMEN
Because adenocarcinoma of the breast expresses receptors for alpha-fetoprotein (AFP), we studied Tc-99m AFP as a radiopharmaceutical to detect breast cancer. The biodistribution of Tc-99m radiolabeled natural human AFP (full length) and recombinant domain III (DIII) of human AFP was compared to Tc-99m sestamibi and Tl-201 in a murine model of human breast cancer. Estrogen receptor positive (MCF7, T-47D) and estrogen receptor negative (MDA-MB-231, BT-20) human breast cancer xenografts were grown subcutaneously in the lateral thorax region of immunosuppressed mice (ICR SCID). Quantitative comparisons of percent-injected dose per gram of tissue (%ID/gram) and tumor to thigh ratio (T/Th) were performed at 0-60 minutes and at 24 hours following injection. For most tumors, T/Th for AFP and DIII was significantly greater than T/Th for Tc-99m sestamibi and Tl-201. In all breast cancers (BT-20, MCF7, MDA-MB-231, T-47D), Tc-99m AFP T/Th increased from 60 minutes to 24 hours, suggesting good tumor retention of this radiopharmaceutical. DIII and AFP had significantly higher %ID/gram than either Tl-201 or Tc-99m sestamibi when considered across all tumor types at both 60 minutes and 24 hours. The data suggests that localization of Tc-99m AFP in human breast cancer xenografts is initially rapid, increases with time, and is superior to Tc-99m sestamibi and Tl-201. Given its high uptake by breast cancer cells, its low non-tumor localization and its rapid renal excretion, these Tc-99m AFP preparations may be useful agents to detect human breast carcinoma.
Asunto(s)
Neoplasias de la Mama/diagnóstico por imagen , Radiofármacos , Tecnecio , alfa-Fetoproteínas , Animales , Carcinoma Hepatocelular , Femenino , Humanos , Ratones , Ratones Endogámicos ICR , Ratones SCID , Cintigrafía , Radiofármacos/farmacocinética , Receptores de Estrógenos/análisis , Proteínas Recombinantes/farmacocinética , Tecnecio/farmacocinética , Tecnecio Tc 99m Sestamibi/farmacocinética , Radioisótopos de Talio , Distribución Tisular , Trasplante Heterólogo , Células Tumorales Cultivadas , alfa-Fetoproteínas/farmacocinéticaRESUMEN
A patient with shortness of breath had a high probability lung scan for pulmonary embolism, but no obvious embolic source. Whole-body scintigraphy using Tc-99m labeled Fab' antifibrin monoclonal antibody showed large central pulmonary emboli as well as tracer uptake in the right atrium and aortic arch. No lower extremity clot was detected. This case shows significant differences in the appearance of pulmonary embolism as assessed by direct clot and ventilation-perfusion scintigraphy. It shows the importance of the heart as the origin of pulmonary emboli and the utility of direct thrombus visualization.