RESUMO
A radiolabelled monoclonal antibody (NDOG2) directed against placental alkaline phosphatase (PLAP) was used in the radio-immunodetection of ovarian carcinoma. Tumour deposits were successfully visualized in 11 of 15 patients and the abnormalities demonstrated were classified as focal or diffuse. Of the 11 patients, eight showed focal abnormalities alone and three had a diffuse abnormality, of which two also showed a focal abnormality. False-positive results may occur not only due to uptake of 123I by gut mucosa and an inadequately blocked thyroid gland but also from activity in an incompletely emptied bladder. A false-negative result occurred due to high background activity in the liver masking a known, discrete tumour deposit.
Assuntos
Fosfatase Alcalina/imunologia , Anticorpos Monoclonais , Neoplasias Ovarianas/diagnóstico por imagem , Placenta/enzimologia , Ceco/diagnóstico por imagem , Reações Falso-Negativas , Reações Falso-Positivas , Feminino , Humanos , Estadiamento de Neoplasias , Neoplasias Ovarianas/enzimologia , CintilografiaRESUMO
The biodistribution of a radiolabelled monoclonal antibody (123I-NDOG2) was studied in patients with ovarian tumour. It was found that the uptake patterns in known tumour sites was variable and that the clearance of the agent from the vascular pool was due to renal excretion of the radionuclide and the redistribution of the radioactively labelled compound into other compartments. The mean (+/- SD) plasma clearance time was 20.8 (+/- 2.3) h and the ratios of target (tumour) to background (thigh) ranged between 1.4 and 4.8. The ratio between the plasma radioactivity at either 3.5 or 20 h after administration was calculated relative to the initial plasma radioactivity. These values (0.79 and 0.48, respectively) were incorporated into an image-subtraction technique that allowed for redistribution outside the vascular pool. A whole-body dose equivalent to 16.3 mu Sv MBq-1 (60.4 mrem.mCi-1) was calculated.
