Radionuclide diagnosis of paediatric retroperitoneal tumours using 99mTc-pyrphotech

Abstract

Forty-five children with retroperitoneal lesions were studied using 99mTc-pyrphotech (a complex of 99mTc with pyrophosphate) by dynamic and static scintigraphy. Highest efficacy in the visualisation of primary neuroblastomas and Wilms' tumours (WT) (86.7% and 91.7%, respectively) was recorded in early static scintigraphy (a series of scintigraphies after 20–30 min of investigation). Scintigrams obtained within 20–30 min of dynamic scintigraphy and later static scintigraphy, i.e. 2–3 h after administration of 99mTc-pyrphotech, revealed lower efficacy (73.3% and 58.3%; 73.3% and 50%, respectively). Sufficiently accurate information on the anatomotopographic kidney status was obtained during scintigram evaluation within the initial 5 min of investigation. Scintigrams showing, at this time, a non visible kidney or defective drug incorporation in the renal parenchyma and the respective visualised tumours at later scintigraphy were typical of WT, while the absence of such defects, together with tumour visualisation, were characteristic of neuroblastoma. Considering the above scintigraphic patterns and optimal time intervals in the study of the kidney and tumour, the sensitivity of radionuclide diagnosis of neuroblastoma and WT was 86.7% and 91.7%, respectively, the specificity being 100%. In malignant lymphomas, patients with retroperitoneal node lesions showed the drug hyperfixation in the projection of the ureter compressed by the tumour masses, while in patients with the process of leukaemisation, the drug was predominantly incorporated in the central compartments of the renal segments; renograms were characteristic of the diffuse type lesion. Evaluation of renograms obtained during dynamic scintigraphy with 99mTc-pyrphotech, enabled detection of renal dysfunction in the majority of patients. Osteoscintigraphy during the conclusive stage of investigations revealed skeletal lesion foci.