Collateral pathways in superior vena caval obstruction as seen on gamma images.

The collateral pathways, known from contrast studies to take over the drainage of blood from the various parts of the body when the superior vena cava or its major tributaries are occluded because of disease, can easily be demonstrated with equal clarity (except for the vertebral plexus pathway) by radionuclides. The failure to delineate the vertebral plexus pathway is felt to lie in the close anatomical relationship between the vertebral plexus and the vertebrae, which cause attenuation of the emerging photons. Because of the existing anastomotic channels and their anatomical direction, location and distribution of the individual collateral pathways are individually identifiable. The site/level, extent, degree, and probable duration of occlusion directly affect the degree and extent of the collaterals that subsequently develop. In 20 of 49 abnormal radionuclide superior venacavograms, incidental but abnormal imaging features not ascribable to caval obstruction or syndrome were noted. These included persistent left superior vena cava, aortic aneurysm, pericardial effusion, and disparity in pulmonary perfusion.

Scintigraphic features of superior vena cava obstruction due to substernal non-toxic goitre.

Four men with clinical features of superior vena caval syndrome due to large substernal non-toxic multinodular goitre have undergone radionuclide superior vena caval studies. In all cases the dynamic scintigraphs showed a characteristic thyroidal configuration attributed to the definition of stretched thyroidal veins and their tributaries. Radiocontrast studies of two patients demonstrated the characteristic thyroid configuration. A radionuclide superior venacavogram taken post-thyroid lobectomy in one case showed the features had reverted to normal.

[99mTc] pertechnetate radionuclide venography--large-volume injection without tourniquet.

Radionuclide venography was performed in patients who were suspected clinically to have thromboembolic disease of the lower extremities and/or pelvis. A moderately large volume of pertechnetate was administered in the dorsal vein of each foot without the benefit of applied tourniquets at the time of injection. Sixty-five (27.2%) of 242 studies were abnormal; the majority revealed defect(s) and collaterals, some collaterals only, and a few defects only. In 140 normal patients only the deep venous system was outlined in 74.5%, while the remainder defined one or both sides of the superficial venous system (great saphenous vein). The merits and apparent advantages derived from radionuclide venographic procedure are discussed. The method is simple, reproducible, and useful in assessing thromboembolic disease, particularly in the deep venous system of the lower extremities and pelvis.

Occlusion of inferior vena cava--features by radionuclide venography.

Six adults with inferior vena caval obstruction are presented. Three were the results of surgical intervention, two were secondary to large thrombi, and one was due to pressure from a large renal-cell carcinoma and adjacent nodes. All underwent a modified approach of radionuclide venography, using a moderately large volume of sodium pertechnetate. Features characteristic of inferior vena caval obstruction were demonstrated in five of the six patients, and these various features are described and discussed.

Unusual bone images in hyperparathyroidism.

Whole-body scans with 99Tcm-Sn polyphosphate were performed on four patients suffering from hyperparathyroidism. Two of the patients were investigated twice, at intervals of five and eight months. A variety of unusual but symmetrical images were obtained, not always confined to the skeleton. It is suggested that in conditions of renal failure the radiopharmaceutical may be avidly accumulated on first passage by calcifying areas in the soft tissues. Deteriorating blood supply to the bones reduces uptake of 99Tcm in the the skeleton.