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HYPAQUE sodium 50 percent is indicated for excretory urography, cerebral and peripheral angiography, aortography, intraosseous venography, direct cholangiography, hysterosalpingography, splenoportography, and contrast enhancement of computed tomographic head imaging. Diatrizoate salts are used in small, medium, and large dose urography (see Dosage and Administration—EXCRETORY UROGRAPHY). Visualization of the urinary tract can be achieved by either direct intravenous bolus injection, intravenous drip infusion, or incidentally following intra-arterial procedures.Visualization of the urinary tract is delayed in infants less than 1 month old, and in patients with urinary tract obstruction (see CLINICAL PHARMACOLOGY). Injectable radiopaque contrast media may be used to refine diagnostic precision in areas of the brain which may not otherwise have been satisfactorily visualized. Radiopaque diagnostic agents may be useful to investigate the presence and extent of certain malignancies such as: gliomas including malignant gliomas, glioblastomas, astrocytomas, oligodendrogliomas and gangliomas, ependymomas, medulloblastomas, meningiomas, neuromas, pinealomas, pituitary adenomas, craniopharyngiomas, germinomas, and metastatic lesions. The usefulness of contrast enhancement for the investigation of the retrobulbar space and in cases of low grade or infiltrative glioma has not been demonstrated. In calcified lesions, there is less likelihood of enhancement. Following therapy, tumors may show decreased or no enhancement. The opacification of the inferior vermis following contrast media administration has resulted in false-positive diagnosis in a number of normal studies. The use of injectable radiopaque diagnostic agents may be beneficial in the image enhancement of nonneoplastic lesions. Cerebral infarctions of recent onset may be better visualized with contrast enhancement, while some infarctions are obscured if contrast media are used. The use of iodinated contrast media results in contrast enhancement in about 60 percent of cerebral infarctions studied from one to four weeks from the onset of symptoms. Sites of active infection may also be enhanced following contrast media administration. Arteriovenous malformations and aneurysms will show contrast enhancement. For these vascular lesions, the enhancement is probably dependent on the iodine content of the circulating blood pool. Hematomas and intraparenchymal bleeders seldom demonstrate any contrast enhancement. However, in cases of intraparenchymal clot, for which there is no obvious clinical explanation, contrast media administration may be helpful in ruling out the possibility of associated arteriovenous malformation. Diatrizoate salts are used for radiographic studies throughout the cardiovascular system. Intravascular radiopaque diagnostic agents of high concentration are not recommended for cerebral or spinal angiography (see CONTRAINDICATIONS—General), and contrast agents with the lowest compatible viscosity and higher concentration of iodine (310 mg/mL to 480 mg/mL of bound iodine) must be used for angiocardiography. Contrast media approaching serum ionic content and osmolality have less potential for deleterious effects on the myocardium (see PRECAUTIONS—General, Drug Interactions). Addition of chelating agents may contribute to toxicity in coronary angiography, and the sodium content of angiographic agents used in coronary arteriography is of crucial importance. In addition to the following general CONTRAINDICATIONS, WARNINGS, PRECAUTIONS, and ADVERSE REACTIONS, there are additional listings in these categories under the particular procedures.