Nephrography; simplified technic.

Abstract

Although the kidneys are opaque to roentgen rays, their density is that of soft tissues in general and their roentgen image is difficult to distinguish from surrounding structures. Perirenal fat deposits are relatively radiolucent, thereby allowing limited examination of the renal outline by means of routine roentgenography. Even under favorable circumstances, however, the upper pole of one or both kidneys is occasionally indistinguishable. Artificial methods of increasing the density and contrast are called nephrography. The following have been developed and found to be effective. A. Abdominal Aortography: dos Santos (1), and later Nelson (2), obtained increased renal opacity by direct translumbar injection of radiopaque medium into the abdominal aorta. Nelson was able to demonstrate bilateral hypernephromata when both intravenous and retrograde pyelography had failed. Abdominal aortography was used by Wagner (3) to delineate the arterial supply of a large renal tumor. This method necessitates the use of general anesthesia and has in one case been followed by death due to mesenteric arterial thrombosis (4). B. Intravenous Pyelography with Ureteral Obstruction: When acute ureteral obstruction is present, the renal shadow is rendered more than usually radiopaque during intravenous pyelography. Hellmer (5), while studying this phenomenon, was able to recognize a renal cyst and a tumor as radiolucent areas in the opacified kidney. Obstruction of the ureter was artificially produced by Weens and Florence (6) by the dilatation of a balloon which had been introduced into the ureter, a procedure allowing them to obtain roentgenograms of the opacified kidney. C. Rapid Intravenous Injection of Concentrated Organic Iodide Solutions: An abstract by Weens et al. (7) described the use of intravenous diodrast to produce nephrograms, but their results were not illustrated. The method of injection developed by Robb and Steinberg for contrast cardiovascular visualization was employed (8). The method to be described here is essentially the same. Material and Method The preparation for nephrography is the same as that preceding routine intravenous pyelography. The evening before the examination, the patient receives one ounce of castor oil. If this is effective, no further preparation is necessary; if not, a tap water enema is administered the following morning. Fluids are restricted after midnight and breakfast is omitted. At the time of nephrography, the patient is placed in the supine position on the roentgenographic table, and a preliminary film of the abdomen is made to ascertain the proper exposure factors and the adequacy of preparation. The usual roentgenographic factors are: 200 ma., 75 to 90 kv.p. (varying with the thickness of the patient), Potter-Bucky diaphragm, 40-inch target-film distance, and 0.3 second exposure.