Nephrotomography.

Abstract

Nephrotomography is a combination of rapid intravenous nephrography and body-section radiography. The procedure has been found to be of considerable value in the differentiation of renal cysts from neoplasms. The technic of the examination has been presented in a preliminary report (1). The only modification in the procedure introduced since the original report is the addition of 5 c.c. of Decholin to the 50 c.c. of Urokon used with each of the two injections. Rapid injection of Decholin in saline is still employed to determine the circulation time prior to the administration of Urokon. We have found that “tagging” the Urokon with Decholin results in a better end-point prior to the first exposure of the examination. Consistently better opacification of the abdominal aorta and its tributaries, especially the renal vasculature, has been obtained by this modification. Results The method to date has been used in 100 cases. Three of the number were normal controls. The remainder of the examinations were done for suspicious findings on intravenous or retrograde pyelography. In 32 cases the kidneys appeared normal. There was 1 inconclusive examination in this group and 2 must be considered misdiagnoses. In both of these instances there was noted relative opacification in the region of the renal pelvis. Neoplasm was questioned, but surgery revealed normal kidneys. Cysts were demonstrated in 42 cases. Of these, 10 showed bilateral cyst formation. In 3 cases cysts were suspected on one side only on routine urography, but nephrotomography revealed their occurrence in the opposite kidney as well. The other 7 cases were felt to be polycystic kidneys, a diagnosis substantiated by this method (Fig. 1). The remaining 32 cysts were solitary or were demonstrated in only one kidney. In 26 cases the diagnosis of cyst was subsequently proved, in 23 by surgery and in 3 by aspiration. Seven have not been proved but the nephrotomograms were felt to be of sufficient diagnostic significance to warrant careful follow-up without resort to surgery or aspiration (Figs. 2-5). In 1 case (Fig. 6) routine urographic studies were strongly suggestive of neoplasm rather than a cyst, but nephrotomography disclosed a large, well defined cyst, which was later proved surgically. Six of the examinations of cysts were termed inconclusive; 4 because of poor quality and 2 because the cyst arose from the surface of the kidney and did not present the usual well defined radiolucent defect in the opacified renal parenchyma. The diagnosis of “probable cyst” was made in all these cases and was surgically substantiated. Eleven carcinomas of the kidney were diagnosed by nephrotomography (Figs. 7 and 8). In 5 of these cases an abnormal renal vascular bed was demonstrated.