Split-bolus MDCT urography technique for evaluating the urinary tract system reduces radiation dose

The split-bolus (cross sectional imaging) MDCT urography technique reduces both radiation dose and number of images produced, according to a recent study conducted by radiologists from Stanford University School of Medicine in Stanford, CA and VA Palo Alto Health Care System in Palo Alto, CA.

“Since CT urography was first conceived, in the late 90s, there have been a multitude of protocols described in the literature. The vast majority of these protocols entail scanning patients before contrast and at multiple phases after the administration of IV contrast,” said Lawrence C. Chow, MD, lead author of the study. “We wanted to show that a similar examination could be achieved with fewer scan acquisitions [meaning potentially less radiation and fewer images] by administering a split-bolus of IV contrast, without sacrificing sensitivity,” he said.

The study consisted of 500 patients with possible urinary tract abnormalities who underwent split-bolus CT urography. CT urography identified 100% of pathologically confirmed renal and ureteral malignancies. Fourteen of 19 confirmed cases of uroepithelial neoplasms involving the bladder were found.

“We believe that the use of CT urography results in a simplified diagnostic evaluation for patients with painless hematuria [presence of blood in the urine] and can potentially replace what previously required two studies: traditional excretory urography plus CT, MR or sonography,” said Dr. Chow.

CT urography had a sensitivity and specificity of 100% and 99%. It also depicted numerous other congenital and abnormalities of the urinary tract.

“We were impressed with the wide spectrum of abnormalities which we were able to see with CT urography and with the ability of CT urography to detect even very small abnormalities such as papillary necrosis, renal tubular ectasia and very small urothelial tumors,” he said.