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Contrast Material Injection Can Be Reduced in Elderly Patients

A study conducted by the Department of Technical Radiology at the Nagoya University School of Health Science, Nagoya, Japan, found that the dose of contrast material for elderly patients can be effectively reduced by at least 10% for multidetector CT (MDCT) examinations of the pancreas and biliary regions.

The report, which appeared in the August 2006 edition of the American Journal of Roentgenology,1 assessed 112 patients ranging from 23 to 80 years of age who had known or suspected pancreatobiliary disease, divided into three groups. Group 1 included patients aged 60 or younger whose contrast injection was 0.08 mL/kg/s; Group 2 included patients older than 60 whose contrast injection was 0.08 mL/kg/s; and Group 3 included patients older than 60 with a contrast injection of 0.07 mL/kg/s.

According to the study, “When interpreting CT images acquired using [standard contrast injection] protocol in our clinical practice, we noted that in some examinations of elderly patients, because contrast enhancement of the pancreatic parenchyma in pancreatic phase images was too intense, the standard settings for window width and level used at our institution had to be adjusted to evaluate the parenchyma in detail.”

Contrast enhancement in the aorta, portal venous system, pancreas, and liver was assessed quantitatively. Two radiologists, who were unaware of the patients’ clinical information or the injection protocol used to acquire the CT images, ranked the degree of contrast enhancement on a scale of 1 to 5; the results for different age groups were then statistically compared.

Researchers used a 16-slice Aquilion CT from Toshiba America Medical Systems, Tustin, Calif. Nonionic contrast material with an iodine concentration of 300 mg I/mL was injected at a fixed duration of 30 seconds, and a 5% dextrose flush was injected at a fixed rate of 5 mL/s over 6 seconds immediately following contrast material injection. The injection rate was reduced by 10% for Group 3.

The two radiologists assessed and ranked the images based on specific clinical criteria. For example, in arterial phase scanning, the reviewers assessed whether the images were suitable for delineating the peripancreatic arteries; they also identified images in which arterial enhancement was sufficiently high and in which pancreatic and portal venous assessment was low. In pancreatic phase scanning, the reviewers looked at whether the images were suitable for delineating the pancreatic and bile ducts and detecting pancreatic carcinomas by achieving “intense and homogeneous” enhancement of the pancreatic parenchyma.

Compared with Groups 1 and 2, Group 3 effectively achieved an effective 12.2% reduction in the volume and rate of contrast material injection. In the discussion portion of the report, researchers note that increasing the amount of injected contrast material results in higher costs and a greater risk of complications like renal dysfunction and extravasation, providing dual incentives for administering contrast material at a specific volume and rate.

“In conclusion,” the researchers write in the study, “we recommend reducing the dose and rate of contrast material injection by at least 10% in patients more than 60 years old for multiphase contrast-enhanced CT studies of the pancreatobiliary region with an MDCT scanner. It should be noted that this helps to reduce both the cost of the examination and the risk of complications.”


  1. Itoh S, Ikeda M, Satake H, Ota T, Ishigaki T. The effect of patient age on contrast enhancement during CT of the pancreatobiliary region. AJR Am J Roentgenol. 2006;187:505–510. Available at: Accessed October 20, 2006.