Bioelectric impedance analysis helps identify when contrast material is necessary before abdominopelvic CT

Calculating a patient’s body fat percentage and body mass index (BMI) can help imaging providers determine whether or not to use oral contrast material before abdominopelvic CT exams, according to a new study published in the American Journal of Roentgenology.

The authors studied data from 101 patients who presented to a level 1 trauma center’s emergency department (ED) from June 1 to July 19, 2016. The BMI and body fat percentage were determined for each patient, with body fat percentages being calculated using a handheld bioelectric impedance analysis (BIA) device. Three radiologists, blinded to the collected data, then looked at the amount of intraabdominal and intrapelvic fat seen on each patient’s CT images and assigned them a score from 1 to 5.

Overall, 97 percent of the patients with a high BMI had “sufficient amounts” of intraabdominal and intrapelvic fat that allow delineation of anatomic structures without using oral contrast material. Eighty-three percent of patients with a low BMI did not have enough fat to allow such delineation. When a patient’s BMI is intermediate, a body fat percentage of 30 percent or more can help determine if oral contrast material is necessary or not.

“Our results show that using BMI with the addition of BIA-determined body fat percentage in appropriate cases provides a rapid and refined approach for estimating the amount of intraabdominal and intrapelvic fat in patients presenting to the ED with nontraumatic abdominal pain,” wrote author Patrick McLaughlin, MD, department of emergency and trauma radiology at Vancouver General Hospital, and colleagues. “Using these criteria may help optimize use of oral contrast material, which would improve workflow and reduce wait times in the ED.”