Multiphase acquisitions in pediatric abdominal-pelvic CT are a common practice and contribute to unnecessary radiation dose

Bradley S. Rostad, Kimberly E. Applegate, Tammy Kim, Renee M. Mansour, Sarah S. Milla

Many patients at our pediatric hospital have had a contrast-enhanced CT of the abdomen and pelvis performed by an outside imaging facility before admission. We have noticed that many of these exams are multiphase, which may contribute to unnecessary radiation dose. To determine the frequency of multiphase acquisitions and radiation dose indices in contrast-enhanced CTs of the abdomen and pelvis performed by outside imaging facilities in patients who were subsequently transferred to our pediatric hospital for care, and compare these metrics to contrast-enhanced CTs of the abdomen and pelvis performed internally. A retrospective analysis was performed of contrast-enhanced CTs of the abdomen and pelvis from outside imaging facilities uploaded to our picture archiving and communication system (PACS) between January 1, 2012, and December 31, 2015. CT images and dose pages were reviewed to determine the number of phases and dose indices (CT dose index-volume [CTDIvol], dose-length product, size-specific dose estimate). Exams for abdominal or pelvic mass, trauma or urinary leak indications were excluded. Data were compared to internally acquired contrast-enhanced CTs of the abdomen and pelvis by querying the American College of Radiology (ACR) Dose Index Registry. This review was institutional review board and HIPAA compliant. There were 754 contrast-enhanced CTs of the abdomen and pelvis from 104 outside imaging facilities. Fifty-three percent (399/754) had 2 phases, and 2% (14/754) had 3 or more phases. Of the 939 contrast-enhanced CTs of the abdomen and pelvis performed internally, 12% (115) were multiphase exams. Of 88% (664) contrast-enhanced CTs of the abdomen and pelvis from outside imaging facilities with dose data, CTDIvol was 2.7 times higher than our institution contrast-enhanced CTs of the abdomen and pelvis (939) for all age categories as defined by the ACR Dose Index Registry (mean: 9.4 vs. 3.5 mGy, P<0.0001). The majority (74%) of multiphase exams were performed by 9 of 104 outside imaging facilities. Multiphase acquisitions in routine contrast-enhanced CT of the abdomen and pelvis exams at outside imaging facilities are more frequent than those at a dedicated pediatric institution and contribute to unnecessary radiation dose. A contrast-enhanced CT of the abdomen and pelvis exam from an outside imaging facility with two passes may have as much as four times to six times the dose as the same exam performed with a single pass at a pediatric imaging center. We advocate for imaging facilities with high multiphase rates to eliminate multiple phases from routine contrast-enhanced CT of the abdomen and pelvis exams in children.