Split vs. Single Bolus CT Urography: Comparison of Scan Time, Image Quality and Radiation Dose

Nicole Morrison,Sherrie Bryden,Andreu F Costa

doi:10.3390/tomography7020019

Nicole Morrison, Sherrie Bryden + Show 1 more

Open Access

https://doi.org/10.3390/tomography7020019

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Abstract

The purpose of this study was to compare the scan time, image quality and radiation dose of CT urograms (CTU) using a split vs. single bolus contrast media injection technique. A total of 241 consecutive CTUs performed between August 2019-February 2020 were retrospectively reviewed. There were three study groups: Group 1, <50 years old, 50/80 cc split-bolus administered at 0 and 700 s post initiation of injection, with combined nephrographic and excretory phases; group 2, ≥50 years old, same split-bolus protocol; and group 3, ≥50 years old, 130 cc single bolus injection, with nephrographic and excretory phases acquired at 100 s and 460 s post injection initiation. The recorded data elements were scan time, number of excretory phases, imaging quality based on opacification of the urinary collecting system (<50%, 50–75%, 75–100%), and dose-length product (DLP). Associations between group and categorical variables were assessed (Chi-square); mean scan time and DLP were compared (one-way ANOVA). Following analysis, proportionally fewer CTUs required a repeat excretory phase in group 3 (32/112, 28.6%) than in groups 1 (25/48, 52.1%) and 2 (37/80, 46.3%) (p = 0.006). Mean scan time was significantly lower in group 3 (678 s) than in groups 1 (1046 s) and 2 (978 s) (p < 0.0001). There was no association between groups and image quality (p = 0.13). DLP was higher in group 3 (1422 ± 837 mGy·cm) than in groups 1 (1041 ± 531 mGy·cm) and 2 (1137 ± 646 mGy·cm) (p = 0.003). In conclusion, single bolus CTU resulted in significantly fewer repeat phases and faster scan time at the expense of a slightly higher radiation dose.

Highlights

IntroductionCT urography (CTU) is a valuable imaging examination for assessing a variety of conditions
The American Urological Association (AUA) recommends CT urography (CTU) in patients with asymptomatic microhematuria that persists after treatment or exclusion of any benign causes [2], and these guidelines have been endorsed by the American College of Physicians [3]
One CTU was excluded from the scan time and imaging quality assessment as the patient became anxious during examination, and the CT

Summary

Introduction

CT urography (CTU) is a valuable imaging examination for assessing a variety of conditions. The 2019 American College of Radiology (ACR) Appropriateness Criteria rate CTU as the first-line imaging examination for patients with microhematuria and risk factors for urologic malignancy, and no history to suggest a benign cause [1]. The American Urological Association (AUA) recommends CTU in patients with asymptomatic microhematuria that persists after treatment or exclusion of any benign causes [2], and these guidelines have been endorsed by the American College of Physicians [3]. Additional indications for CTU include evaluation of patients with gross hematuria, for which the pre-test probability of malignancy is 30–40% [1], staging and surveillance of patients with urinary tract malignancy, assessing for urinary tract injury or postsurgical integrity, congenital abnormalities, and urinary obstruction [4,5]

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