American College of Radiology

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October 16, 2017

Don’t use a protocol for abdominal CT that includes unenhanced CT followed by IV contrast-enhanced CT, except for the following indications: renal lesion characterization, hematuria work up, indeterminate adrenal nodule characterization, follow-up after endovascular stent repair, gastrointestinal hemorrhage or characterizing a focal liver mass.

With the goal of modulating patient radiation exposure and costs, IV contrast enhanced multidetector CT (MDCT) protocols should include an unenhanced acquisition only if it will provide additional diagnostic information. In conjunction with IV contrast enhanced abdominal MDCT, the literature supports an unenhanced acquisition for the following indications:
(1) Renal lesion characterization or hematuria work up
a. Compare unenhanced with post-contrast to identify enhancement in a mass
(2) Adrenal nodule characterization
a. IV contrast phases are not necessary if nodule measures <10 Hounsfield units (HU) on unenhanced CT.
b. If ≥ 10 HU, unenhanced attenuation is used to calculate percentage washout.
(3) Endovascular stent evaluation
a. Unenhanced scan enables distinction of calcification from endoleak when compared to post-contrast images
(4) Gastrointestinal bleeding
a. Unenhanced CT enables definitive distinction of intraluminal hemorrhage from other high-density material (i.e., medication, fecal matter); however,
protocols that use only arterial and venous phase acquisitions may be sufficient, as hemorrhage changes configuration between the 2 phases.
b. If available, dual energy can be used to create a virtual unenhanced dataset and avoid the unenhanced acquisition.
(5) Focal liver mass
a. Compare unenhanced with post contrast to identify enhancement in a mass

These items are provided solely for informational purposes and are not intended as a substitute for consultation with a medical professional. Patients with any specific questions about the items on this list or their individual situation should consult their physician.

How The List Was Created

(1-5) The American College of Radiology (ACR) initially solicited expert opinion from physician leaders with its Board of Chancellors. A working group was then formed to further identify common clinical scenarios in which imaging may be misused and should be reconsidered. Members of the group included the physician chairs or vice chairs of seven ACR commissions such as Quality and Safety, Appropriateness Criteria and Metrics. An initial list of topics was narrowed down based on the highest potential for improvement, representing a broad range of tests and the availability of strong guidelines. Members then researched specific recommendations and evidentiary statements based on their expertise. Recommendations that were too general or were well covered by other existing measures and initiatives were eliminated to identify the final five things list.

(6-10) The Choosing Wisely initiative was presented to the organization’s physician leaders at a Board of Chancellors meeting and a working group selected five initial low-value imaging targets for reduced utilization. The second set of targets was created by the following working group, with the goals of minimizing unnecessary imaging and biopsy generated by discovery of incidental findings, improving patient safety through reduced radiation exposure, and reducing unnecessary consultations based on imaging findings.

  • Pamela T. Johnson, MD, Chair, Choosing Wisely Recommendations
  • Jacqueline A. Bello, MD, FACR, Chair of Commission on Quality and Safety
  • Mythreyi B. Chatfield, PhD, Executive Vice President for Quality and Safety
  • Jonathan Flug, MD, MBA, Quality Management Committee
  • Jenny K. Hoang, MBBS, lead author on ACR White Paper for Managing Incidental Thyroid Nodules
  • Alec J. Megibow, MD, MPH, FACR, Committee on Economics – Body Imaging Commission
  • Pari V. Pandharipande, MD, MPH, Chair of Committee on Incidental Findings
  • Saurabh Rohatgi, MD, Committee on Quality Experience – Commission on Patient and Family Centered Care

Research: For the topics related to incidental findings on imaging exams, the American College of Radiology has created evidence-based white papers to provide guidance to practicing radiologists on making management recommendations. The white paper publications and additional relevant literature serve as the evidence supporting those recommendations. For the remaining recommendations pertaining to body CT protocol design, published literature was reviewed to define acceptable indications for multiphase protocols.

ACR’s disclosure and conflict of interest policy can be found at


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