American College of Radiology

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October 16, 2017

Don’t routinely use a protocol for abdominal CT that includes a delayed post-contrast phase after the venous phase, except for the following indications: renal lesion characterization, hematuria work up, CT urogram, indeterminate adrenal nodule characterization, hepatocellular carcinoma and cholangiocarcinoma.

With the goal of modulating patient radiation exposure, IV contrast enhanced multidetector CT (MDCT) protocols should include a delayed post contrast acquisition (defined as an acquisition after the portal venous, hepatic or nephrographic phases) only if it will provide additional diagnostic information.

The literature supports an additional delayed acquisition for the following indications:
(1) Renal lesion characterization, hematuria work up or CT urogram
a. contrast enhancement pattern of solid renal mass over time provides diagnostic information about pathologic subtype
b. delayed phase defines relationship of solid renal mass relationship to collecting system
c. delayed phase facilitates identification of transitional cell carcinoma and traumatic injury
(2) Adrenal nodule characterization
a. delayed attenuation used to calculate Absolute Percentage Washout and Relative Percentage Washout
(3) Hepatocellular carcinoma
a. multiple acquisitions facilitate lesion detection and washout characterization
(4) Cholangiocarcinoma
a. enhancement increases over time, justifying use of delayed in patients where distinction between cholangiocarcinoma and HCC is required.

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


Chan MG, Cassidy FH, Andre MP, Chu P, Aganovic L. Delayed imaging in routine CT examinations of the abdomen and pelvis: is it worth the additional cost of radiation and time? AJR Am J Roentgenol. 2014 Feb;202(2):329-35. doi: 10.2214/AJR.12.10468. PubMed PMID: 24450673.

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Iannaccone R, Laghi A, Catalano C, Rossi P, Mangiapane F, Murakami T, Hori M, Piacentini F, Nofroni I, Passariello R. Hepatocellular carcinoma: role of unenhanced and delayed phase multi-detector row helical CT in patients with cirrhosis. Radiology. 2005 Feb;234(2):460-7. PubMed PMID: 15671002.

Lim JH, Choi D, Kim SH, Lee SJ, Lee WJ, Lim HK, Kim S. Detection of hepatocellular carcinoma: value of adding delayed phase imaging to dual-phase helical CT. AJR Am J Roentgenol. 2002 Jul;179(1):67-73. PubMed PMID: 12076907.

Keogan MT, Seabourn JT, Paulson EK, McDermott VG, Delong DM, Nelson RC. Contrast-enhanced CT of intrahepatic and hilar cholangiocarcinoma: delay time for optimal imaging. AJR Am J Roentgenol 1997;169:1493-9.

Loyer EM, Chin H, DuBrow RA, David CL, Eftekhari F, Charnsangavej C. Hepatocellular carcinoma and intrahepatic peripheral cholangiocarcinoma: enhancement patterns with quadruple phase helical CT a comparative study. Radiology 1999;212:866-75.