Distinguishing Lipid-Poor Adrenal Adenoma from Non-Adenomatous Lesions: Accuracy of Identification and the Most Appropriate Contrast Washout Index Using the Contrast-Enhanced Washout Multidetector CT 10-Minute Delayed Imaging Protocol

Authors

  • Parames Seevaleephan Department of Radiology, Faculty of Medicine, Siriraj Hospital, Mahidol University
  • Nithida Na Songkhla Department of Radiology, Faculty of Medicine, Siriraj Hospital, Mahidol University

Keywords:

10-minute contrast washout CT, Adrenal adenoma, Absolute percentage washout, Lipid poor adenoma, Relative percentage washout

Abstract

Background: Because of the contrast washout characteristic of adrenal adenoma, Siriraj Hospital uses the 10-minute delayed imaging computed tomography (CT) protocol to evaluate adrenal masses. No reports in Thailand have described the performance of this protocol to date.

Objective: This study was performed to identify the accuracy of identification and the most appropriate contrast washout index to distinguish lipid-poor adrenal adenoma from non-adenomatous lesions using the 10-minute delayed imaging CT protocol.

Materials and Methods: This retrospective review involved patients who underwent the CT adrenal protocol with 10-minute delayed imaging at Siriraj Hospital from January 2005 to December 2017. In total, 285 adrenal masses that were smaller than 4 cm and had a poor lipid component (density of >10 HU) were assessed in 261 patients who were given a pathologic diagnosis or underwent follow-up imaging. Non-contrast images were obtained before intravenous contrast administration with an 80-second and 10-minute scan delay. The absolute percentage washout (APW) and relative percentage washout (RPW) of the adrenal masses were calculated. Receiver operating characteristic analysis was performed to evaluate the protocol performance and the most appropriate contrast washout value with which to identify lipid-poor adrenal adenoma.

Results: The test appeared to be the most accurate when using an APW of 47% and RPW of 34%. The APW of 47% showed a sensitivity of 96.5%, specificity of 89.3%, and accuracy of 95.8% (p < 0.001), while the RPW of 34% showed a sensitivity of 89.5%, specificity of 96.4%, and accuracy of 90.2% (p < 0.001).

Conclusion: An APW of 47% and RPW of 34% were the most appropriate washout indexes, offering high accuracy to distinguish lipid-poor adrenal adenoma from non-adenomatous lesions.

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References

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ROC curve of RPW

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Published

2022-07-11

How to Cite

1.
Seevaleephan P, Na Songkhla N. Distinguishing Lipid-Poor Adrenal Adenoma from Non-Adenomatous Lesions: Accuracy of Identification and the Most Appropriate Contrast Washout Index Using the Contrast-Enhanced Washout Multidetector CT 10-Minute Delayed Imaging Protocol. J Chulabhorn Royal Acad [Internet]. 2022 Jul. 11 [cited 2022 Oct. 3];4(3):95-102. Available from: https://he02.tci-thaijo.org/index.php/jcra/article/view/253958

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Research Articles