Abstract
Background
Appendiceal diameter continues to be cited as an important criterion for diagnosis of appendicitis by computed tomography (CT).
Objective
To assess sources of error and variability in appendiceal diameter measurements by CT.
Materials and methods
In this institutional review board-approved review of imaging and medical records, we reviewed CTs performed in children <18 years of age between Jan. 1 and Dec. 31, 2010. Appendiceal diameter was measured in the axial and coronal planes by two reviewers (R1, R2). One year later, 10% of cases were remeasured. For patients who had multiple CTs, serial measurements were made to assess within patient variability. Measurement differences between planes, within and between reviewers, within patients and between CT and pathological measurements were assessed using correlation coefficients and paired t-tests.
Results
Six hundred thirty-one CTs performed in 519 patients (mean age: 10.9 ± 4.9 years, 50.8% female) were reviewed. Axial and coronal measurements were strongly correlated (r = 0.92-0.94, P < 0.0001) with coronal plane measurements significantly larger (P < 0.0001). Measurements were strongly correlated between reviewers (r = 0.89-0.9, P < 0.0001) but differed significantly in both planes (axial: +0.2 mm, P=0.003; coronal: +0.1 mm, P=0.007). Repeat measurements were significantly different for one reviewer only in the axial plane (0.3 mm difference, P<0.05). Within patients imaged multiple times, measured appendix diameters differed significantly in the axial plane for both reviewers (R1: 0.5 mm, P = 0.031; R2: 0.7 mm, P = 0.022).
Conclusion
Multiple potential sources of measurement error raise concern about the use of rigid diameter cutoffs for the diagnosis of acute appendicitis by CT.
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Acknowledgments
Dr. Trout discloses the following: grant support from Siemens Healthcare, and advisory board and travel support from Philips Healthcare. Dr. Towbin discloses the following: grant support from Siemens Healthcare, consultant for Guerbet and Applied Radiology, and shareholdings with Merge Healthcare. Dr. Zhang has no disclosures.
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Trout, A.T., Zhang, B. & Towbin, A.J. Measurement error in CT assessment of appendix diameter. Pediatr Radiol 46, 1831–1836 (2016). https://doi.org/10.1007/s00247-016-3699-3
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DOI: https://doi.org/10.1007/s00247-016-3699-3