Color Doppler Imaging of the Appendix

Criteria to Improve Specificity for Appendicitis in the Borderline-Size Appendix

Authors

  • Xu Yingding MD,

    1. Department of Radiology, Stanford University School of Medicine, Stanford, California USA
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  • Jeffrey R. Brooke MD,

    1. Department of Radiology, Stanford University School of Medicine, Stanford, California USA
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  • Shin Lewis K. MD,

    1. Department of Radiology, Stanford University School of Medicine, Stanford, California USA
    2. Department of Radiology, Stanford University School of Medicine, Stanford, California USA, Department of Radiology, Veterans Affairs Palo Alto Health Care System, Palo Alto, California USA
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  • DiMaio Michael A. MD,

    1. Department of Radiology and Pathology, Stanford University School of Medicine, Stanford, California USA
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  • Olcott Eric W. MD

    Corresponding author
    1. Department of Radiology, Stanford University School of Medicine, Stanford, California USA
    2. Department of Radiology, Stanford University School of Medicine, Stanford, California USA, Department of Radiology, Veterans Affairs Palo Alto Health Care System, Palo Alto, California USA
    • Address correspondence to Eric W. Olcott, MD, Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, H1307, Stanford, CA 94305-5105 USA.

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Abstract

Objectives

To test the hypothesis that continuous intramural vascular signal measuring at least 3 mm on color Doppler imaging is highly specific for appendicitis in patients with diagnostically borderline-size appendices.

Methods

Two blinded observers independently reviewed color Doppler images of the appendix in 94 consecutive patients who had undergone sonography for suspected appendicitis and whose appendices were of diagnostically borderline size (6–8 mm maximum outer diameter). Intramural vascular flow on color Doppler images was classified as absent, type 1 (only punctate and dispersed signal), or type 2 (continuous linear or curvilinear signal measuring at least 3.0 mm in long- or short-axis views). Histopathologic examination and clinical follow-up served as reference standards. Proportions were assessed by the exact binomial test.

Results

Of the 94 patients, 33 (35.1%) had type 1 flow (of whom 5 [15.2%] had appendicitis); 23 (24.5%) had type 2 flow (of whom 20 [87.0%] had appendicitis); and 38 (40.4%) had absent flow (of whom 10 [26.3%] had appendicitis). The sensitivity, specificity, and odds ratio of type 2 flow as an indicator of appendicitis were 57.1%, 94.9%, and 24.9 (P< .001), respectively; the corresponding values for type 1 flow as an indicator of normal appendices were and 47.5%, 85.7%, and 5.4 (P = .002).

Conclusions

Continuous intramural linear or curvilinear signal measuring at least 3 mm on color Doppler imaging is a highly specific, although relatively insensitive, sign of acute appendicitis in noncompressible appendices of diagnostically borderline size (6–8 mm).

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