Comparative Assessment of CT and Sonographic Techniques for Appendiceal Imaging

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Abstract
OBJECTIVE. We performed a comparative assessment of CT and sonographic techniques used to assess appendicitis. MATERIALS AND METHODS. One hundred patients with clinically suspected acute appendicitis were examined with sonography, unenhanced focused appendiceal CT, complete abdominopelvic CT using IV contrast material, focused appendiceal CT with colonic contrast material, and repeated sonography with colonic contrast material. Each sonogram was videotaped for subsequent interpretation by three radiologists and two sonographers. The mean sensitivity, specificity, positive and negative predictive values, inter- and intraobserver variability, and diagnostic confidence scores of all observers were used for comparative performance assessments. The three CT examinations were filmed and interpreted separately by four radiologists. Patient discomfort was assessed on a 10-point scale for each radiologic study. Diagnoses were confirmed by pathologic evaluation of resected appendixes or clinical follow-up for a minimum of 3 months after presentation. RESULTS. Twenty-four of the 100 patients had positive findings for acute appendicitis. Both sonographic techniques had high specificity (85-89%) and comparable accuracy (73-75%) but low sensitivity (33-35%) and inter- and intraobserver variability (κ = 0.15-0.20 and 0.39-0.42, respectively). Unenhanced focused appendiceal CT, abdominopelvic CT, and focused appendiceal CT with colonic contrast material all significantly outperformed sonography (p p = 0.001), and focused appendiceal CT with colonic contrast material gave the greatest confidence for cases with positive findings (p = 0.02). In terms of inter- and intraobserver variability, focused appendiceal CT with colonic contrast material yielded the highest, and unenhanced focused appendiceal CT the lowest, agreement (interobserver κ = 0.45 vs. 0.36 and intraobserver κ = 0.85 vs. 0.76, respectively) (p p <0.05). CONCLUSION. A standard abdominopelvic CT scan is recommended as the initial examination for appendicitis in adult patients. However, focused appendiceal CT with colonic contrast material material should be used as a problem-solving technique in difficult cases.