Comparative assessment of CT and sonographic techniques for appendiceal imaging

OBJECTIVE. We performed a comparative assessment of CT and sonographic tech niques 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 appendic eal CT with colonic contrast material, and repeated sonography with colonic contrast material. Each sonogram was videotaped for subsequent interpretat ion by three radiologists and two sonographers. The mean sensitivity, speci ficity, positive and negative predictive values, inter- and intraobserver v ariability, 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 as sessed on a 10-point scale for each radiologic study. Diagnoses were confir med by pathologic evaluation of resected appendixes or clinical follow-up f or a minimum of 3 months after presentation. RESULTS. Twenty-four of the 100 patients had positive findings for acute ap pendicitis. Both sonographic techniques had high specificity (85-89%) and c omparable accuracy (73-75%) but low sensitivity (33-35%) and inter- and int raobserver variability (kappa = 0.15-0.20 and 0.39-0.42, respectively). Une nhanced focused appendiceal CT, abdominopelvic CT, and focused appendiceal CT with colonic contrast material all significantly outperformed sonography (p < 0.0001), with sensitivities of 78%, 72%. and 80%, specificities of 86 %, 91% and 87%, and accuracies of 84%, 87%, and 85%, respectively. Abdomino pelvic CT pave the greatest confidence in cases with negative findings (p = 0.001), and focused appendiceal CT with colonic contrast material gave the greatest confidence for casts with positive findings (p = 0.02). In terms of inter- and intraobserver variability, focused appendiceal CT with coloni c contrast material yielded the highest. and unenhanced focused appendiceal CT the lowest, agreement (interobserver <kappa> = 0.45 vs. 0.36 and intrao bserver kappa = 0.85 vs. 0.76. respectively) (p < 0.05). Colonic contrast m aterial was unsuccessfully advanced into the cecum in 18% of patients and l eaked in another 24%. Patient discomfort was greatest with focused appendic eal CT using colonic contrast material and least with unenhanced focused ap pendiceal CT (p < 0.05). CONCLUSION. A standard abdominopelvic CT scan is recommended as the initial examination for appendicitis in adult patients. However, focused appendice al CT with colonic contrast material material should be used as a problem-s olving technique in difficult cases.