Helical CT technique for the diagnosis of appendicitis: prospective evaluation of a focused appendix CT examination.

PURPOSE: To evaluate a focused, helical computed tomographic (CT) technique for imaging the appendix in patients suspected of having appendicitis.

MATERIALS AND METHODS: One hundred patients prospectively underwent appendix CT examination, with use of oral and colon contrast media and contiguous, thin-collimation, helical CT imaging of the right lower quadrant. Results were correlated with the results of surgery and pathologic examination from 61 patients or from clinical follow-up in 39 patients.

RESULTS: CT scans were positive for appendicitis in 59 patients: true-positive in 56 patients on the basis of surgery and pathologic examination, and false-positive in two patients on the basis of clinical follow-up; in the case of the other positive scan, the clinical outcome was indeterminate. CT scans were negative for appendicitis in 41 patients: true-negative in five patients on the basis of surgery and pathologic examination, and true-negative in 36 patients on the basis of clinical follow-up. CT had a sensitivity of 100%, a specificity of 95%, a positive predictive value of 97%, a negative predictive value of 100%, and an accuracy of 98%. The normal appendix was always identified. CT helped establish alternative diagnoses in 33 of the 41 patients (80%) in whom the results of CT were negative for appendicitis.

CONCLUSION: Appendix CT examination can help diagnose or exclude appendicitis and establish an alternative diagnosis.