1802 AJR:184, June 2005 AJR 2005;184:1802–1808 0361–803X/05/1846–1802 © American Roentgen Ray Society Rhea et al. Appendiceal CT in an Urban Medical Center The Status of Appendiceal CT in an Urban Medical Center 5 Years After Its Introduction: Experience with 753 Patients James T. Rhea 1,2 Elkan F. Halpern 1 Thomas Ptak 1 James N. Lawrason 1 Richard Sacknoff 1 Robert A. Novelline 1 Rhea JT, Halpern EF, Ptak T, Lawrason JN, Sacknoff R, Novelline RA Received June 2, 2004; accepted after revision September 25, 2004. 1 Harvard Medical School and Department of Radiology, Massachusetts General Hospital, Boston, MA 02114. 2 Present address: Department of Radiology, San Francisco General Hospital, 1001 Potrero Ave., Rm. 1x55, San Francisco, CA 94110. Address correspondence to J. T. Rhea (jrhea@sfghrad.uscsf.edu). OBJECTIVE. Appendiceal CT was introduced at our hospital in 1996 and now is used in most patients. The use of appendiceal CT has generated controversy and mixed results in var- ious investigations. Our purpose was to determine the percentage of patients for whom CT was performed, incidence of appendicitis, accuracy of CT, percentage of equivocal interpretations, and negative appendectomy rates for those patients who did and did not undergo CT. MATERIALS AND METHODS. Patient records from 2001 that included clinical or CT preoperative examination were analyzed, with follow-up through 2003. Patient age and sex, clinical presentation, CT techniques, CT interpretations, operative reports, pathology reports, and patient disposition were determined. Final diagnoses were provided by pathologic criteria, patient follow-up, or patient survey. Statistical analysis included Fisher’s exact test and re- ceiver operating characteristic (ROC) curves. RESULTS. Of 753 patients, 663 (88%) were examined on CT for suspected appendicitis and 90 had an appendectomy without undergoing CT. The incidence of appendicitis in the pa- tients who underwent CT was 39.2%. The sensitivity and specificity of CT were 99% and 95%, respectively; the area under the ROC curve was 0.9896; and the percentage of equivocal CT interpretations was 3.3%. The false-negative appendectomy rates were 3.0% and 5.6% for pa- tients with and without CT, respectively (for all patients, p = 0.326; for female pediatric pa- tients, p = 0.030). CONCLUSION. Five years ago, the negative appendectomy rate dropped from 20% to 7%, and it is now 3.0%. The incidence of appendicitis in patients who are examined on CT is stable compared with similar cohorts from prior investigations. Patients who do not undergo CT also have a low negative appendectomy rate, but this relatively small group is selected on the basis of a convincing clinical presentation. Female pediatric patients likely would have a lower negative appendectomy rate with greater use of CT. n 1996, appendiceal CT was intro- duced in the emergency depart- ment of a tertiary care hospital for patients admitted with suspected appendicitis. High accuracy and reduction in the negative appendectomy rate from 20% to approximately 7% were found during an early investigation of appendiceal CT [1]. By 2001, appendiceal CT was used in most patients with suspected appendicitis and was fre- quently requested by both surgeons and emer- gency physicians before deciding whether to admit the patient. Some patients went directly to surgery without CT. Conflicting reports concerning the effec- tiveness of CT in reducing the negative ap- pendectomy rate have appeared in the literature. Some investigations have found beneficial results, whereas others have found little change in the negative appendectomy rate [2–15]. The purpose of this investigation was to determine the status of appendiceal CT 5 years after its introduction including deter- mination of the percentage of patients with suspected appendicitis who underwent CT as a part of their diagnostic evaluation; the inci- dence of appendicitis in those patients who had CT; the sensitivity, specificity, and re- ceiver operating characteristic (ROC) curve of appendiceal CT in routine practice; the per- centage of equivocal CT interpretations; and the negative appendectomy rates for those pa- tients who had CT and those patients who went to surgery without CT. Materials and Methods The hospital institutional review board ap- proved this investigation. A retrospective review of I Downloaded from www.ajronline.org by 52.73.204.196 on 05/17/22 from IP address 52.73.204.196. Copyright ARRS. For personal use only; all rights reserved