Diagnosis of Acute Appendicitis: Comparison of 5- and 10-mm CT Sections in the Same Patient

PURPOSE: To compare 5- and 10-mm computed tomographic (CT) sections in the same patient to diagnose acute appendicitis. MATERIALS AND METHODS: During an 11-month period, 100 consecutive patients clinically suspected to have acute appendicitis underwent abdominal and pelvic CT. Helical, 10-mm-collimated sections from the diaphragm to the pubic symphysis and 5-mm-collimated sections through the lower part of the abdomen and upper part of the pelvis were obtained. The 10- and 5-mm sections from each patient were separated into two groups and were interpreted independently by two abdominal imaging attending physicians who were blinded to the final results. The interpretations were correlated with the histopathologic or final clinical diagnoses. RESULTS: Data analysis from blinded reader interpretations of the 5- and 10-mm sections, respectively, revealed sensitivities of 99% and 82% (P <.001), specificities of 98% and 95% (P =.426), and accuracies of 99% and 89% (P <.001). Among the 48 cases of acute appendicitis, abnormal appendices were identified in 94% (n = 45) and 69% (n = 33) (P <.05) on 5- and 10-mm-collimated sections, respectively. Right-lower-quadrant inflammatory changes were identified in 98% (n = 47) and 71% (n = 34) (P <.05) on 5- and 10-mm-collimated sections, respectively. Normal appendices were identified in 75% (n = 39) and 52% (n = 27) of the 52 negative cases on 5- and 10-mm sections (P =.025), respectively. CONCLUSION: Use of thin-section CT significantly improves the diagnosis of acute appendicitis.