Journal of the Medical Association of Thailand Vol 93, No 12:DECEMBER 2010 0125-2208 93 12 2010 Dec Wall Thickness and Outer Diameter of the Normal Appendix in Adults Using 64 Slices Multidetector CT 1437 EN Aphinya Charoensak Sopa Pongpornsup Wanwarang Suthikeeree Original Article Determine wall thickness and outer diameter of the normal appendix in adults using 64 slices multidetector CT A retrospective review of 538 patients (190 men, 348 women; mean age, 56.5 years + 15.2 SD) whowere sent for abdomino-pelvic CT without clinical suspicion of acute appendicitis was conducted. Two radiologists blinded tothe presented patient’s history of appendectomy interpreted CT images regarding the visualization of the appendix, location,luminal contents and presence of appendicoliths. The maximum outer diameter and two walls thickness of the visualizedappendices were measured. The sensitivity, specificity, positive and negative predictive value, and accuracy for visualization of the appendix were90.8%, 100%, 100%, 76.5% and 92.9% for reader 1 and 97.3%, 97.6%, 99.3%, 91.7% and 97.4% for reader 2. The meanmaximum outer diameter of the appendix was 6.6 mm + 1.5 (range, 3.4-14.0 mm). The mean two walls thickness of theappendix was 4.4 mm + 1.0 (range, 1.6-8.0 mm). The normal appendix is frequently identified at 64 slices MDCT. Contrast to maximum outer diameter, normaltwo walls thickness of the appendix is infrequently exceeding the threshold of 6 mm. Computed tomography Multidetector Appendix Adults