Visualization rate and pattern of normal appendix on multidetector computed tomography by using multiplanar reformation display

Objective: To evaluate the visualization rate and describe the morphologic pattern of the normal appendix on multidetector CT (MDCT) by using multiplanar reformation display. Methods: We conducted a retrospective evaluation of the normal appendix with MDCT in 108 consecutive patients. A radiologist blinded to patient surgery history reviewed multiplanar reformation images at the workstation. The coronal and sagittal reformation images were reviewed in addition to the axial images. The visualization rate and morphologic pattern (including location, diameter, and lumen content) of normal appendices were recorded. Results: The prevalence of appendectomy was 9% (10 of 108 patients). The appendix was recorded as definitely visualized in 91 of 98 patients who denied a history of appendectomy, definitely not visualized in 13 patients, and unsure in 4 patients. For statistical analysis, the definitely not visualized and unsure cases were summed and categorized as not visualized. The sensitivity, specificity, positive and negative predictive values, and accuracy of visualization of the normal appendix by MDCT were 93%, 100%, 100%, 59%, and 94%, respectively. All the patients in the unsure group had ascites or inadequate pericecal fat, or both. The mean outer diameter of the appendix was 5.6 +/- 1.3 mm (SD) (range: 3.0-11.0 mm). Conclusion: We verify a high visualization rate (93%) of normal appendices on MDCT by using multiplanar reformation display.