Can outer-to-outer diameter be used alone in diagnosing appendicitis on 128-slice MDCT?

Figure 5 Thirty-five-year-old woman with history of asymptomatic hematuria. Normal appendix was not visualized on non-contrast study due to fluid distended adjacent bowel and paucity of intra-abdominal fat. Above shown post intravenous contrast computed tomography of the same patient later helped identify a fluid-filled appendix of 6.0 mm diameter (arrow).