右側結腸（A：上行結腸，C：盲腸）は図９で盲端になり，図２のガスで拡張したTIが回腸末端と思われ，尾側へ下行する．図８の１〜図６の１５が2回Uターンする虫垂である．壁は強く造影され，最大1cm以上に腫大し急性虫垂炎であるが，腹腔内脂肪組織が少ないため周囲の炎症所見に乏しい症例である．病理：急性虫垂炎，moderate acute inflammation．

参考症例（Plain CT，5mmスライス，急性虫垂炎）：73歳女性．2日前から続く右下腹部痛，食欲不振と微熱のため来院した．体温：36.8℃，右下腹部に圧痛があるが，反跳痛や筋性防御はない．
単純CTだが，腸管周囲に脂肪組織が豊富だから診断は容易である．盲腸（C）は図６で盲端になり，図１〜図９のTIが回腸末端である．図６の１が虫垂根部で，数字順に展開し図１０の５で盲端になる．1ｃｍ以上に腫大し，図５〜図７で周囲脂肪組織の濃度上昇（△）を認め，急性虫垂炎である．手術・病理所見：phlegmonous appendicitis（図A）．

文献考察：CTの急性虫垂炎診断の精度は97.6%．
AJR Am J Roentgenol. 2002 Jun;178(6):1319-25.
Accuracy of nonfocused helical CT for the diagnosis of acute appendicitis: a 5-year review.
Raman SS, Lu DS, Kadell BM, Vodopich DJ, Sayre J, Cryer H.
OBJECTIVE: The clinical usefulness of routine, nonfocused helical CT was evaluated in diagnosing acute appendicitis or providing an alternative diagnosis in patients presenting to the emergency department with acute lower abdominal pain. MATERIALS AND METHODS: We reviewed CT reports and clinical records of 650 consecutive adult patients who presented between January 1996 and December 2000 with right lower quadrant pain or lower abdominal pain and clinical findings suggestive of appendicitis. Helical CT was performed with oral contrast material in 610 cases (93.8%) and IV contrast in 572 cases (88.0%). Both vascular and enteric contrast media were administered in 544 cases (83.7%). Rectal contrast material was administered in 52 cases (8.0%). The abdomen was helically scanned from the dome of the diaphragm to the iliac crests with a collimation of 7 mm, from the iliac crests to the acetabular roof at a 5-mm collimation, from the acetabular roof to the symphysis pubis with a collimation of 5-10 mm. The surgical or clinical record was used for follow-up. RESULTS: Of the 650 patients, 552 (84.9%) had adequate clinical follow-up. There were 137 true-positive, eight false-positive, five false-negative, and 402 true-negative cases. The sensitivity, specificity, and accuracy of nonfocused helical CT were 96.5%, 98.0%, 97.6%, respectively. The positive and negative predictive values were 94.5% and 98.8%, respectively. In patients without acute appendicitis, CT suggested an alternative diagnosis, which clinically explained the patient's acute abdominal pain in 266 patients (66.2%). CONCLUSION: Nonfocused helical CT was highly accurate in diagnosing acute appendicitis or suggesting an alternative diagnosis in patients with acute lower abdominal pain or right lower quadrant pain.PMID: 12034591