Ｓ状結腸・直腸穿孔のＣＴ診断で最も大事なことは，正確に直腸→Ｓ状結腸→下行結腸へ，または下行結腸→Ｓ状結腸→直腸を正確に追跡し，それらの腸管周囲のわずかな所見をも見落とさずいかに読影するかである．正確に追跡できないと正常腸管の所見なのか異常所見なのか判断できないことが多いので，腸管を追跡する訓練を十分積むことが診断力向上のカギとなる．
図１２の直腸1から頭側へ腸管壁の所見と腸管周囲の所見に注意しながら追ってみると，図８の6あたりからＳ状結腸で，図６の8〜図８の12のＳ状結腸はdensityの低い部分（粘膜下浮腫）により壁肥厚し，図４の16から下行結腸となり頭側へ上行する．図９〜図４のＳ状結腸の背側を占拠する△は図９と図４で盲端となるので腸管外の病変である．ニボー（air-fluid-level）を形成しているので前方のガスは遊離ガスで，背側の液状物質内の泡沫状のガスは前方腹壁側へ上昇できないガスで，糞便内ガスか食物残渣間に存在するガスと解釈され，すなわち病変△は腸管内容物が腸管外に排出され貯留したものである．辺縁はよく造影される明白な膿瘍壁を認めず，まだ新鮮な消化管穿孔であり，浮腫状に壁肥厚したＳ状結腸に包囲されているので穿孔部位はＳ状結腸であろうと診断する．図１，図３，図４，図６，図７と図９に憩室を認め（↑） ，Ｓ状結腸の限局した壁肥厚があり，Ｓ状結腸憩室炎の穿孔と診断する．抗生物質に反応せず3日後手術となった．Ｓ状結腸部分切除（Hartmann手術）と膿瘍ドレナージを行った．病理：sigmoid diverticulitis with perforation，compatible．

文献考察:憩室炎のCT所見
Kircher MF, Rhea JT, Kihiczak D, Novelline RA.
Frequency, sensitivity, and specificity of individual signs of diverticulitis on thin-section helical CT with colonic contrast material: experience with 312 cases.
AJR Am J Roentgenol. 2002 Jun;178(6):1313-8.

OBJECTIVE: The aim of our study was to determine the frequency, sensitivity, and specificity of the individual signs of diverticulitis using helical CT with colonic contrast material. MATERIALS AND METHODS: Between March 1997 and September 1999, 312 patients with suspected diverticulitis were examined on helical CT using rectally administered colonic contrast material. CT scans that were positive for diverticulitis or indeterminate were rereviewed by two radiologists; CT interpretations were correlated with patients' clinical courses and surgical findings. RESULTS: One hundred fourteen (37%) of the 312 CT scans were interpreted as positive for diverticulitis; 192 scans (61%), as negative; six scans (2%), as indeterminate. Of the 114 scans that were positive for diverticulitis, 109 (96%; sensitivity 96%, specificity 91%) showed bowel wall thickening; 108 (95%; sensitivity 96%, specificity 90%), fat stranding(脂肪組織のスジ状の濃度上昇）; 104 (91%; sensitivity 91%, specificity 67%), diverticula; 57 (50%; sensitivity 50%, specificity 100%), fascial thickening; 51 (45%; sensitivity 45%, specificity 97%), free fluid; 49 (43%; sensitivity 43%, specificity 100%), inflamed diverticula; 34 (30%; sensitivity 30%, specificity 100%), free air; 18 (16%; sensitivity 16%, specificity 100%), "arrowhead" signs; nine (8%; sensitivity 8%, specificity 99%), abscesses; four (4%; sensitivity 4%, specificity 100%,), phlegmons; five (4%; sensitivity 4%, specificity 99%), intramural air; two (2%; sensitivity 2%, specificity 100%), intramural sinus tracts. Overall CT interpretation had a sensitivity of 99%, a specificity of 99%, a positive predictive value of 99%, a negative predictive value of 99%, and an overall accuracy of 99%. CONCLUSION: The two most frequent signs of diverticulitis were bowel wall thickening (96%) and fat stranding (95%). Less frequent but highly specific signs were fascial thickening (50%), free fluid (45%), and inflamed diverticula (43%). PMID: 12034590 [PubMed - indexed for MEDLINE]