文献考察:CTによる重症度Staging とCTSI(CT重症度指数)
Radiol Clin North Am. 2002 Dec;40(6):1199-209. Staging of acute pancreatitis.
Balthazar EJ.
Management of patients with acute pancreatitis is based on the early assessment of severity of disease. Initial staging is established on clinical and laboratory grounds and on the findings of contrast-enhanced CT imaging. Individual clinical parameters and laboratory indices, although sometimes helpful, are not sufficiently accurate to reliable assess the severity of an acute attack. Numerical grading systems (Ranson's, APACHE II) with sensitivities of about 70% are commonly used today as indicators of systemic failure and predictors of disease severity. Helical or MDCT scanning performed during the administration of a bolus of i.v. contrast material is performed to evaluate pancreatic morphology, detect pancreatic necrosis, and depict retroperitoneal complications. CT staging and the CT severity index have proved to be a reliable indicator of disease severity, having shown an excellent correlation with the risk of death and the development of local and systemic complications in this population.PMID: 12479706 要旨.Grade A:正常な膵所見,Grade B:膵腫大があり,辺縁の不整や膵実質の不整な濃度減少があるが周辺に炎症所見(浮腫)を伴わない,Grade C:Grade Bの所見に周囲脂肪組織の炎症所見を伴う,Grade D:膵周囲の少量の,1箇所だけの液貯留,Grade E:2箇所以上に液貯留,膵内または後腹膜腔にガスが存在する(表1).Grade A〜Grade Cだと死亡率は0%,合併症率は4%だったのと比べ,Grade DとGrade Eでは死亡率14%,合併症率54%と高い(図1).膵壊死の有無も予後に大いに関係あり(図2),膵壊死の程度を加味しCT Severity Index(CTSI:CT重症度指数)を考案した(表2).Grade A〜Grade Eをそれぞれ0点〜4点とし,膵壊死30%以下:2点加算,膵壊死30%〜50%:4点加算,膵壊死50%以上:6点を加算する.図3のごとくCTSIと比例して予後は悪くなる.
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