田中 幸子, 高倉 玲奈, 井岡 達也, 仲尾 美穂, 福田 順子, 鈴木 玲子, 上田 絵里, 吉岡 二三, 蘆田 玲子, 有本 伸子

Sachiko TANAKA, Rena TAKAKURA, Tatsuya IOKA, Miho NAKAO, Junko FUKUDA, Reiko SUZUKI, Eri UEDA, Fumi YOSHIOKA, Reiko ASHIDA, Nobuko ARIMOTO

地方独立行政法人大阪府立病院機構大阪府立成人病センター検診部

Department of Cancer Survey, Osaka Medical Center for Cancer & CVD

キーワード : pancreas cancer, high-risk group, low-dose plain CT, ultrasonography, health checkup

目的：超音波検査と低線量非造影Ｘ線CTとによる膵嚢胞及び主膵管拡張の検出能の比較を行う．対象と方法：対象は2009年4月以降の21ヵ月間に当院入院健診を受診した544例で全例に腹部超音波検査及び非造影低線量CTによる膵の画像診断を行った．いずれかで膵嚢胞あるいは主膵管拡張を指摘した109例に対してMRCPあるいは造影MDCTによる二次検査を行い超音波検査及び非造影低線量CTによる両所見の検出能を比較検討した．結果と考察：最大径5 mm以上の嚢胞は55例（うち21例は多発），主膵管拡張は67例に認められた．US及びCTによる膵嚢胞存在の有無についての診断精度は，感度，特異度，精度がそれぞれ，US:96％，94％，95％，CT: 33％，94％，63％であった．特異度は同等，感度はUSが有意に優れていた（P＜0.0001）．最大嚢胞の大きさや存在部位にかかわらず，CTによる検出感度はUSのそれを超えることはなかった．主膵管の同定はUSでは膵体部にて100％（544/544）可能，CTでは0.7％（4/544）であった．主膵管拡張67例は全例USで径2.5 mm以上の拡張が指摘された．結論：膵癌高危険因子である膵嚢胞及び主膵管拡張の検出能は超音波検査が低線量非造影CTに比べ有意に優れていた．

Purpose: The presence of pancreatic cyst(s) and the main pancreatic duct dilatation are recognized to be high-risk signs of pancreas cancer. The purpose of this study is to compare ultrasonography and low-dose, non-contrast, enhanced X-ray CT in terms of the detectability of these findings. Subjects and Methods: Subjects were 544 people (346 men and 198 women, age range: 29-88 y.o., mean age: 64.1+10.2 y.o.) who underwent a health checkup during the 21-month period from April 2009 to the end of December 2010. For ultrasonography (US), the fluid-filled stomach method was additionally performed after ordinal abdominal scanning. And for CT, low-dose plain X-ray CT was employed, considering the aim was a health checkup. For 109 people in whom pancreatic cyst (≥5 mm in diameter) and/or pancreatic duct dilatation (≥2.5 mm at the body) were detected with US or CT, magnetic resonance pancreatography or multidetector contrast-enhanced CT was additionally performed within one month to evaluate the findings. Results and Discussion: The sensitivity, specificity, and overall accuracy for the detection of pancreatic cyst were 96%, 94%, and 95%, respectively, with ultrasonography, and 33%, 94%, and 63%, respectively, with CT. The sensitivity was statistically significantly higher (P〈0.0001) with ultrasonography than with low-dose plain CT, and the specificity was same. Regardless of the size or location, the detectability with low-dose plain CT did not exceed that with US. The main pancreatic duct was visualized in all 544 cases with US, but in only four cases (0.7%) with low-dose plain CT. The main pancreatic duct dilatation was confirmed with MRP or contrast-enhanced MDCT in all 67 cases in which it was detected by US. Conclusion: Ultrasonography showed significantly higher accuracy as compared with low-dose plain X-ray CT in the detection of pancreatic cysts and the main pancreatic duct dilatation. For the screening of these high-risk signs of pancreas cancer, the role of ultrasonography is considered to be important.