基于腹部横截面积的低剂量CT扫描诊断急性阑尾炎的可行性

Feasibility of low-dose CT based on abdominal cross-sectional area in diagnosis of acute appendicitis

目的探讨基于腹部横截面积的低管电压CT扫描诊断急性阑尾炎的可行性。方法对临床拟诊为急性阑尾炎的患者行腹部CT检查,根据患者的腹部横截面积(s)分为3组:大面积组(A组),s≥600cm^2;中等面积组(B组),400cm^2≤s<600cm^2;小面积组(C组),s<400cm^2,分别采用120、100、80kV管电压行螺旋CT扫描。对3组不同辐射剂量扫描图像进行评价并作出影像学诊断,记录3组的剂量长度乘积(DLP)和CT容积剂量指数(CTDIvol),最终均经手术病理确诊,比较3组中CT诊断急性阑尾炎的效能。结果A、B、C组患者腹部横截面积差异有统计学意义(F=234.07,P<0.01),DLP分别为(424.51±40.28)mGy·cm、(201.57±9.23)mGy·cm、(134.12±8.91)mGy·cm,差异有统计学意义(F=1 171.19,P<0.01);CTDIvol分别为(10.39±0.61)mGy、(5.02±0.62)mGy、(3.37±0.07)mGy,差异亦有统计学意义(F=2 439.17,P<0.01),3组间两两比较DLP和CTDIvol值差异均有统计学意义(P均<0.01)。3组中CT诊断急性阑尾炎与术后病理结果的差异均无统计学意义(P均>0.05),敏感度、特异度、阳性预测值、阴性预测值及符合率分别为100%(32/32)、66.67%(2/3)、96.97%(32/33)、100%(2/2)、97.14%(34/35),92.50%(37/40)、100%(2/2)、100%(37/37)、40.00%(2/5)、92.86%(39/42),83.33%(15/18)、100%(5/5)、100%(15/15)、62.50%(5/8)、86.96%(20/23)。结论根据患者腹部横截面积差异采用不同管电压的腹部低剂量扫描方案可降低患者的辐射剂量,亦可用以诊断急性阑尾炎。

Objective To explore the feasibility of low-dose CT in diagnosis of acute appendicitis by reducing the tube voltage based on abdominal cross-sectional area.Methods According to abdominal cross-sectional area（s）,the patients suspected of acute appendicitis were divided into 3 groups at large area（group A,s≥600cm^2）or medium area（group B,400cm^2≤s600cm^2）or small area（group C,s400cm^2）,undergoing 64-MDCT with 120,100,80 kV,respectively.The dose-length product（DLP）and CT dose index volume（CTDIvol）of 3groups were recorded.The image quality and diagnosis was evaluated.All cases were confirmed by operation and pathology.The CT diagnosis efficiency of acute appendicitis were compared among 3 groups.Results There was significant difference in abdominal cross-sectional area among three groups（F=234.07,P0.01）.The DLP of the three groups were（424.51±40.28）mGy·cm,（201.57±9.23）mGy·cm,（134.12±8.91）mGy·cm（F=1 171.19,P0.01）,and the CTDIvol were（10.39±0.61）mGy,（5.02±0.62）mGy,（3.37±0.07）mGy（F=2 439.17,P0.01）.There was significant difference between arbitrary two of the three groups,respectively（all P0.01）.There was no significant difference between the CT diagnosis and postoperative pathology in three groups（all P0.05）.The sensitivity,specificity,positive predictive value,negative predictive value and accuracy of them were 100%（32/32）,66.67%（2/3）,96.97%（32/33）,100%（2/2）,97.14%（34/35）and92.50%（37/40）,100%（2/2）,100%（37/37）,40.00%（2/5）,92.86%（39/42）and 83.33%（15/18）,100%（5/5）,100%（15/15）,62.50%（5/8）,86.96%（20/23）,respectively.Conclusion The CT scanning program of low-dose with different tube voltage based on abdominal cross-sectional area can be used to reduce radiation dose and it is feasible in diagnosis of acute appendicitis.