低剂量扫描迭代重建联合胆道重建技术在胆总管占位性病变诊断中的价值

Value of iterative reconstruction technique combined with biliary reconstruction in diagnosis of common bile duct lesions

目的:探讨iDose^4迭代算法低管电压对胆总管占位性病变图像质量和噪声的影响,并联合胆道重建技术提高胆总管占位性病变的诊断效能.方法:搜集临床或超声疑诊为胆总管占位的患者27例进行门静脉期后的第三期的低剂量扫描,并分别进行滤波反投影技术(filtered back projection,FBP)和iDose^4重建,通过对重建后的图像进行胆道重建以明确病变,用统计学方法分析低管电压扫描的剂量降低的幅度、两种重建方式的图像质量差异和诊断效能.结果:100 kV条件下iDose^4重建后的图像的诊断效能高于FBP重建后的图像,且差异具有统计学意义(P<0.05).低剂量iDose^4重建算法较常规剂量扫描降低辐射剂量约37.6%.iDose^4重建后的图像的肝脏、胆管、壶腹周围的噪声较常规FBP重建在层厚为1 mm和5 mm时分别降低了31.23%(1mm)和23.54%(5 mm)、32.12%(1 mm)和20.36%(5 mm)、34.95%(1 mm)和29.45%(5mm).以肝脏作为对比,CNR较FBP升高了31.67%(1 mm)和21.74%(5 mm);以壶腹部作为对比,iDose^4重建病变的CNR较FBP升高了45.10%(1 mm)和43.10%(5 mm).低剂量组的iDose^4重建后的图像评分均明显高于FBP重建,且差异具有统计学意义(P<0.05).低剂量组的iDose^4重建后的图像的评分稍低于常规剂量FBP组,但差异不具有统计学意义(P>0.05).结论:在保证图像质量的前提下,相比常规剂量FBP重建,低剂量iDose^4迭代重建算法可明显降低辐射剂量;与低剂量FBP重建比较,低剂量iDose^4重建可提供较好图像质量;联合胆道重建技术对病变的显示更佳,从而提高胆总管占位性病变的诊断效能.

AIM：To explore the effect of iterative algorithm（iDose algorithm） with low tube voltage on image quality and noise in common bile duct lesions,and improve the diagnosis of bile duct lesions by combining with biliary reconstruction technology.METHODS：Twenty-seven patients with proven common bile duct lesions by clinical symptoms or ultrasonography underwent low dose computed tomography（CT） scans in the third phase after the portal phase.All images of the third phase were reconstructed by conventional FBP and iDose^4,which were used to reconstruct the biliary system to show lesions clearly.Radiation dose,image quality and diagnostic accuracy of images reconstructed by FBP and iDose^4 were analyzed by statistical method.RESULTS：Diagnostic accuracy of images reconstructed by iDose^4 with 100 kV was significantly higher than that of images reconstructed by FBP（P〈0.05）.Compared with routine-dose scan of portal phase,radiation dose of the low-dose scan was reduced by 37.6%.Image noise of the liver,common bile duct and ampulla reconstructed by iDose^4 was decreased by 31.23%（1 mm）and 23.54%（5 mm）,32.12%（1 mm） and20.36%（5 mm）,34.95%（1 mm） and 29.45%（5 mm）,respectively,compared with images reconstructed by FBP.In contrast to the liver,CNR of images reconstructed by iDose^4 was increased by 31.67%（1 mm） and 21.74%（5mm）.In contrast to the ampulla,CNR ofimages reconstructed by iDose^4 was increased by 45.10%（1 mm） and 43.10%（5 mm）.Image scores of images reconstructed by iDose^4 with low dose were significantly higher than those of images reconstructed by FBP with low dose（P〈0.05）.However,image scores of images reconstructed by iDose^4 with low dose were lower than those of images reconstructed by FBP with routine dose,but there were no significant differences（P〈0.05）.CONCLUSION：In premise of ensuring image quality,low-dose CT with iDose^4 reconstruction can decrease radiation dose significantly compared with routine-dose CT with FBP reconstruction.Compared with low-dose FBP reconstruction,low-dose iDose^4 reconstruction could improve image quality.In addition,biliary reconstruction can improve the display of lesions,which can improve the diagnosis of common bile duct lesions.