急性胰腺炎患者坏死性积聚的CT和MRI特征及转归分析

CT and MRI Features and Prognosis of Acute Necrotic Collectionsin Patients with Acute Pancreatitis

目的:总结急性坏死性胰腺炎(ANP)患者局部并发症急性坏死性积聚(ANC)的影像特征,探讨影响ANC转归的因素。方法:回顾性分析31例ANP患者的临床及影像资料,在CT或MRI上观察ANC的影像特点,将其转归分为吸收组与包裹性坏死(WON)组,采用卡方检验比较两组间差异的统计学意义。结果:31例ANC平扫CT均呈斑片状不均匀低密度影,其内见小灶性类圆形等、低密度混杂影(23例)及脂肪低密度影(22例);19例ANC在平扫MRI均呈T1混杂低信号、T2混杂较高信号,其内FS T2WI可见低信号碎片影。3例(9.7%)合并局部感染,12例(38.7%)合并出血。增强扫描坏死组织无强化,其周边可有不同程度的斑片状或线样强化。对31例ANP患者随访(中位137天)显示,12例(38.7%)ANC完全吸收,19例(61.3%)形成WON,吸收组与WON组在坏死是否累及胰腺、累及胰腺部位、坏死体积、MCTSI评分的差异有统计学意义。结论:ANC在CT表现为不均匀液体密度,MRI呈不均匀信号影,增强扫描坏死组织无强化,但其周边组织可有不同程度强化改变。随访显示ANC可完全吸收或形成WON,并与多个影像因素相关。

Objective:To summarize the imaging features of acute necrotic collections(ANC),a local complication of acute necrotizing pancreatitis(ANP),and to explore the factors affecting the prognosis of patients with ANC.Methods:The clinical and imaging data of 31 patients with ANP were analyzed retrospectively.Characteristics of ANC on computed tomography(CT)and magnetic resonance imaging(MRI)were analyzed as well.Based on the follow-up outcomes,patients were divided into the absorption group and the walled-off necrosis(WON)group;a chi-square test was used to compare the two.Results:Plain CT revealed patchy,uneven,low-density shadows in 31 cases of ANC(focal,oval,and iso-density and low-density mixed shadows:23 cases;fatty low-density shadows:22 cases).Plain MRI revealed mixed low-signal intensities on T1-weighted imaging and mixed high-signal intensities on T2-weighted imaging in 19 cases of ANC;low-signal fragments were seen on Fat suppressed T2-weighted imaging in some of these cases.ANC was complicated with local infection and hemorrhage in 3(9.7%)and 12(38.7%)cases,respectively.The necrotic tissues did not show any enhancement,but the surrounding tissues appeared patchy or linear-enhancing changes with varying degrees on enhanced scans.Follow-up examination(median:137 days)revealed that ANC was completely absorbed in 12 cases(38.7%)and had developed into WON in 19 cases(61.3%).The absorption and WON groups differed significantly in terms of necrosis involving the pancreas,affected locations of the pancreas,necrotic volumes,and the modified CT severity index scores.Conclusion:On CT and MRI,ANC appears as uneven liquid densities and heterogeneous signal intensities,respectively.The necrotic tissue itself has no enhancement,but its surrounding tissue presents with different degrees of enhancing changes on enhanced scanning.Follow-up findings reveal that ANC can completely dissipate or progress to WON,which is related to several imaging factors.