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急性局灶性细菌性肾炎(acute focal bacterial nephritis, AFBN)为局限于肾实质内的无液化细菌性炎症,也称“大叶性肾炎”。儿童期发病的临床症状和体征均不典型,若能早期诊断则可避免发展至肾脓肿。影像学检查可反映患肾受累程度、范围及是否存在并发症,对于病变评估、预后及随访等具有重要的临床价值[1]。对于AFBN的诊断超声为首选检查,但其诊断的灵敏度及特异度均不高;CT增强检查由于存在电离辐射并需注射碘对比剂而使其应用相对受限。MRI增强检查对于AFBN的诊断灵敏度及特异度均较高,是目前应用较为广泛的影像学检查手段[2]。扩散加权成像(diffusion weighted imaging,DWI)技术能够无创性反映活体组织或器官的功能状态,并可通过测量表观扩散系数(apparent diffusion coefficient, ADC)对患肾进行定量评估[3]。我们就儿童AFBN的DWI影像学表现进行分析总结,评判其与钆(Gadolinium,Gd)-T1加权像(T1 weighted image,T1WI)增强扫描的诊断一致性,旨在评估其诊断效能,提高对该病的早期诊断能力。
儿童急性局灶性细菌性肾炎的DWI诊断价值
DWI diagnosis of acute focal bacterial nephritis in children
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摘要:
目的分析儿童急性局灶性细菌性肾炎(AFBN)的扩散加权成像(DWI)的影像学表现,并以钆-T1加权像(Gd-T1WI)增强检查为参考标准评估DWI对AFBN的诊断价值。 方法2016年2月至2017年12月经临床确诊为AFBN的患儿26例(男患儿12例、女患儿14例),均行磁共振检查,包括常规磁共振序列(T1WI、T2WI)、DWI及Gd-T1WI增强扫描,以Gd-T1WI增强表现来评定DWI诊断AFBN的灵敏度和特异度。应用Kappa检验和McNemar检验方法统计扫描序列之间的一致性和观察者之间的可重复性。 结果26例患儿中有24例在Gd-T1WI增强图像上表现出楔形低灌注区,21例单侧肾脏受累,3例双侧肾脏受累。26例患儿于DWI图像上均发现阳性结果,其中,23例单侧肾脏受累,3例双侧肾脏受累。病变在DWI上表现为高信号,表现扩散系数的平均值较正常肾组织减低。采用DWI检测病变的灵敏度和特异度分别为100%和92%。DWI与Gd-T1WI具有很好的一致性,对病灶的检测差异无统计学意义(k=0.923,P=0.25)。各观察者应用DWI检测病变具有很好的可重复性(k=0.76)。 结论DWI序列可明确诊断儿童AFBN,尤其是对肾功能不全、不宜使用对比剂者;其影像表现为楔形或片状高信号影,诊断有效性与MRI增强扫描基本一致。 Abstract:ObjectiveTo analyze the diffusion weighted imaging(DWI) manifestations of acute focal bacterial nephritis in children against the reference standard of gadolinium-enhanced T1-weighted imaging(Gd-T1WI). MethodsBetween February 2016 and December 2017, 26 cases of children (12 males, 14 females) with acute focal bacterial nephritis were examined by magnetic resonance(MR), including routine MR sequence(T1WI, T2WI), DWI, and Gd-T1WI-enhanced scan. The sensitivity and specificity of DWI in the diagnosis of acute focal bacterial nephritis were evaluated by Gd-T1WI-enhanced performance. Kappa test and McNemar test were applied for the calculation of the consistency among scanning sequences and calculation of repeatability among observers. ResultsAmong the 26 children, 24 cases showed a wedge-shaped hypoperfusion area in the enhanced Gd-T1WI images, 21 had unilateral renal involvement, and 3 had bilateral renal involvement. Twenty-six cases had positive results on DWI images, 23 had unilateral renal involvement, and 3 had bilateral renal involvement. The lesions showed high signal on DWI, and the mean apparent diffusion coefficient value is lower than that of the normal renal tissue. The sensitivity and specificity of DWI detection were 100% and 92%, respectively. DWI demonstrated excellent agreement(k=0.923) with Gd-T1WI with no significant difference(P=0.25) in detection of abnormal lesions. All the observers used DWI to detect lesions with excellent reproducibility(k=0.76). ConclusionsDWI can be used to diagnose acute focal bacterial nephritis with wedge-shaped or flaky high signal in children. The diagnostic effectiveness of DWI is basically the same as MRI enhanced scan, especially in people with renal insufficiency and inappropriate use of contrast agents. -
Key words:
- Child /
- Nephritis /
- Bacterial infections /
- Magnetic resonance imaging /
- Diffusion weighted imaging
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