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目的评估在常规MR成像中扩散加权成像对壶腹癌诊断的附加价值。材料与方法该项回顾性研究获得了机构伦理委员会批准并免签知情同意书。纳入恶性壶腹部梗阻病人23例、良性壶腹部梗阻病人39例。根据所见的十二指肠乳头或其预估的位置进行定性(信号强度,强化类型)或定量[表观扩散系数(ADC)]分析。两名观察者独立地对常规MR成像和随后的常规与扩散加权联合的影像进行评估。采用五点评估法对壶腹癌的可能性进行评估。使用Fisher确切概率法和Mann-WhitneyU检验对两组间进行比较。对诊断性能(受试者操作特征曲线)、精确度、敏感度、特异度、阳性预测值(PPV)、阴性预测值(NPV)进行评估。结果在常规MR成像中,良性组内可见的或预计的十二指肠乳头所在区域表现为等信号(39例中有27~38例,占69%~97%),增强类型与正常十二指肠壁(39例中有27例,占69%)相似。上述表现良性组比恶性组(23例中有7~18例,占30%~78%)和常规MR成像组(23例中检出了3例,占13%)更常见。在扩散加权成像中,23例中有21例(91%)壶腹癌显示为高信号,而全部良性病例与正常十二指肠壁比较均表现为等信号(P<0.001)。壶腹癌的平均ADC值(1.23×10-3mm2/s)显著低于良性组(1.69×10-3mm2/s)(P<0.001)。两位观察者的诊断能力[ROC曲线下面积(Az)]在增加了扩散加权成像后显著提高。观察者1的Az提高至0.923~0.992(P=0.029),观察者2的Az提高至0.910~0.992(P=0.025)。此外,联合应用常规MRI与扩散加权成像的诊断精确度、敏感度、特异度、阳性预测值(PPV)、阴性预测值(NPV)显著高于单独应用常规MRI。结论与常规的MRI比较,常规MRI与扩散加权成像联合应用可以显著提高壶腹癌的检测率。
Objective To assess the added value of diffusion-weighted imaging in the diagnosis of ampullary carcinoma in conventional MR imaging. Materials and Methods The retrospective study was approved by the Institutional Ethics Committee and signed without consent. Including malignant ampulla obstruction in 23 patients, benign ampullary obstruction in 39 patients. Qualitative (signal intensity, fortification type) or quantitative [apparent diffusion coefficient (ADC)] analyzes were performed based on the duodenal papilla seen or their estimated location. Two observers independently evaluated conventional MR imaging followed by conventional and diffusion weighted imaging. Five-point assessment was used to evaluate the possibility of ampullary cancer. The Fisher exact test and the Mann-Whitney U test were used to compare the two groups. Diagnostic performance (receiver operating characteristic curve), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were evaluated. Results In conventional MR imaging, the region of the duodenal papilla visible or predicted in the benign group showed equal signals (27 to 38 of 39, 69% to 97% of the 39 cases), and the type of enhancement was similar to that of the normal 12 The bowel wall (27 of 39 cases, 69%) was similar. The above-mentioned benign group was more common than the malignant group (7-18 cases, 30% -78% of 23 cases) and conventional MR imaging group (3 cases were detected in 13 cases, accounting for 13%). In diffuse weighted imaging, amputation of 21 cases (91%) showed high signal in 23 cases, and all benign cases showed equal signal (P <0.001) compared with normal duodenal wall. The average ADC value of ampullary carcinoma (1.23 × 10-3 mm2 / s) was significantly lower than that of the benign group (1.69 × 10-3 mm2 / s) (P <0.001). The diagnostic power of both observers [area under the ROC curve (Az)] increased significantly after diffusion-weighted imaging was added. Az of observer 1 increased from 0.923 to 0.992 (P = 0.029) and Az of observer 2 increased from 0.910 to 0.992 (P = 0.025). In addition, the diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of combined conventional MRI and diffusion-weighted imaging were significantly higher than those of conventional MRI alone. Conclusion Compared with conventional MRI, the combination of conventional MRI and diffusion weighted imaging can significantly improve the detection rate of ampullary carcinoma.