MRI表观扩散系数对乳腺非肿块样病灶的诊断价值

目的评价表观扩散系数对乳腺MRI非肿块样强化病灶的诊断价值及其与时间信号强度曲线联合应用对诊断效能的影响。方法 68个经手术病理证实的乳腺病灶,根据其不同强化形态分为肿块型与非肿块型两组。测量病灶时间-信号强度曲线并记录曲线类型,并于b=800 s/mm2扩散加权图像上测量病灶ADC值。利用两独立样本t检验比较同一强化形态组中良恶性病灶ADC值的差异。分别绘制曲线类型及ADC值诊断病灶良恶性的ROC曲线,计算曲线下面积、最佳截断点、敏感性、特异性、准确性、阳性预测值、阴性预测值。分析对不同强化形态的病灶,以ADC值作为曲线类型的辅助诊断指标对诊断效能的影响。结果肿块型组中恶性病灶ADC值(0.85±0.09)×10-3mm2/s明显低于良性病灶(1.68±0.32)×10-3mm2/s(P=0.001),非肿块型组中恶性病灶ADC值(1.02±0.19)×10-3 mm2/s亦明显低于良性病灶(1.43±0.31)×10-3 mm2/s(P=0.015)。同一强化形态组,曲线类型与ADC值的ROC曲线下面积均无显著性差异(P值均小于0.05)。对于肿块型组,以ADC值作为曲线类型的辅助诊断指标,诊断效能无显著改变(P=0.549),但可以提高诊断的特异性和阳性预测值(准确性达100%);对于非肿块型组,以ADC值作为曲线类型的辅助诊断工具,诊断效能无显著改变(P=0.709),但可以提高诊断的准确性至87.5%,敏感性和阴性预测值达100%。结论 ADC值对不同强化形态的病灶有辅助诊断作用。

MRI apprent diffusion coefficient for discriminating benign and malignant breast non-mass like lesions

Objective To determine whether lesion type affect discrimination of benign and malignant breast lesions with diffusion-weighted MRI and whether DWI as an adjunct to time-signal curve can improve diagnostic performance. Methods This study included 68 breast lesions identified with dynamic contrast-enhanced MRI. Diffusion-weighted ima- ges were acquired during clinical breast MRI at b values of 0 and 800 s/mm^2. Differences in the apparent diffusion coeffi- cients （ADC） of benign and malignant lesions were compared by lesion type （mass or non-mass like enhancement） , and receiver operating characteristics analysis was performed to evaluate diagnostic performance based on ADC thresholds and time-signal curve types. Combined the ADC value criteria with the type of time-signal curve to diagnosis benign and mali- gant breast lesions. Results The mean ADC was significantly lower for malignant than for benign lesions for both masses（ （0. 85 ±0. 09）^-3mm^2/s for malignant, （ 1. 68 ±0. 32）^-3mm^2/s for benign; P = 0. 001 ） and lesions with non-mass like enhancement （ （ 1.02 ±0. 19）^-3mm^2/s for malignant, （ 1.43 ±0. 31 ） ^-3mm^2/s for benign; P = 0. 015 ）. There was no differenees in area under the receiver operating eharaeteristies curve （AUC） based on ADC val- ues and time-signal curve types on both type groups （ P 〉 0, 05 ）. Combining the ADC value criteria with the type of time- signal curve increased specificity and postive predictive value （PPV） to 100% for mass group, and increased aeeuraey to 87.5% , sensitivity and negative predictive value （NPV） to 100%. Conclusion Use of ADC values does not adequately improve the type of time-signal eurve performanee for differential diagnosis of mass-like and non-mass-like breast lesions, but adding the ADC value criteria to the type of time-signal curve analysis improves specificity, PPV for mass-like lesions, and improves sensitivity, NPV, and aeeuraey.