动态CT增强扫描对孤立性肺结节的诊断价值

The diagnostic value of dynamic CT in solitary pulmonary nodules: a prospective study

目的采用动态CT增强扫描方法,探讨良恶性孤立性肺结节(SPN)的动态强化特点,以期提高SPN的诊断准确率。方法对51例SPN患者行同层动态CT增强扫描,造影剂总量100ml,注射速度4ml/s,延迟15s开始扫描,至120s结束。对动态CT扫描图像进行分析、密度测量,建立时间2密度曲线(TAC)。以双盲法分析CT扫描横断面图像及动态CT扫描结果。结果恶性SPN38例;良性SPN1(慢性炎症、增殖型结核、硬化性血管瘤)6例;良性SPN2(结核球、囊肿、隔离症、霉菌球)7例。恶性SPN强化程度明显大于良性SPN2,前者强化峰值(87.6)明显高于后者(57.80;P<0.01),强化值(峰值-平扫值;59.6)亦明显高于后者(11.1;P<0.01)。恶性SPN强化程度与良性SPN1相似,强化峰值、强化值在两者之间差异无统计学意义。恶性SPNTAC在形成陡峭的上升支后有一较长的平台期;良性SPN1的TAC与恶性相似,但上升支平缓,部分良性SPN1TAC可见降支形成;而良性SPN-TAC低平。以20HU为阈值,强化值≤20HU定为良性病变,>20HU定为恶性病变,其敏感性为100%,特异性为54.0%,准确性为88.4%。结论SPN强化的特性参数为峰值及强化值,其有助于良恶性病变的鉴别诊断;以强化值20HU为阈值,当强化值≤20HU时,一般可诊断为良性病变;TAC形态有助于SPN的定性诊断,恶性SPN曲线无明显降支,部分炎性病变可?

Objective To evaluate imaging features of benign and malignant solitary pulmonary nodules (SPN) using dynamic computed tomography (dCT) to improve the accuracy of radiological diagnosis. MethodsFifty one patients with SPN were studied by dCT. In this procedure, a bolus of 100 ml contrast medium was administrated intravenously at a rate of 4 ml/sec. The same located dynamic scans were carried out from 15 sec to 120 sec following the injection. Time attenuation curves (TAC) were created according to circular or oval ROI drawn over nodules. Histopathological diagnosis was considered as the golden standard in all patients. Double blind examination and evaluation were carried out and the data were analyzed statistically with Mann Whitney U test. Results Thirty eight cases were diagnosed to be malignant SPN (mSPN) and 13 cases to be benign SPN(bSPN). The benign SPN were further divided into two groups, bSPN 1 consisting 6 cases with chronic pneumonitis, nodular tuberculosis or sclerosing hemangioma and bSPN 2 consisting 7 cases with tuberculoma, pulmonary cyst, pulmonary sequestration or mycosis ball. There were statistically significant differences between mSPN and bSPN 2 in peak heights of enhancement(87.6 HU vs. 57.8 HU, P <0.01),enhancement values(peak heights unenhanced CT values, 59.6 HU vs. 11.1 HU, P <0.01).However,no statistically significant differences of those two values existed between mSPN and bSPN 1. TAC of mSPN reached to peak height more rapidly and remained a plateau. TAC of bSPN 1s showed similar changes to that of mSPN despite a delayed reach to a peak height or even a descending branch. TAC of the bSPN 2s was lower and flatter without peak height. If a threshold of 20 HU was taken for dCT, the lesions with ≤20 HU were diagnosed as benign, and the lesions with >20 HU were diagnosed as malignant, with a sensitivity of 100%, a specificity of 54.0% and an accuracy of 88.4%. Conclusion (1) Absence of the marked enhancement (≤20 HU) in dynamic CT is strongly predictive of benignancy. (2) The peak height and enhancement value of dCT are helpful to differentiate malignant SPNs from benign ones. (3) The TAC configuration is helpful in differentiating malignant SPNs from benign ones. Descending branches could be found in some benign lesions, but not in the malignant ones. The TAC of tuberculoma and mycosis ball is usually relatively low and flat without any peak height.