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目的探讨低剂量CT能否取代常规剂量CT检测妊娠滋养细胞肿瘤(GTT)患者的肺转移。方法 34例GTT患者进行了56次常规剂量(120KV,150 mAs,螺距1,标准重建算法)和低剂量(120 KV,40 mAs,螺距2,骨重建算法)胸部CT扫描。每次扫描获得的常规剂量和低剂量图像作为配对组,由2位医师分别阅读,各自记录肺部转移病灶的数目和大小。肺转移病灶定义为肺实质中不能用肺血管解释的肺结节。采用符号等级秩和检验比较两种扫描方式在病灶检出方面的差异。结果在常规剂量CT图像上发现肺部转移灶1417个,低剂量CT图像上发现转移灶1214个。低剂量扫描方案对于<5 mm的肺部转移病灶检出能力降低(Z=-3．368,P=0．000)。虽然小病灶容易在低剂量扫描被漏检,但不影响对疾病的预后评分,对分期的判断也有很高准确性。结论低剂量CT可以替代常规剂量CT用于GTT患者肺部转移的评估和随访。
Objective To investigate whether low-dose CT can replace lung metastases in patients with gestational trophoblastic tumor (GTT) by conventional dose CT. Methods Thirty-four patients with GTT underwent chest CT scan of 56 conventional doses (120KV, 150 mAs, pitch 1, standard reconstruction algorithm) and low dose (120 KV, 40 mAs, pitch 2, bone reconstruction algorithm). The conventional dose and low dose images obtained from each scan were used as a paired group and were read by 2 physicians, each recording the number and size of lung metastatic lesions. Lung metastases are defined as pulmonary nodules that can not be explained by pulmonary vessels in the parenchyma of the lung. The symbol rank rank sum test was used to compare the difference in lesion detection between the two scanning methods. Results 1417 pulmonary metastases were found on conventional CT images and 1214 metastases on low dose CT images. Low-dose scanning reduced the ability to detect lung metastases <5 mm (Z = -3.368, P = 0.000). Although small lesions are easily missed in low-dose scans, they do not affect the prognosis of the disease and have a high degree of accuracy in staging. Conclusion Low-dose CT can be used as an alternative to conventional dose CT in the assessment and follow-up of pulmonary metastases in patients with GTT.