Abstract: Background　At present，the diagnosis of pulmonary alveolar proteinosis（PAP） still needs bronchialveolar lavage and/or lung biopsy，which belongs to invasive examination.Chest CT plays an important role in the diagnosis of PAP，especially low-dose volume data high resolution CT（VHRCT），which can show more anatomical details and characteristics of lesions，thus providing help for clinical diagnosis.But there are few reports in this regard.Objective　To observe the imaging findings of PAP before and after treatment with low-dose VHRCT，and to explore the clinical value of low-dose VHRCT in PAP diagnosis.Methods　Clinical data，chest low-dose VHRCT data，diagnosis and treatment of 24 patients who were diagnosed as pulmonary alveolar proteinosis and treated in West China Fourth Hospital，Sichuan University from June 2015 to June 2018 were retrospectively analyzed.Results　Before treatment，24 patients had multiple ground-glass opacities with clear borders and blurred margins in both lungs；12 had wide distribution of ground-glass opacities，showing a geographic appearance；seven had localized patchy consolidation in both lungs；six had thickened interlobular septum，presenting crazy paving pattern；three had large area shadows outward projection from both hilus pulmonis，distributing like butterfly wings，and two had pneumatic bronchus sign.In some cases，multiple micro-nodules and interstitial fibrosis were seen in both lungs.No enlarged lymph nodes in mediastinum and hilus pulmonis was found in 24 cases.In the same case，the above-mentioned imaging findings appeared simultaneously.In the course of follow-up and review after treatment，these ground glass opacities of 24 cases were reduced in scope，decreased in density and clear in edge；four cases of consolidation shadow were transformed ground-glass opacity，two cases of pneumatic bronchial sign.Sixteen cases were diagnosed by bronchoalveolar lavage，three cases by serum granulocyte macrophage- colony stimulating factor（GM-CSF） antibody detection，and five cases by lung biopsy.According to VHRCT characteristics of PAP，16 cases were correctly diagnosed，with the accuracy rate of 66.7%（16/24）．Five cases were misdiagnosed as bacterial pneumonia，two cases as pulmonary edema and one case as idiopathic pulmonary interstitial fibrosis.After treatment，the clinical symptoms such as dyspnea and cough were relieved.Total lung capacity/estimated value（TLC%），diffusing capacity of the lungs for carbon monoxide/ estimated value（DLCO%），vital capacity / estimated value（VC%），pH，and oxygen partial pressure（PaO2） were higher after treatment，while the partial pressure of carbon dioxide（PaCO2） after treatment was lower than that before treatment（P<0.05）．Conclusion　The low-dose VHRCT of PAP showed ground glass opacity and/or consolidation with extensive or limited distribution.The “map pattern” and “crazy paving pattern” had certain characteristics，and some cases showed "butterfly wing pattern" and pneumatic bronchial sign.In addition，the disease generally had no enlargement of mediastinal and hilar lymph nodes.It is helpful for the diagnosis，severity evaluation and curative effect observation of pulmonary alveolar proteinosis，and can be used as a routine examination.

Key words: Pulmonary alveolar proteinosis, Volume data high resolution CT, Diagnosis

摘要： 背景　目前肺泡蛋白沉积症（PAP）的确诊需要依据支气管肺泡灌洗和/或肺活检，属于侵入性检查，而胸部CT检查对本病的诊断具有重要提示作用，尤其是胸部低剂量容积数据高分辨率CT（VHRCT）检查能更多地显示双肺解剖细节及病变细微特点，从而为临床诊断提供帮助，但鲜有这方面的报道。目的　观察低剂量VHRCT下PAP治疗前后的影像学表现，从而探讨VHRCT在PAP诊断中的临床价值。方法　回顾性分析2015年6月—2018年6月在四川大学华西第四医院诊治的24例PAP患者的临床资料和胸部低剂量VHRCT资料、确诊情况及治疗效果。结果　治疗前，24例患者双肺均可见多发的磨玻璃样密度影，边界清，边缘模糊，其中12例磨玻璃影广泛分布，呈“地图征”表现，7例患者双肺可见局限性片状实变影；6例磨玻璃影中可见小叶间隔增厚，呈“铺路石征”表现；3例可见从肺门向外放射，呈“蝶翼状”分布的大面积阴影（磨玻璃影或/和实变影）；2例可见充气支气管征；部分患者双肺可见多发微小结节及间质纤维化表现；24例均未见纵隔及肺门淋巴结增大；同一患者中可有上述几种征象同时出现。治疗后复查及随访过程中，24例双肺磨玻璃影范围不同程度缩小、密度减低、边缘清晰，4例实变影密度减低呈磨玻璃密度影，2例见充气支气管征。16例经支气管肺泡灌洗确诊，3例经血清粒细胞—巨噬细胞集落刺激因子（GM-CSF）抗体检测确诊，5例经支气管镜肺穿刺活检确诊。确诊前根据患者胸部低剂量VHRCT的特征性表现高度提示PAP者共16例，符合率为66.7%（16/24），其余8例患者依据VHRCT的特征，5例提示细菌性肺炎、2例提示肺水肿、1例提示特发性肺间质纤维化。治疗后患者，呼吸困难、咳嗽等临床症状明显好转。治疗后总肺活量占预计值百分比（TLC%）、一氧化碳弥散量占预计值百分比（DLCO%）、肺活量占预计值百分比（VC%）、酸碱度（pH）、氧分压（PaO2）高于治疗前，治疗后二氧化碳分压（PaCO2）低于治疗前（P<0.05）。结论　PAP的低剂量VHRCT表现为广泛性或局限性分布的磨玻璃影和/或实变影，其中“地图征”和“铺路石征”具有一定的特征性，部分病例可见“蝶翼征”和充气支气管征；另外，本疾病一般无纵隔及肺门淋巴结增大；上述影像学征象有助于PAP的诊断、严重程度评价和疗效观察，可作为一种常规检查，推广应用。

关键词: 肺泡蛋白沉积症, 容积数据高分辨率CT, 诊断