Significance of high-resolution CT findings by using densitometry in patient with pulmonary alveolar proteinosis.

本研究的目的是通过高分辨率CT密度测量分析肺泡蛋白沉积症（PAP）患者磨玻璃影（GGO）的肺部衰减。本研究纳入了5例病例。进行吸气式薄层螺旋胸部CT扫描（Aquilion 64, Toshiba medical systems, Japan）。在不同严重程度的PAP病例中，平均肺衰减和全肺体积有所不同。根据直方图特征，与PAP相关的比值（定义为GGO的CT肺体积除以CT总肺体积的比值）有助于区分PAP病变与正常区域。GGO密度在-850 ~ -750 HU范围内提示PAP在HRCT上的病变，在此范围内肺体积与血清KL-6 （r=0.867）和CEA （r=0.616）的相关性最大。虽然早期诊断PAP非常困难，但这些结果可能是PAP诊断程序的实用影像学表现。

The aim of this study was to analyze the lung attenuation of ground glass opacity (GGO) by using densitometry on high-resolution CT in patients with pulmonary alveolar proteinosis (PAP). Five cases were enrolled in this study. Inspiratory thin-slice spiral chest CT scans (Aquilion 64, Toshiba medical systems, Japan) were performed. The mean lung attenuation and whole lung volume varied in each severity of PAP cases. According to the histogram feature, the ratio associated with PAP (defined as the ratio of CT lung volume for GGO divided by total CT lung volume) contributed to differentiate PAP lesion from normal area. GGO for the range of density -850 to -750 HU suggested the lesion of PAP on HRCT and the lung volume in this range showed the greatest degree correlation with the levels of serum KL-6 (r=0.867)and CEA (r=0.616). Although it is very difficult to early diagnose as PAP in generally, these results might be practical radiographic findings of diagnostic procedure for PAP.