PROJECT FOR DEVELOPMENT OF HIGH-RESOLUTION MR IMAGING OF DIFFUSE LUNG DISEASES

本研究旨在探讨磁共振成像在弥漫性肺部疾病诊断中的应用价值。在初步研究中，我们获得了包括正常肺和急性间质性肺炎在内的人肺标本的MR图像，以评估在排除呼吸运动的情况下MR成像的能力。虽然正常充气固定肺的图像不能显示肺的细微结构，但在T1加权像上，急性间质性肺炎的肺标本可见肺小叶内不均匀的纤维化改变和细支气管扩张。然而，在临床环境中，MRI图像的视场很小，切片很薄，质量很差，很难应用于临床检查。快速梯度回波图像显示肺小叶内的血管结构，呼吸门控快速自旋回波图像显示肺纤维化中的小囊性改变，视野较大，切片较厚。然而，在评价弥漫性肺部疾病的形态变化方面，并没有获得比高分辨率CT更多的信息。此外，病变的信号强度是非特异性的，因此在鉴别诊断中没有额外的信息。目前，由于呼吸运动、磁化率伪影和低质子密度，高质量的MR图像很难获得。快速磁共振成像技术的显著进步为临床应用MR成像评估弥漫性肺部疾病提供了高质量的肺实质图像。

This study was performed to assess the possibility of MR imaging in the evaluation of diffuse pulmonary diseases. In the preliminary study, we obtained MR images of the human lung specimen, including normal lung and acute interstitial pneumonia, to evaluate the capability of MR imaging when the respiratory motion was excluded. Although the image of normal inflated and fixed lung could not reveal the fine structures of the lung, uneven fibrotic change and bronchiolar dilatation within the pulmonary lobule was demonstrated in the lung specimen of acute interstitial pneumonia on T1-weighted images. However, in a clinical setting, MR images with very small FOV and thin-section was poor in quality so that it was difficult to apply the clinical examination. With relatively large FOV and thick sections, fast gradient-echo images demonstrated vascular structures within the pulmonary lobule and respiratory-gated fast spin-echo images showed small cystic changes in pulmonary fibrosis. However, no more information than high-resolution CT was obtained in the evaluation of morphological changes of diffuse lung diseases. In addition, signal intensity of the lesion was non-specific so that there was no additional information in the differential diagnosis. At the present time, high-quality MR images are difficult to obtain because of respiratory motion, susceptibility artifact, and low proton density. Marked advance of fast MR imaging technique providing high-quality images of the lung parenchyma is necessary to clinically apply MR imaging to the evaluation of diffuse lung diseases.