Smart R C, Lyons N R, Burke J J, Wood C F
Eur J Nucl Med. 1985;11(2-3):65-8. doi: 10.1007/BF00252135.
For several years, radioaerosols have been successfully used to provide detailed images of regional ventilation to aid in the differential diagnosis of pulmonary embolism. It has been widely advocated that the ventilation images should follow the perfusion scan and that the amount of aerosol deposited in the patient's lungs should be three times greater than the perfusion dose. We employed an alternative approach which avoided the deposition of an unpredictable amount of aerosol in individual patients. The aerosol study was performed first, and the activity of the microspheres used for the perfusion images was then tailored to the actual amount of aerosol which the patient had retained. This allowed a microsphere/aerosol activity ratio of 10:1 to be readily achieved, thus successfully masking the ventilation pattern by the perfusion activity. The faster biological clearance of 99mTc-DTPA aerosol from the lung fields, as compared to 99mTc-sulphur-colloid aerosol, allowed higher initial activities to be deposited in the lungs, thus enabling a high-resolution collimator to be used. When the perfusion study was delayed by 1 h (one effective half-life for the 99mTc-DTPA aerosol), it was not necessary to increase the perfusion activity required to mask the ventilation image.
几年来，放射性气溶胶已成功用于提供区域通气的详细图像，以辅助肺栓塞的鉴别诊断。人们普遍主张通气图像应在灌注扫描之后进行，并且沉积在患者肺部的气溶胶量应比灌注剂量大三倍。我们采用了另一种方法，避免了在个体患者中沉积不可预测量的气溶胶。首先进行气溶胶研究，然后根据患者保留的实际气溶胶量调整用于灌注图像的微球活性。这使得微球/气溶胶活性比很容易达到10:1，从而成功地用灌注活性掩盖通气模式。与99mTc-硫胶体气溶胶相比，99mTc-DTPA气溶胶从肺野的生物清除速度更快，这使得可以在肺部沉积更高的初始活性，从而能够使用高分辨率准直器。当灌注研究延迟1小时（99mTc-DTPA气溶胶的一个有效半衰期）时，无需增加掩盖通气图像所需的灌注活性。
