Lu H, Farison J B, Dennis M J
Department of Bioengineering, University of Toledo, OH 43606, USA.
Biomed Sci Instrum. 1997;33:118-25.
In nuclear medicine, the match and mismatch between the images of lung perfusion and ventilation provide an important criterion to diagnose pulmonary embolism. Usually, for imaging clarity, the ventilation scan using 133Xe is performed before the perfusion scan using 99mTc. But the inverse order is preferred clinically, since (i) if the perfusion image is normal, there is no need to do the ventilation scan, and (ii) if the perfusion image is abnormal, the ventilation image can be obtained by focusing on the perfusion abnormalities. However, the quality of the ventilation image is reduced if the ventilation scan is performed after the perfusion scan, because the 140 keV photons emitted from 99mTc will scatter into the acquisition window of 133Xe (81 keV). The purpose of this study is to apply image processing techniques to reduce the scattering effect of 99mTc to get a better 133Xe ventilation image. First, an image sequence in the preferred inverse order is simulated using the images acquired in the normal order. Image processing techniques are used to find an optimized way to reduce the scattering background in the ventilation image. Second, a real image sequence is acquired in the inverse order. An improved ventilation image is then obtained by applying image processing techniques to this image sequence.
在核医学中，肺灌注和通气图像之间的匹配与不匹配为诊断肺栓塞提供了一项重要标准。通常，为了成像清晰，使用133Xe的通气扫描在使用99mTc的灌注扫描之前进行。但临床上更倾向于相反的顺序，原因如下：（i）如果灌注图像正常，则无需进行通气扫描；（ii）如果灌注图像异常，则可以通过关注灌注异常来获取通气图像。然而，如果通气扫描在灌注扫描之后进行，通气图像的质量会降低，因为99mTc发射的140 keV光子会散射到133Xe的采集窗口（81 keV）中。本研究的目的是应用图像处理技术来减少99mTc的散射效应，以获得更好的133Xe通气图像。首先，使用按正常顺序采集的图像模拟出按首选相反顺序的图像序列。利用图像处理技术找到一种优化方法来减少通气图像中的散射背景。其次，按相反顺序采集真实图像序列。然后通过对该图像序列应用图像处理技术获得改进后的通气图像。
