Condensed images

Condensed images can be used for the follow-up of transport processes such as the mucociliary clearance (clearance of windpipe).
Humidifier and ciliated cells can be found on the windpipe’s wall. Thanks to the wetness, dust motes collided with the windpipe's wall are attached to it. Of course, it would not be practical if the attached motes stayed there. The ciliated cells sweep the motes until the pharynx and after their arrival they go into the stomach. This process is called mucociliary clearance.
Mucociliary clearance can be examined qualitatively by radioactive isotope tracing. The patient is made to breath in radiopharmacon powder. One part of the radiopharmacon is attached inhomogeneously to the windpipe’s wall. The ciliated cells sweep them in the pharynx’s direction together with the dust. A dynamic image sequence is made from the windpipe by a camera.

Figure 39.

 
A ROI is selected at the windpipe. The kth column of the condensed image is created in a way that the value of the pixel at y height equals with the maximum of pixel values at y height inside the kth image’s ROI. Approximately parallel lanes can be observed in the condensed image. The speed of mucociliary clearance is determined from the gradient of the lanes. The y dimension of pixels’ size is mm, the value of it is calculated from the camera’s geometry. The dimension in the direction of x is time (the time used for recording).

The fortune at the examination of windpipe is that its examined section is almost straight, so its projection can be set vertically. However this technique can be used more generally.
Stomach clearance: Patient eats a food traced by radioactive pharmacon and a dynamic exam is conducted.
After the radiopharmacon diffuses inside the stomach, leaves it in smaller portions. Calculating the sum (average or PMax) of images in the sequence the path can be marked where some of the portions quits. The path itself is considered to be ROI. For every ROI point the distance from the initial point on the path is obtained. That pixel value which has y distance from the initial point on the path in the kth image is placed into the kth column of the condensed image at the y height.
The processing and the interpretation of the condensed image are similar to the one above.

Figure 40.