Anatomical structuresdepicted on the lateral chest radiograph have been studied as far back as the mid to late 1900’s (1-9). Bachman et al studied the effect of a mild degree ofrotation on the lateral chest radiograph and the appearance of anatomical structures with slight rotation (1). These studies have given an anatomical basis for radiographic findings on the lateral chest radiograph, but there were limitations in these studies, and more thorough investigation is possible with current advancements in technologies, particularly CT reformat images.
Methods and materials
A CT work station (Siemens Syngo CT workplace) was used to reformat non-contrast chest CT scans to look like a lateral chest radiograph. The width of 500mm was utilised to cover horizontal span across the chest from one lateral end of skin to the other end for reformatting. Left and right posterior arches of the ribs were superimposed to achieve true lateral position. The chest CT was also reformatted to a lateral chest radiograph with minor degrees of obliquity, specifically right anterior oblique and left...
Analysis of the left and right pulmonary arteries show that the right pulmonary artery is positioned slightly anterior and inferior to the left pulmonary artery with slight superimposition on the true lateral position. Therefore, with slight left anterior oblique rotation, the right and left pulmonary arteries are superimposed further and it becomes very difficult to distinguish the two structures. Refer to figure 1for location of left and right pulmonary arteries at true lateral position.
Separation of the left and right pulmonary arteries is...
In conclusion, this paper may help in improving the skills of radiologists in the interpretation of the lateral chest radiograph. It illustrates the radiographic anatomy using CT scan reformat images to mimic a lateral chest radiograph. The effect of minor degrees of obliquity on the visualisation of hilar structures is also demonstrated.
Authors: John HC Shin, Ashu Gupta
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