A chest radiograph ordered to evaluate for lung metastasis revealed cardiomegaly, a sclerotic aortic knob
, and a mass-like abnormality of unknown etiology in the right paratracheal region (Fig.
48, with calcification of aortic knob
and normal lung aspect (Figure 2).
On the other hand there is paucity of data regarding the size of the aortic knob (AK) in Indian population which can be easily visualized in the Postero-Anterior Chest X-ray which is the commonest imaging modality in both rural and urban areas of India and economically feasible as it is cheaper than any other imaging modalities like CT scan or MRI, though the latter techniques are better indicators in assessing cardiac conditions than the chest X-ray.
Aortic knob is the radiographic not an anatomic entity.
The foreshortened distal most portion of the aortic arch where it joins the descending aorta represents the aortic knob or aortic knuckle and it constitutes the superior most part of the left border of the cardiac silhouette.
The aortic knob is a radiographic structure that is formed by the foreshortened aortic arch and a portion of the descending aorta.
The widest point of the ascending aortic knob was measured along the horizontal line from the point of the lateral edge of the trachea to the left lateral wall of the aortic knob (Fig.
The initial diagnostic test is on-table AP chest radiography (CXR), which may show a widening of the mediastinum, the most common finding (> 90% of cases), and blunting of the aortic knob
, seen in 19.
We included a photo of a clavicle insertion in which the blade, held in a reverse grip, is plunged behind the opponent's collar bone, on the left side of the chest, and shoved down so that the blade ruptures the aortic knob
CXR: Marked cardiomegaly in chronic AR with dilatation of the aortic knob