Cardio-thoracic ratio

The cardiothoracic ratio is a simple method for orienting assessment of cardiac size of the people in the radiograph of the chest was added in pa - projection while standing in deep inspiration ( HTQ, also CTR after the English 'cardio - thoracic ratio " ).

Method

For the determination of HTQs the transverse diameter of the heart and the thorax ( chest) measured at the widest point, formed the thorax at the inner edge of the ribs, and the ratio.

Values ​​above 0.5 are considered morbidly and correspond to an enlargement of the heart. The cardiothoracic ratio, however, is non-specific; he says nothing about which parts of the heart are enlarged, and if taken also no conclusion on the cause. Moreover, the value, for example by abnormalities of the chest like a barrel - chest or a spinal curvature (scoliosis ) is affected.

In X-ray images of the lungs when lying down, it is not useful to determine the cardiothoracic ratio with this method, since these rays are taken usually in the anteroposterior projection. Due to the beam path, the heart appears to be larger in the picture. In addition, the deep inspiration is in bedridden patients often not possible, which leads to a compression of the thoracic organs. The heart is in this case represented wider.

In an alternative method for determining the cardio-thoracic ratio, the extent of the center line to the right or to the left is measured at the respective widest point and added in place of the cross diameter of the entire heart, the transverse diameter of the thorax at the level of the right diaphragm dome determined.