Heart-thorax quotient

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Scheme for determining the heart-thorax quotient (common method): HTQ = H / Th. (H: transverse diameter of the heart; Th: transverse diameter of the thorax, measured on the inner edge of the rib at the widest point)
Scheme for determining the heart-thorax quotient (alternative method): HTQ = (H re + H li) / Th (H re: transverse diameter of the heart measured from the center line to the right, H li: transverse diameter of the heart from the center line to the left measured; Th: transverse diameter of the thorax, measured at the inner edge of the rib at the level of the right diaphragmatic crest)

The heart-thorax quotient (HTQ, also CTR from the English " cardio-thoracic ratio ") is a simple method for the orientational assessment of the size of the heart in the chest x-ray , recorded in pa-projection while standing in deep inspiration . In veterinary medicine, the size of the heart is mostly assessed using the Vertebral Heart Score .

method

To determine the HTQ, the transverse diameter of the heart and that of the thorax (chest) are measured at the widest point, and for the thorax at the inner edge of the ribs, and the ratio is calculated.

Values ​​above 0.5 are considered pathological and correspond to an enlargement of the heart . The heart-thorax quotient, however, is unspecific; it says nothing about which parts of the heart are enlarged and does not allow any conclusions to be drawn about the cause. In addition, the value z. B. influenced by anomalies of the chest such as a barrel thorax or a curvature of the spine (scoliosis).

For x-ray images of the lungs while lying down , it does not make sense to determine the heart-thorax quotient with this method, since these images are usually made in ap projection. Because of the beam path, the heart appears larger in the image. In addition, deep inspiration is often not possible in bedridden patients, which leads to a compression of the thoracic organs. The heart is shown wider.

In an alternative method for determining the heart-thorax quotient, instead of the transverse diameter of the entire heart, the extent from the center line to the right or left is measured at the widest point in each case and added, the transverse diameter of the thorax is at the level of the right diaphragm certainly.

literature

  • E. Bücheler, K.-J. Lackner, M. Thelen: Introduction to Radiology. 11th edition, Georg Thieme, 2006, ISBN 3-13-316011-7 , p. 345.

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