Cardiothoracic ratio

Changed by Pariya Zamanzadeh, 28 Jun 2018

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The cardiothoracic ratio (CTR) aids in the detection of enlargement of the cardiac silhouette, which is most commonly from cardiomegaly but can be due to other processes such as a pericardial effusion

Terminology

Some report CTR as a percentage, however this is incorrect, as it is a ratio.

Radiographic features

The CTR is measured on a PA chest x-ray, and is the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura). A normal measurement should be ≤0less than 0.5.

Related pathology

It should be noted that this measurement is a crude marker of disease 4. If the patient is symptomatic then echocardiography is required but the yield of echocardiography is low if performed just for an increased CTR 3.

In the following situations, cardiothoracic ratio is more than 0.5 on a PA chest radiograph, but heart and pericardium are normal:

  • -<p>The <strong>cardiothoracic ratio</strong> (<strong>CTR</strong>) aids in the detection of <a href="/articles/enlargement-of-the-cardiac-silhouette">enlargement of the cardiac silhouette</a>, which is most commonly from <a href="/articles/cardiomegaly">cardiomegaly</a> but can be due to other processes such as a <a href="/articles/pericardial-effusion">pericardial effusion</a>. </p><h4>Terminology</h4><p>Some report CTR as a percentage, however this is incorrect, as it is a ratio.</p><h4>Radiographic features</h4><p>The CTR is measured on a PA <a href="/articles/chest-radiograph">chest x-ray</a>, and is the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura). A normal measurement should be ≤0.5.</p><h4>Related pathology</h4><p>It should be noted that this measurement is a crude marker of disease <sup>4</sup>. If the patient is symptomatic then echocardiography is required but the yield of echocardiography is low if performed just for an increased CTR <sup>3</sup>.</p><p>In the following situations, cardiothoracic ratio is more than 0.5 on a PA chest radiograph, but heart and pericardium are normal:</p><ul>
  • +<p>The <strong>cardiothoracic ratio</strong> (<strong>CTR</strong>) aids in the detection of <a href="/articles/enlargement-of-the-cardiac-silhouette">enlargement of the cardiac silhouette</a>, which is most commonly from <a href="/articles/cardiomegaly">cardiomegaly</a> but can be due to other processes such as a <a href="/articles/pericardial-effusion">pericardial effusion</a>. </p><h4>Terminology</h4><p>Some report CTR as a percentage, however this is incorrect, as it is a ratio.</p><h4>Radiographic features</h4><p>The CTR is measured on a PA <a href="/articles/chest-radiograph">chest x-ray</a>, and is the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura). A normal measurement should be less than 0.5.</p><h4>Related pathology</h4><p>It should be noted that this measurement is a crude marker of disease <sup>4</sup>. If the patient is symptomatic then echocardiography is required but the yield of echocardiography is low if performed just for an increased CTR <sup>3</sup>.</p><p>In the following situations, cardiothoracic ratio is more than 0.5 on a PA chest radiograph, but heart and pericardium are normal:</p><ul>

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