Fig 1.
The method for measuring cardiac cross-sectional area (CSA) is shown. A CT image with the maximum cardiac CSA was initially selected (A). The targeted cardiac area was extracted on the image using a threshold setting (B, from 0 to 300 Hounsfield units) to exclude the pericardial fat pad. Black spots included in the cardiac area are fat tissue or artifacts. The cardiac CSA was measured using another threshold setting (C, from -100 to 300 Hounsfield units) to include the black spots excluded on the former image.
Table 1.
Lung and cardiac measurements on inspiratory and expiratory CT scans (n = 43).
Fig 2.
17-year-old male with bronchiectasis.
Axial and reconstructed coronal CT images at inspiration (A and C) and at expiration (B and D) are shown. The cardiac cross-sectional area and transverse cardiac diameters are smaller at inspiration (A) than at expiration (B). Based on reconstructed coronal images (C, inspiratory; D, expiratory), the diaphragm is dislocated downward during inspiration and the cardiac long axis leans vertically (C) compared with expiration (D). Note that reconstructed coronal images are shown as a reference and were not used for analysis in the study.
Table 2.
Correlations between the E/I ratios of lung and cardiac measurements.
Table 3.
Comparisons of the cardiothoracic ratio (CTR) measured on plain chest film, inspiratory chest CT and expiratory chest CT.
Table 4.
Correlations between CTR measurements.