OBJECTIVE: Central linear densities are often seen at the level of the diaphragm on CT scans of the chest. To determine the cause of these densities, we evaluated helical CT scans and correlated the results with the findings from a study of cadavers. SUBJECTS AND METHODS: Forty patients who had normal findings on conventional CT scans had helical CT of the entire chest. For the cadaveric study, we examined the lung bases and extrapleural spaces on the diaphragmatic surface in 22 formalinized cadavers. RESULTS: On helical CT scans, linear densities extending laterally from the mid-part of the right side of the inferior vena cava and from the posterior margin of the left ventricle were seen on the right side of the chest in 12 subjects (30%) and on the left side in 17 subjects (42%). In the cadavers, the inferior phrenic artery and the accompanying vein ran over the diaphragmatic dome in the extrapleural space from the region of the inferior vena cava on the right and from the posterior margin of the left ventricle on the left. These supradiaphragmatic vessels were seen on the right side in 10 cadavers (45%) and on the left side in four cadavers (18%). CONCLUSION: We conclude that these linear densities at the level of the diaphragm on CT scans of the chest represent the inferior phrenic artery and vein.
OBJECTIVE: Central linear densities are often seen at the level of the diaphragm on CT scans of the chest. To determine the cause of these densities, we evaluated helical CT scans and correlated the results with the findings from a study of cadavers. SUBJECTS AND METHODS: Forty patients who had normal findings on conventional CT scans had helical CT of the entire chest. For the cadaveric study, we examined the lung bases and extrapleural spaces on the diaphragmatic surface in 22 formalinized cadavers. RESULTS: On helical CT scans, linear densities extending laterally from the mid-part of the right side of the inferior vena cava and from the posterior margin of the left ventricle were seen on the right side of the chest in 12 subjects (30%) and on the left side in 17 subjects (42%). In the cadavers, the inferior phrenic artery and the accompanying vein ran over the diaphragmatic dome in the extrapleural space from the region of the inferior vena cava on the right and from the posterior margin of the left ventricle on the left. These supradiaphragmatic vessels were seen on the right side in 10 cadavers (45%) and on the left side in four cadavers (18%). CONCLUSION: We conclude that these linear densities at the level of the diaphragm on CT scans of the chest represent the inferior phrenic artery and vein.