Variation in the thickness of the diaphragmatic crura with respiration.

Misinterpretation of the diaphragmatic crura on axial computed tomography images is a recognized pitfall in diagnosis. The right diaphragmatic crus is generally longer and thicker than the left. The authors observed a case in which the left crus was thicker than the right, causing diagnostic difficulty. Obtaining scans at full expiration and full inspiration clarified the situation. Confirmation of respiratory variation in crural thickness was obtained in ten patients. The crura increased in thickness on inspiration, compared with the size on expiration.