Copyright © 2009 [Gerald R. Aben, MD MSU Department of Radiology]. All rights reserved.
Revised: April 08, 2009
Step-by-Step Approach


Evaluating the Chest Radiograph

Step 5:   The Diaphragms

Evaluation of the diaphragms is fairly straight forward.  In the normal patient, on the frontal exam, the diaphragms are gently curving with a convexity directed cephalad.   The entire right diaphragm and in most cases the entire left diaphragm are visible.   Depending on patient positioning for the frontal exam, occasionally the medial portions of the left diaphragm may be poorly seen due to the presence of the heart above.  


Unlabeled frontal.  

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Labeled frontal, white lines represent the visualized right and left diaphragms


On the lateral view, the entire right diaphragm and the posterior two thirds of the left diaphragm should be visible.  It is possible to differentiate the two sides of the diaphragm on the lateral by observing the height of the diaphragm, the right usually higher, and the absence of diaphragm visualization on the left due to the presence of the heart anteriorly.


Normal lateral diaphragms.  Note the undulation that can normally be seen along each diaphragm

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The upper arrows represent the right diaphragm.  The lower arrows the left.  The anterior-most portion of the left diaphragm is not seen.


The costo phrenic angles in the normal healthy patient will be sharp and come to a fairly distinct point.  This is true both in the frontal and lateral projections.   A caution is offered however, in patients with extremely deep inspirations, the angles may be somewhat 'blunted' yet still be normal.

White arrows indicate the normal costo phrenic angles in this woman
The right angle is sharp, the left costo phrenic angle is slightly blunted in this woman.
(upper arrow)


The levels of the diaphragms in normal patients will show some variation.  The right diaphragm is usually slightly higher than the left.  If this is switched, this may be a sign of pathology involving the left diaphragm.  Marked asymmetry with the right diaphragm being high could represent evidence for a paralyzed right diaphragm or the presence of hepatomegaly.

The right diaphragm is higher in this patient.
The diaphragms are close to equal in level in this patient.


Normally, there should be no air collections directly below the right diaphragm.  A crescent of air beneath the right diaphragm may represent free intraperitoneal air (pneumoperitoneum), or an unusual interposition of the colon between the liver and diaphragm.  Remember that colonic is usually a larger collection.  Haustra will be seen in colon interposed between the diaphragm and the liver.


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Arrows from above indicate the diaphragm.  Arrowheads from below the top of the liver.  Dark area between is free air in the peritoneal cavity.


A loss of the sharply defined contour of the diaphragm represents the presence of an abnormality of the adjacent lung.  This could represent pneumonia, or possibly a neoplasm.

The lateral right diaphragm is obscured (lower black arrows) by a right lower lobe pneumonia (upper arrows)
The lateral projection demonstrates the RLL pneumonia between the arrows.