Study Smarter
This patient has a moderate-sized right pleural effusion. The lateral decubitus film places the effusion in the dependent position and will show layering unless the effusion is loculated. This is noted in the same patient’s left lateral decubitus film.
Normal PA film of a male. Note the right and left clavicles (cl), posterior (p1-4) and anterior (a1-2) ribs, right and left costophrenic angles(cpa), right cardiophrenic angles (cdpa), right and left hemidiaphragms (hd), gastric air bubble (gab), trachea (tr), right and left mainstem bronchi (br), mediastinal shadow (med), carina (ca), and right and left hila (hi). The normal position of the minor fissure (mi) is also indicated.
Normal PA film of a male. Note the right and left clavicles (cl), posterior (p1-4) and anterior (a1-2) ribs, right and left costophrenic angles(cpa), right cardiophrenic angles (cdpa), right and left hemidiaphragms (hd), gastric air bubble (gab), trachea (tr), right and left mainstem bronchi (br), mediastinal shadow (med), carina (ca), and right and left hila (hi). The normal position of the minor fissure (mi) is also indicated.
Because the AP projection positions the heart and mediastinum further from the x-ray film than the PA projection, these structures appear magnified with the AP view. Other clues that you are looking at an AP projection include clavicles that project above the lung apices and scapulae that project over the lung fields.
Nipple shadows can often mimic pulmonary nodules. Clues to nipples being the source of the apparent nodules on the lateral radiograph, bilaterally and “lesions” whose inferior and lateral borders appear sharper than their superior and medial margins. Confirmation can be obtained by repeating the study with nipple markers or obtaining a different projection.
Components of the PA mediastianl shadow (A) include SVC (1), ascending aorta (2), RA (3), IVC (4), aortic arch (5), pulmonary trunk (6), LA appendage (7), and LV (8).
Mediastinal compartments on the lateral film (B) include: superior (S), anterior (A), middle (M) and posterior (P) compartments.
This is a normal lateral film of a female patient. Note the spine (sp), anterior costophrenic angle (acpa), gastric air bubble (gab), trachea (tr), left mainstem bronchus (lbr), right mainstem bronchus (rbr), aortic arch (ao), anterior/retrosternal (acs) and posterior/retrocardiac (pcs) clear spaces, and breast shadow (m)
On a film taken in full inspiration, the right hemidiaphragm should project over the 6th anterior interspace or 10th rib posteriorly. Films taken without a full inspiration are described as having a “poor inspiratory result”. This may result from a poor inspiratory effort or any other condition that prevents full inspiration.
This patient’s chest x-ray is normal in full inspiration. In relative expiration, the cardiac silhouette appears enlarged and the pulmonary vasculature appears crowded and indistinct. This appearance is easily mistaken for pulmonary edema
Hypertrophic First Rib
Rib hypertrophy, often at the costochondral junction and particularly involving the first rib, commonly mimics a lung nodule on the PA projection. It has been called “the medical student’s tumor.” Clues that the “nodule” is in fact due to rib hypertrophy include its absence on the lateral view, bilaterality, and the presence of rib hypertrophy at other levels. If there is any doubt, a lordotic projection can be obtained.
This patient has a well circumscribed mass in the posterior mediastinum. The valve of the lateral view is well depicted in this case; on the frontal radiograph there is no way to localize the lesion. The differential diagnosis for a posterior mediastinal mass includes:
This mass proved to be a neurofibroma.
