Pleural Disease In this segment we are going to be talking about a variety of pleural conditions that can be evaluated with imaging.

Pleural Disease Air in the pleural cavity Pneumothorax: from airway or from atmosphere Let’s talk first about various pleural diseases. I include in pleural diseases air within the pleural cavity. Remember that normally the pleural cavity is a potential space between the visceral and parietal pleural. Once that’s space is violated and air has entered that space, whether from the airway or from the atmosphere the condition debris would be referred to as a pneumothorax.

Pneumothorax Air in the pleural space Expiratory view and lateral decubitus view (affected side up) are best for evaluation Commonly due to rupture of blebs or bullae (emphysema) of the lung or direct trauma (rib fractures, knife or bullet wounds) Pneumothorax or air within the pleural space can be best seen with the utilization of an expiratory view having the patient exhale and taking a frontal radiograph, or a lateral decubitus view with the individual lying on their side. If the affected side is up, the lung will fall away from the chest wall and will allow the best evaluation of the pneumothorax. Causes of pneumothorax can include; the rupture of a bleb or bulla in the case of a patient with emphysema. It could be as a result of trauma as a result of a rib fracture as might occur with an injury or could also be caused by penetrating injury such as knife or bullet wounds.

Pneumothorax X-ray signs: Lucent area with no lung markings located laterally or at the apex of thoracic cavity (if the amount of air is small) The border of collapsed lung is seen as a sharp line (visceral pleura) Some of the radiographic signs of a pneumothorax that we will look for include the presence of a lucent area with no lung markings typically at the lateral aspect or the apex of the thoracic cavity. At the apex especially when the amount of air within the pleural space is small. The border of the collapsed lung will be seen as a sharp line, this sharp line representing the visceral pleura.

Bilateral Pneumothoraces PA film inspiration Lucent area adjacent to lateral chest walls (arrows) No lung vessels seen (beyond visceral pleura) Pleural border of collapsed lungs vaguely seen Let’s next look at a couple of examples. Here is an individual with bilateral pneumothoraces. The arrows indicate the presence of the margins of the visceral pleura. Peripheral to the sharp line demarcating the visceral pleural from the air within the chest cavity, we see no lung markings as a result of the collapse or separation of the lung from the chest wall. There are no vessels identified in this area because are all contained within the lung parenchyma itself. The pleural border of the collapse lungs is vaguely seen.

Bilateral Pneumothoraces Expiration PA film Pneumothoraces appear larger because lung volume is decreased while pleural volume is unchanged If we have the patient exhale and we do an expiration film we’ll see that the pneumothoraces appear larger, because the overall volume of the lungs has decreased while there has been no change in the volume of the air within the pleural cavity; thus, an apparent increase in size of the non-lung containing thorax.

Massive Left Pneumothorax PA chest Very large left pneumothorax Left chest lucent Collapsed left lung, opaque area at the left hilum Mediastinum normal (no shift) In another individual who has a massive left pneumothorax on the PA chest film we see that the pneumothorax has led to almost total collapse of the left lung. Note that there is no shift of the midline structures to the right and there does not appear to be significant depression of the diaphragm as well. This helps distinguish this pneumothorax from a tension pneumothorax. The lung is collapsed above left hilum and appears opaque. The mediastinum as I mentioned is normal.

Tension Pneumothorax X-ray signs: In tension pneumothorax a ball-valve mechanism will cause increased air pressure which will displace the mediastinum away from the side of the tension pneumothorax and flatten or invert the hemidiaphragm on the side of the pneumothorax Surgical emergency Contrast the findings on the last film with the x-ray signs of a tension pneumothorax. In a tension pneumothorax, a ball-valve-type mechanism cause’s increased air pressure within the hemi-thorax that is involved, ultimately leading to displacement of the mediastinum away from the tension pneumothorax and flattening or inversion of the diaphragm on the side of the pneumothorax. This is a surgical emergency, because a rapid decompression is necessary. The effect of the tension pushing on the mediastinum ultimately leads to impairment of venous return to the heart and subsequent death.

Tension Pneumothorax Lucent periphery Pleural margin Inverted diaphragm Shift of midline to the left Atelectasis / loss of volume on left Here, in an image we identify a tension pneumothorax on the right side. Note the peripheral lucency with a pleural margin, the visceral pleural margin being identified. Note that the diaphragm has been inverted and also note that this there is a shift of the midline structures to the left. The impact of the shift in midline structures has caused an atelectasis or volume loss on the left side. The impact on the mediastinum will lead to impaired venous return to the heart.