Mediastinal shift

{{Main|Pneumothorax#Tension_pneumothorax}}

Tension pneumothorax is an emergent condition in which air gets trapped in the space between the chest wall and the lung. This space is referred to as the pleural space. Because air can't escape from this space, the air pocket grows larger and larger, resulting in the lung collapse closest to the pneumothorax. Forces are transmitted to the mediastinum and effectively "push" the mediastinal structures to the opposite side of the chest.{{Citation |last1=Jalota Sahota |first1=Ruchi |title=Tension Pneumothorax |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK559090/ |access-date=2024-02-21 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32644516 |last2=Sayad |first2=Edouard}}

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{{Main|Pleural effusion}}

File:Pleural effusion - Left lung (7471755836).jpg

A pleural effusion is an accumulation of fluid inside the pleural space. If this collection of fluid gets large enough, it can also push structures in the chest away from it and cause a mediastinal shift. However, a pleural effusion can also pull the mediastinal structure towards itself. If this is the case, then there is an underlying condition causing the collapse of the lung on that side. An example is a tumor obstructing a bronchus and causing lung collapse and pleural effusion.

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{{Main|Hemothorax}}

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Hemothorax, or accumulation of blood in the pleural space, can result from trauma or surgical procedures in the chest. This accumulation of blood can grow large enough to compress the lung and push away other structures in the chest, thus causing a mediastinal shift.{{Citation |last1=Taghavi |first1=Sharven |title=Mediastinal Trauma |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK526031/ |access-date=2024-03-06 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30252287 |last2=Askari |first2=Reza}} On a chest x-ray, a hemothorax can appear similarly to a pleural effusion with blunting of the pleural recess and white out of normal lung zones.{{Cite journal |last1=Salim |first1=Shihas |last2=Ganeshram |first2=Prasanthi |last3=Patel |first3=Amish Dilip |last4=Kumar |first4=Anita A. |last5=Vemuri |first5=Divya |last6=Jeyachandran |first6=Vijay |last7=Rajamanickam |first7=Deepan |last8=Shantha |first8=Ghanshyam Palamaner Subash |date=2008-10-07 |title=Unilateral hemothorax in a 46 year old South Indian male due to a giant arteriovenous hemodialysis fistula: a case report |journal=Cases Journal |volume=1 |issue=1 |pages=225 |doi=10.1186/1757-1626-1-225 |doi-access=free |issn=1757-1626 |pmc=2567296 |pmid=18840271}} In the setting of traumatic chest injury, rib fractures are also commonly observed on x-ray.{{Cite journal |last1=Kim |first1=Michelle |last2=Moore |first2=James E. |date=2020 |title=Chest Trauma: Current Recommendations for Rib Fractures, Pneumothorax, and Other Injuries |journal=Current Anesthesiology Reports |volume=10 |issue=1 |pages=61–68 |doi=10.1007/s40140-020-00374-w |issn=1523-3855 |pmc=7223697 |pmid=32435162}}

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{{Main|Empyema}}

File:Radiology 2706 1407 empyema progression nevit.gif progression seen on the left side of the chest over the course of 2 weeks.]]

An empyema is a collection of pus inside the pleural cavity. It is a complication of pneumonia or thoracic injury or surgery and also requires urgent diagnosis and treatment.{{Cite journal |last1=Feller-Kopman |first1=David |last2=Light |first2=Richard |date=2018-02-22 |title=Pleural Disease |url=https://pubmed.ncbi.nlm.nih.gov/29466146/ |journal=The New England Journal of Medicine |volume=378 |issue=8 |pages=740–751 |doi=10.1056/NEJMra1403503 |issn=1533-4406 |pmid=29466146}} Radiographic appearance is similar to that of a pleural effusion with costophrenic angle blunting and white out of lung zones. CT imaging is necessary to evaluate the structure of the empyema and evaluate for loculation or separation of the pus into different compartments.{{Citation |last1=Garvia |first1=Veronica |title=Empyema |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK459237/ |access-date=2024-03-06 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29083780 |last2=Paul |first2=Manju}} Finally, ultrasound is becoming a more commonly used imaging technique to evaluate an empyema. Ultrasound is more readily available at the bedside, is better at detecting pleural effusion, and can be used to guide thoracentesis to remove the empyema.{{Cite journal |last1=Ohara |first1=Gen |last2=Iguchi |first2=Kesato |last3=Satoh |first3=Hiroaki |date=2018-10-19 |title=VATS and Intrapleural Fibrinolytic Therapy for Parapneumonic Empyema |journal=Annals of Thoracic and Cardiovascular Surgery|volume=24 |issue=5 |pages=263–264 |doi=10.5761/atcs.lte.18-00092 |issn=2186-1005 |pmc=6198002 |pmid=29962389}}

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File:Pleural based thymoma - CT scan - Case 282 (12074545993).jpg

Masses such as tumors can also cause compression and displacement of mediastinal structures. There are various mediastinal tumors, and they are classified by their location in the chest. Notable examples include germ cell tumors and lymphomas.{{Cite journal |last1=Ghigna |first1=Maria-Rosa |last2=Montpreville |first2=Vincent Thomas de |date=2021-12-31 |title=Mediastinal tumours and pseudo-tumours: a comprehensive review with emphasis on multidisciplinary approach |url=https://err.ersjournals.com/content/30/162/200309 |journal=European Respiratory Review |language=en |volume=30 |issue=162 |doi=10.1183/16000617.0309-2020 |issn=0905-9180 |pmc=9488622 |pmid=34615701}} Teratomas are a class of germ cell tumors that arise in the chest due to failure of germ cell migration during development. They can expand to large sizes and cause hemoptysis and pleural effusion. Radiographic features of teratomas typically include fluid and fat but also muscle, teeth, and bones inside the mass.{{Citation |last1=Jilani |first1=Talha N. |title=Mediastinal Cancer |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK513231/ |access-date=2024-03-06 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30020603 |last2=Killeen |first2=Robert B. |last3=Siddiqui |first3=Abdul H.}}

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{{Main|Atelectasis}}

File:Atelectasia1.jpg

Atelectasis is the partial collapse of a lung that is reversible. There are numerous etiologies, including post-operative atelectasis, surfactant deficiency, mucus plugging, and foreign body aspiration. Notably, post-operative atelectasis is thought to be caused by general anesthesia administration. Collapse of the affected lung shifts mediastinal structure towards the same side and can be observed on chest x-ray or CT. Radiographic features include increased opacification of collapsed lung and/or tracheal shift.{{Citation |last1=Grott |first1=Kelly |title=Atelectasis |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK545316/ |access-date=2024-03-07 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31424900 |last2=Chauhan |first2=Shaylika |last3=Dunlap |first3=Julie D.}}

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{{Main|Pulmonary hypoplasia}}

Fetal conditions can also cause a mediastinal shift during development. For example, pulmonary hypoplasia is the underdevelopment of a lung due to various etiologies. These include agenesis due to gene mutation, fetal hydrothorax, and congenital diaphragmatic hernia. These conditions lead to incomplete development of lung tissue or hypoplasia. This can be unilateral or bilateral and is seen on x-ray as a mediastinal shift towards the side of the underdeveloped lung.{{Cite journal |last1=Cao |first1=Li |last2=Du |first2=Yan |last3=Wang |first3=Ling |date=2017 |title=Fetal pleural effusion and Down syndrome |journal=Intractable & Rare Diseases Research |volume=6 |issue=3 |pages=158–162 |doi=10.5582/irdr.2017.01028 |issn=2186-3644 |pmc=5608924 |pmid=28944136}}{{Citation |last1=Tisekar |first1=Owais R. |title=Hypoplastic Lung Disease |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK562139/ |access-date=2024-03-07 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32965810 |last2=Ak |first2=Ajith Kumar}} Additionally, mediastinal shifts can also be detected using antenatal ultrasonography.{{Cite journal |last1=Colombani |first1=M. |last2=Rubesova |first2=E. |last3=Potier |first3=A. |last4=Quarello |first4=E. |last5=Barth |first5=R. A. |last6=Devred |first6=P. |last7=Petit |first7=P. |last8=Gorincour |first8=G. |date=2011 |title=[Management of fetal mediastinal shift: a practical approach] |url=https://pubmed.ncbi.nlm.nih.gov/21352743 |journal=Journal de Radiologie |volume=92 |issue=2 |pages=118–124 |doi=10.1016/j.jradio.2010.12.002 |issn=1773-0384 |pmid=21352743}}

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{{Main|Pectus excavatum}}

File:Trichterbrust im Roentgenbild des Thorax pa.jpg

File:Pectusexcavatum.png

This condition is often called "funnel chest" and is observed as depression of the anterior chest at the xiphisternum. Pectus excavatum is commonly unilateral and, therefore, can lead to asymmetric distribution of thoracic organs. Therefore, a mediastinal shift can be seen in severe cases. Radiographic features include a leftward deviation of the heart and deformed third to seventh ribs. Patients often present with exercise tolerance, cardiac arrhythmias, and heart murmur.{{Citation |last1=Sharma |first1=Girish |title=Pectus Excavatum |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK430918/ |access-date=2024-03-07 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=28613668 |last2=Carter |first2=Yvonne M.}}

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File:PneumonectomyXray.PNG

A pneumonectomy is a surgical procedure in which an entire lung is removed. A common reason for performing this procedure is for lung cancer originating in the lung itself.{{Citation |last1=Beshara |first1=Michael |title=Pneumonectomy |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK555969/ |access-date=2024-03-10 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32310429 |last2=Bora |first2=Vaibhav}} This leads to a mediastinal shift towards the empty side of the thorax. Notably, patients can experience post pneumonectomy syndrome due to a severe mediastinal shift. This presents as difficulty breathing due to a shift of airways and rotation of the heart and great vessels. On x-ray, white out of the operated side and hyperinflation of the remaining lung is often observed.{{Cite journal |last1=de Groot |first1=Patricia M. |last2=Truong |first2=Mylene T. |last3=Godoy |first3=Myrna C. B. |date=2018 |title=Postoperative Imaging and Complications in Resection of Lung Cancer |url=https://pubmed.ncbi.nlm.nih.gov/29807639 |journal=Seminars in Ultrasound, CT, and MR |volume=39 |issue=3 |pages=289–296 |doi=10.1053/j.sult.2018.02.008 |issn=1558-5034 |pmid=29807639|s2cid=44142767 }}

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{{Main|Foreign body aspiration}}

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Foreign body aspiration is a major cause of death in young children due to their underdeveloped swallowing coordination. Young children most commonly ingest toys, coins, or food.{{Citation |last1=Rose |first1=David |title=Airway Foreign Bodies |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK539756/ |access-date=2024-03-20 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30969578 |last2=Dubensky |first2=Laurence}} On chest x-ray, the most frequent sign is air trapping that can lead to a mediastinal shift. Atelectasis and pneumothorax may also occur in the setting of foreign body aspiration. The diagnosis is made in conjunction with clinical symptoms and confirmed and treated with bronchoscopy.{{Citation |last1=Cramer |first1=Natan |title=Foreign Body Aspiration |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK531480/ |access-date=2024-03-20 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30285375 |last2=Jabbour |first2=Noel |last3=Tavarez |first3=Melissa M. |last4=Taylor |first4=Roger S.}}

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File:Bullus emphasemaCT.png

Bullous emphysema is a condition seen in patients with chronic obstructive pulmonary disease (COPD). The units making up the substructure of the lung (alveoli) become permanently enlarged due to the destruction of their walls. This leads to hyperinflation of the alveoli and, thus, the lungs. When this occurs asymmetrically, one lung can be larger than the other.{{Citation |last1=Siddiqui |first1=Najam A. |title=Bullous Emphysema |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK537243/ |access-date=2024-03-20 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30725928 |last2=Mansour |first2=Mohamed K. |last3=Nookala |first3=Vinod}} A severe variant of this condition is called giant bullous emphysema. On chest x-ray, one lung will be significantly more inflated than the other, causing a mediastinal shift. Bullous emphysema's radiographic appearance on x-ray mimics a tension pneumothorax. This presents a medical challenge as these diseases are treated differently despite appearing similarly on x-ray.{{Cite journal |last1=Ascano |first1=Maria Patricia |last2=Kramer |first2=Nicholas |last3=Le |first3=Khoa |last4=Ascano |first4=Maria Patricia |last5=Kramer |first5=Nicholas |last6=Le |first6=Khoa |date=2024-03-11 |title=Differentiating Giant Bullous Emphysema From Tension Pneumothorax: A Case Report |journal=Cureus |language=en |volume=16 |issue=3 |pages=e55988 |doi=10.7759/cureus.55988 |issn=2168-8184|doi-access=free |pmid=38606232 |pmc=11007189 }}{{Cite journal |last1=Samanta |first1=Rudra P. |last2=Agarwal |first2=Srikant |last3=Sengupta |first3=Susmita |last4=Samanta |first4=Rudra P. |last5=Agarwal |first5=Srikant |last6=Sengupta |first6=Susmita |date=2022-11-07 |title=Giant Bullous Emphysema Mimicking Spontaneous Pneumothorax |journal=Cureus |language=en |volume=14 |issue=11 |pages=e31182 |doi=10.7759/cureus.31182 |doi-access=free |pmid=36505170 |issn=2168-8184|pmc=9727579 }}

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{{Main|Congenital pulmonary airway malformation}}

File:Zystisch adenomatoide Malformation bei Neugeborenem-Roe.jpg

Congenital pulmonary airway malformation (CPAM) is a rare disease in which the lung airways develop abnormally in the fetus. This leads to infants having pockets of air and cystic masses in their lungs. These can expand in size and cause a mediastinal shift, especially in the higher grades of CPAM. Diagnosis is usually made on ultrasound and supplemented with x-ray, CT, or MRI to further define the malformation. On chest x-ray, CPAM has varying appearances but may look like "bubbles" within the lung fields.{{Citation |last1=Mehta |first1=Pooja A. |title=Congenital Pulmonary Airway Malformation |date=2024 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK551664/ |access-date=2024-03-20 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31869128 |last2=Sharma |first2=Girish}}

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{{Radiologic signs}}

Category:Radiologic signs