Imaging of thoracic hernias: types and complications

Abstract

Thoracic hernias are characterised by either protrusion of the thoracic contents outside their normal anatomical confines or extension of the abdominal contents within the thorax. Thoracic hernias can be either congenital or acquired in aetiology. They can occur at the level of the thoracic inlet, chest wall or diaphragm. Thoracic hernias can be symptomatic or fortuitously discovered on imaging obtained for other indications. Complications of thoracic hernias include incarceration, trauma and strangulation with necrosis. Multiple imaging modalities are available to evaluate thoracic hernias. Radiographs usually offer the first clue to the diagnosis. Upper gastrointestinal radiography can identify bowel herniation and associated complications. CT and occasionally MR can be useful for further evaluation of these abnormalities, accurately identifying the type of hernia, its contents, associated complications, and provide a roadmap for surgical planning. In this article, we review the different types of thoracic hernias and the role of imaging in the evaluation of these hernias. TEACHING POINTS: • Protrusion of lung contents beyond the anatomic confines of the thorax constitutes a hernia. • Complications of thoracic hernias include incarceration, trauma and strangulation with necrosis. • Multiple imaging modalities are available to evaluate thoracic hernias. • CT is the imaging modality of choice for identifying thoracic hernias and their complications. • Imaging can provide a roadmap for surgical planning.

Keywords: Diaphragmatic hernia; Lung hernia; Pericardial hernia; Sternal dehiscence.

Fig. 1

Flowchart depicting the different types of thoracic hernias seen on imaging

Fig. 2

a, b A 67-year-old female being evaluated for pulmonary nodules and recent acute exacerbation of reactive airway disease. Axial CT (a) demonstrates the apicoposterior segment of right upper lobe (black arrow) extending into the cervical region. Volume-rendered image (b) clearly depicts the herniated lung above the clavicle and first rib (white arrow). Herniated lung causes a smooth impression on the trachea. These can cause tracheal deviation or compression

Fig. 3

a, b A 69-year-old female with a remote history of treated small-cell carcinoma and stent graft placement of the descending aorta presenting with slowly progressive left supraclavicular mass. Axial contrast-enhanced CT (CECT) image (a) above the level of the sternoclavicular joint and volume-rendered image (b) identifies a high, dilated and elongated aortic arch extending into the left cervical region. These aortic arches can dilate with aneurysm formation, which can cause a mass effect on the surrounding structures in the thoracic inlet

Fig. 4

a, b A 70-year-old female with a history of intercostal chest tube drainage for pleural effusion. Axial CT (a) and volume-rendered image (b) in a patient with previous right upper lobe wedge resection for a stage I lung cancer identifies focal intercostal herniation of the right upper lobe (white arrow). The neck of the hernia is narrow, indicating incarceration. In addition, there is abnormal orientation of the bronchovascular pedicle with narrowing of the bronchiole. Ground-glass opacities in the herniated lung indicate atelectasis (Movie 1). Elective repair is recommended for these hernias unless asymptomatic

Fig. 5

Coronal CT in a patient with a remote history of trauma demonstrates intercostal herniation of the liver

Fig. 6

a, b Coronal MIP demonstrates herniation of the mesenteric fat through the left 7th–8th intercostal space (a) with volume-rendered reconstruction (b)

Fig. 7

A 55-year-old male with a history of ascending aortic aneurysm status post-ascending aortic graft replacement. Axial CECT demonstrates sternal dehiscence with herniation of the right ventricle through the sternal defect. Only a thin layer of pericardium (white arrow) separates the skin from the myocardium

Fig. 8

a, b A 26-year-old male with a history of Shone’s complex, status post-coarctation repair, subaortic membrane resection and supravalvular mitral ring resection. Maximum intensity projection axial CECT images in the lung (a) and mediastinal (b) windows demonstrate focal herniation of the anterior segment of the right upper lobe (white arrow) between the ascending aorta and main pulmonary artery. This lung herniation is a result of focal absence of the pericardium

Fig. 9

a, b CT (a) and MRI (b) images through the heart demonstrate focal hernia of the right ventricular myocardium through a congenital anterior pericardial defect (white arrow)

Fig. 10

Axial T2-weighted MRI in a 1-month-old infant with a right posterior paravertebral mass. Non-contrast axial T2-weighted MRI identifies a right lateral myelomeningocele. Besides the herniated meninges, a neural placode (white star), which was not seen on CT (not shown), is also seen on the MRI, thus confirming this to be a lateral thoracic myelomeningocele

Fig. 11

A 55-year-old female with adenocarcinoma of the right upper lobe extending to hila status post right pneumonectomy. Follow-up surveillance CECT demonstrates a mediastinal shift with left lung herniation into the right hemithorax

Fig. 12

a–d A 5-year-old child with a history of right pneumonectomy for hypoplastic right lung and scimitar syndrome at the age of 1 year and now presenting with gradually increasing dyspnea. Axial CECT demonstrates a tissue expander in the right hemiothorax that was placed at the time of initial surgery (a, b). In addition, narrowing of the left bronchus is also seen, likely the cause of the post-pneumonectomy syndrome (white arrow). Follow-up axial CECT (c, d) with the upsized tissue expander in the right hemithorax demonstrates decreased narrowing of the left bronchus. In a growing child, these tissue expanders may need to be upsized over time to prevent these symptoms

Fig. 13

a A 46-year-old female being evaluated for right cardiophrenic angle opacity identified on a chest radiograph obtained during evaluation for pneumonia. Coronal CECT of the thorax identifies herniation of the omentum (dotted circle) through a clear defect in the right anterior-medial diaphragm (a) consistent with a Morgagni hernia. b, c A 49-year-old patient in the emergency department after trauma. Supine chest radiographs were suspicious for widening of the mediastinum. Axial (b) and coronal (c) CT clearly demonstrates a focal defect in the left anterior-medial diaphragm (white arrow) with herniation of peritoneal fat into the pericardium

Fig. 14

a A 44-year-old male with a recent history of blunt abdominal trauma, now presenting to the emergency department with upper abdominal pain. Axial CT with oral contrast identifies herniation of the stomach (white arrows) into the pericardium (arrowhead) with mild mass effect over the right ventricle. b A 56-year-old male with a remote history of blunt abdominal trauma and a recent diagnosis of Hodgkin's lymphoma. A pericardial mass was identified on a recent echocardiogram. Coronal CECT identifies herniation of the left lobe of the liver in the pericardium (white arrows). There is minimal mass effect over the right ventricle

Fig. 15

a A 79-year-old female with history of (h/o) heartburn on lying down after dinner. Left anterior oblique projection from the contrast oesophagogram identifies herniation of the gastro-oesophageal junction (white arrow) into the thorax; finding is consistent with type I or sliding hiatal hernia. b A 72-year-old male with morbid obesity and recurrent reflux pneumonitis. Lateral projection of a barium oesophagogram identifies intrathoracic herniation of the gastro-oesophageal junction with the gastric fundus, consistent with type III or mixed para-oesophageal hiatal hernia. c A 78-year-old female undergoing preoperative evaluation for transcatheter aortic valve replacement. Axial contrast CT identifies a large hiatal hernia containing stomach, large bowel, splenic vessels and pancreas in the hernia sac, compatible with a type IV hiatal hernia (Movie 2)

Fig. 16

a Axial ultrasound image of a 21-week-old foetus identifies stomach (star) at the level of the heart (white arrow) in the thorax. This finding is suggestive of a congenital diaphragmatic hernia. b Coronal images as seen on prenatal MRI (b) demonstrates multiple loops of fluid-filled bowel (white arrow) extending to the left thoracic apex, compatible with a Bochdalek hernia. There is associated ipsilateral lung hypoplasia

Fig. 17

a, b An 80-year-old male with blunt thoracic and abdominal trauma following a motor vehicle accident. Coronal contrast CT (b) identifies multiple left rib fractures. In addition, there is a focal defect at the lateral aspect of the left hemidiaphragm (white arrow). The patient presented 2 days later with increasing shortness of breath and a new opacity on the frontal radiograph. Coronal image from follow-up CT (b) identifies interval enlargement of the left lateral diaphragmatic defect with new herniation of the stomach, splenic flexure and omentum into the left thorax. Emergent surgical repair was performed for this hernia

Fig. 18

a An 80-year-old female being evaluated for transcatheter aortic valve replacement for severe aortic stenosis. Coronal maximum intensity projection image from a contrast-enhanced CT demonstrates a large left lateral abdominal wall hernia that originates at the lumbar triangle. The hernia sac is wide and contains small bowel, large bowel and omentum. It extends into the subcutaneous fascia of the thorax up to the level of the left 6th rib. b A 77-year-old male with lung cancer treated with stereotactic radiation therapy. Sagittal CECT obtained for surveillance demonstrates a large anterior abdominal wall hernia with subcutaneous extension into the pre-xiphoid portion of the anterior thorax

Fig. 19

A 48-year-old patient with new onset left chest wall pain after recent lung transplantation. Left intercostal strangulated lung hernia. Axial CECT image in a patient with left lung transplant. The focal herniated left lower lateral portion of the lung is strangulated (arrows) resulting in its heterogeneous opacification. The ground-glass opacities in the lingual and sub-segmental atelectasis in the left lower lobe anterior segment can also be secondary to the left lower lobe pulmonary embolus

Fig. 20

a, b A 92-year-old female with acute onset of severe upper abdominal pain, vomiting and nausea. Sagittal (a) and axial (b) contrast CT of the thorax (double rule out) demonstrated an intrathoracic stomach with organoaxial volvulus and gastric pneumatosis (Movie 3) requiring emergent surgical repair

Fig. 21

a, b An 86-year-old male with history of (h/o) melanoma, now presenting with chronic right upper abdominal pain. Coronal contrast CT (a) identifies a right retrosternal diaphragmatic hernia. Note the narrow neck of the hernia sac with herniation of the stomach (body, pylorus and antrum), colon and omentum into the mediastinum. This is an incarcerated hernia. The patient was offered elective repair, which was declined. The same patient presented with new onset of acute right upper quadrant pain after 2 months. Coronal contrast-enhanced CT (b) demonstrates severe dilation of the stomach with gastric outlet obstruction (Movie 4). The herniated hepatic flexure is not dilated. Adhesions within the hernia sac can lead to bowel obstruction and narrowing. These require urgent decompression of the distended stomach by placement of a gastric tube followed by surgical repair

Fig. 22

A 31-year-old patient who was on bed rest for lower extremity fracture, now presenting with new-onset chest pain following a severe bout of coughing. Coronal contrast CT demonstrates a large left diaphragmatic hernia, with left kidney, stomach and omentum present within the left thorax. Note decreased enhancement of the left kidney (white arrow) compared with the right kidney on these arterial phase images. The renal artery is normal; the renal vein cannot be evaluated on these arterial-phase images. Intraoperative findings were consistent with these findings demonstrating narrowing of the left renal vein with venous engorgement at the level of the diaphragmatic defect (Movie 5)

Fig. 23

a, b Coronal (a) venous phase and axial delayed excretory phase (b) CT from a patient with hydroneprosis identifies a focal defect in the right posterior diaphragm (white arrow) with herniation of right ureter into the thorax. There is ureteric obstruction at the neck of the hernia with resultant hydronephrosis