Imaging the Post-Thoracotomy Patient

Anatomic Changes and Postoperative Complications
Published:September 16, 2013DOI:https://doi.org/10.1016/j.rcl.2013.08.008

      Keywords

      Key points

      • Thoracotomy is used for lobectomy and pneumonectomy and produces expected postsurgical anatomic and physiologic changes. Distorted postsurgical anatomy can be challenging for the radiologist, but often follows typical patterns.
      • Complications following thoracotomy and lung resection can occur in both the early and late postoperative settings. Although some are relatively benign, other complications produce significantly increased morbidity and mortality.
      • Physiologic changes are associated with postpneumonectomy pulmonary edema, and anatomic changes can predispose to lobar torsion and cardiac herniation. These early postoperative complications are associated with devastating clinical outcomes if not recognized in a timely fashion.
      • Bronchopleural fistula and empyema are 2 serious complications of lung resection that can occur in the early or late postoperative setting; treatment of both can be challenging.

      Introduction

      With increasing use of thoracoscopic and minimally invasive surgery for lung resection, thoracotomy is typically reserved for procedures that require a larger surgical field, such as lobectomy and pneumonectomy. An understanding of the expected post-thoracotomy appearance of the chest is essential, as postoperative complications can make imaging findings additionally complex. Accurate identification and timely diagnosis of complications is crucial in minimizing increased morbidity and mortality.
      The objectives of this article are to review the expected appearance of the thorax after lung resection, as well as several postsurgical complications, using both radiography and multidetector-row computed tomography (MDCT).

      Pulmonary resection

      Lung resection is most frequently performed for the surgical treatment of bronchogenic carcinoma. Lobectomy is well established as the standard of care for curative resection in patients with early-stage non–small cell lung cancer, whereas pneumonectomy is more appropriate in patients with lung cancer who have multilobar or central disease.
      • Ginsberg R.J.
      • Rubinstein L.V.
      Randomized trial of lobectomy versus limited resection for T1 N0 non-small cell lung cancer. Lung Cancer Study Group.
      • Lederle F.A.
      Lobectomy versus limited resection in T1 N0 lung cancer.
      • Shields T.W.
      General thoracic surgery.
      The use of sublobar lung resection, such as wedge or segmentectomy, for early-stage lung cancer has been a popular topic of debate and is being performed more frequently.
      • Scott W.J.
      • Howington J.
      • Feigenberg S.
      • et al.
      Treatment of non-small cell lung cancer stage I and stage II: ACCP evidence-based clinical practice guidelines (2nd edition).
      • Donington J.S.
      Point: are limited resections appropriate in non-small cell lung cancer? Yes.
      Although sublobar resection has traditionally been reserved for high-risk patients unable to tolerate lobectomy, multiple retrospective studies have shown results of sublobar resection similar to those of lobectomy among well-selected patients with early-stage disease,
      • Koike T.
      • Yamato Y.
      • Yoshiya K.
      • et al.
      Intentional limited pulmonary resection for peripheral T1 N0 M0 small-sized lung cancer.
      • Okada M.
      • Koike T.
      • Higashiyama M.
      • et al.
      Radical sublobar resection for small-sized non-small cell lung cancer: a multicenter study.
      • Kilic A.
      • Schuchert M.J.
      • Pettiford B.L.
      • et al.
      Anatomic segmentectomy for stage I non-small cell lung cancer in the elderly.
      • Schuchert M.J.
      • Pettiford B.L.
      • Keeley S.
      • et al.
      Anatomic segmentectomy in the treatment of stage I non-small cell lung cancer.
      and a prospective clinical trial is currently under way to determine the efficacy of sublobar resection of small peripheral tumors.

      Cancer and Leukemia Group B. Comparison of different types of surgery in treating patients with stage IA non-small cell lung cancer. NCT00499330. Available at: http://clinicaltrials.gov/show/NCT00499330. Accessed July 15, 2013.

      Lung resection is also indicated for end-stage lung disease related to advanced emphysema, and prior infection with resultant bronchiectasis. Pulmonary trauma may also lead to surgical resection.
      • Shields T.W.
      General thoracic surgery.

      Partial Lung Resection

      With the goals of adequate treatment and preservation of maximum lung function, limited lung resection such as wedge resection, segmentectomy, and lobectomy is performed when possible. Such resection is often achieved with thoracoscopy rather than open thoracotomy, although the selection of surgical approach ultimately depends on the extent of disease, its anatomic distribution, and the clinical status of the patient.
      Nonanatomic wedge resection is a U-shaped or V-shaped resection with removal of lung that does not correspond to a lobar segment; the segmental bronchus and pulmonary artery typically remain, although the lung parenchyma is distorted. In segmentectomy, the segmental pulmonary bronchus and pulmonary artery are ligated and transected, with removal of the corresponding lung segment. Similarly, lobectomy includes isolation and transection of the lobar airway and artery, with removal of the lobe and its surrounding pleura. In cases of incomplete interlobar fissures, staple lines may be used to prevent postsurgical air leak.
      In cases of central endobronchial tumor, sleeve lobectomy can be performed to avoid pneumonectomy. This procedure includes en bloc resection of the diseased lung and a portion of the common airway, with careful end-to-end anastomosis of the transected airway. Vascularized tissue such as pleura or omentum is typically wrapped around the bronchial anastomosis for reinforcement.
      • Mentzer S.J.
      • Myers D.W.
      • Sugarbaker D.J.
      Sleeve lobectomy, segmentectomy, and thoracoscopy in the management of carcinoma of the lung.
      Sleeve lobectomy is most commonly used for right upper lobe resection (75%), owing to the longer length of the bronchus intermedius for anastomosis. Sleeve resection of the left upper and lower lobes is performed less commonly (16% and 8% of cases, respectively) because of the close proximity of the airway ostium and the adjacent pulmonary artery.
      • Mentzer S.J.
      • Myers D.W.
      • Sugarbaker D.J.
      Sleeve lobectomy, segmentectomy, and thoracoscopy in the management of carcinoma of the lung.
      Common radiographic findings in a patient following limited lung resection such as lobectomy include surgical material and volume loss (Fig. 1). Volume loss is indicated by elevation of the hemidiaphragm on the side of surgery, and increases as the degree of lung resection increases. The heart and mediastinum may also shift into the postsurgical hemithorax. It is often difficult to determine the full extent of lung resection on radiographs: the remaining ipsilateral lung shifts to fill the vacant surgical space, compensatory overinflation may occur, and anticipated anatomic landmarks become distorted.
      Figure thumbnail gr1
      Fig. 1Posteroanterior chest radiograph demonstrating right upper lobectomy. There is right-sided volume loss, and surgical clips are seen at the right hilum (arrow). The hyperinflated right middle and lower lobes have shifted to occupy the vacant surgical space.
      MDCT allows improved characterization of resultant postsurgical changes with high spatial resolution in 3 dimensions, best achieved by reconstructing thin-section images that facilitate multiplanar reformatted imaging. On computed tomography (CT), the presence of surgical material and changes in central lung anatomy are key to determining the type and location of limited lung resection. A peripheral suture line with intact segmental bronchi and vessels should suggest wedge resection, whereas central surgical clips and ligated bronchi and vessels indicate segmentectomy or lobectomy (Figs. 2 and 3).
      Figure thumbnail gr2
      Fig. 2Axial-oblique computed tomography (CT) image in lung window demonstrates right middle lobectomy. The lobar bronchus (arrowhead) is truncated and surrounded by high-density surgical material. A nearby suture line corresponds to the distorted right major fissure (arrow).
      Figure thumbnail gr3
      Fig. 3Right upper lobe sleeve lobectomy in a 58-year-old man. (A) Thin-section axial CT image illustrates changes following right upper lobe sleeve lobectomy. There is mild airway narrowing at the site of sleeve anastomosis. Reformatted coronal CT images in lung and soft-tissue windows (B, C) also show anastomosis of the smaller-caliber bronchus intermedius with the larger right mainstem bronchus. The anastomosis is reinforced with an intercostal flap (arrow), which is fat density and partially occupies the lumen, owing to the disparity in bronchial sizes.

      Pneumonectomy

      Among patients with multilobar or central disease, pneumonectomy is typically performed.
      • Shields T.W.
      General thoracic surgery.
      The most common technique is intrapleural pneumonectomy, which involves removal of the lung and its surrounding visceral pleura.
      • Kim E.A.
      • Lee K.S.
      • Shim Y.M.
      • et al.
      Radiographic and CT findings in complications following pulmonary resection.
      Similar to lobectomy, the bronchial stump is frequently reinforced with vascularized tissue such as pleura, intercostal muscle, or omentum to prevent stump dehiscence (Fig. 4). Extrapleural pneumonectomy includes resection of the lung, its visceral, parietal, and mediastinal pleura, and the associated pericardium and diaphragm.
      • Kim E.A.
      • Lee K.S.
      • Shim Y.M.
      • et al.
      Radiographic and CT findings in complications following pulmonary resection.
      This technique is typically used for locally advanced carcinoma, mesothelioma, and invasive thymoma.
      • Shields T.W.
      General thoracic surgery.
      Graft placement is often used to replace and reinforce the surgically altered pericardium and diaphragm (Fig. 5A, B). An intrapericardial technique includes incision of the pericardium for resection of tumor that surrounds or invades the hilar structures within the pericardial sac.
      • Kim E.A.
      • Lee K.S.
      • Shim Y.M.
      • et al.
      Radiographic and CT findings in complications following pulmonary resection.
      Similar to extrapleural technique, intrapericardial pneumonectomy typically results in placement of a graft after a portion of the pericardium has been excised (see Fig. 5C). Although not commonly performed, sleeve pneumonectomy includes resection of the lung and the ipsilateral mainstem bronchus, carina, and distal trachea, with anastomosis of the contralateral mainstem bronchus to the distal trachea.
      Figure thumbnail gr4
      Fig. 4(A) An intercostal muscle flap (arrow) has been created to reinforce the right lower lobe bronchial stump. (B) In a different patient, an omental flap has been used to reinforce the left lower lobe bronchial stump.
      Figure thumbnail gr5
      Fig. 5(A) Frontal chest radiograph soon after right extrapleural pneumonectomy. A thin lucency at the base of the right hemithorax (arrows) corresponds to diaphragmatic graft material, which will become hyperdense over time as it becomes embedded with proteinaceous material. (B) Coronal maximum-intensity projection CT image in a different patient demonstrates high-density graft material replacing portions of the pericardium and diaphragm following left extrapleural pneumonectomy. (C) Axial contrast-enhanced CT image reveals high-density graft material in a patient following left intrapericardial pneumonectomy. There is shift of the heart into the left hemithorax, where there is a small volume of fluid.
      ([B] Courtesy of Dr David Rice, Houston, TX.)
      The imaging appearance of the thorax changes incrementally after pneumonectomy, with gradual opacification of the newly vacant hemithorax.
      • Goodman L.R.
      Postoperative chest radiograph: II. Alterations after major intrathoracic surgery.
      Immediately after surgery, the postpneumonectomy space contains mostly air and a small amount of fluid (Fig. 6A). The trachea and mediastinal structures remain in the midline, and there is mild pulmonary vascular congestion in the remaining lung with engorged central vessels. During the first postoperative week, between one-half and two-thirds of the hemithorax gradually fills with fluid as air is slowly resorbed (see Fig. 6B, C). Fluid accumulates in the postoperative space at a variable rate. For instance, the surgical space may fill faster following extrapleural pneumonectomy, as quickly as 1 week, likely because of the absence of fluid resorption following excision of the pleura. The air-fluid level slowly rises, and although a small volume of air may sometimes remain at the apex with no clinical significance, the postpneumonectomy space is typically obliterated within weeks to months (see Fig. 6D, E).
      • Goodman L.R.
      Postoperative chest radiograph: II. Alterations after major intrathoracic surgery.
      During this time, the heart and mediastinal structures shift into the postpneumonectomy space posteriorly and the remaining lung hyperinflates anteriorly. Over time, up to one-third of pneumonectomy patients resorb much of the fluid in the postpneumonectomy space, leaving mediastinal structures and thickened fibrous tissue (see Fig. 6F); the remaining two-thirds of patients retain fluid within the surgical space.
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      Figure thumbnail gr6
      Fig. 6Frontal radiographs illustrate gradual opacification of the postpneumonectomy space in a patient following left pneumonectomy. (A) Immediately after surgery, air fills the postpneumonectomy space. The trachea is in the midline, and there is slight vascular congestion in the remaining lung. Subcutaneous air is noted. (B) Radiograph on postoperative day 1 demonstrates fluid occupying one-third of the left hemithorax. The left hemidiaphragm is elevated. (C) By postoperative day 4, roughly two-thirds of the pneumonectomy space is fluid-filled. (D) Three weeks after surgery, a small volume of air remains at the left apex. (E) Months later, the hemithorax is completely opacified; the heart has shifted into the left chest, and the right lung has hyperinflated (arrowheads). (F) Corresponding axial CT images in soft-tissue window confirms expected postoperative changes. Only a small volume of fluid remains in the postsurgical space. The esophagus (asterisk) is located adjacent to the left bronchial stump.
      Changes in patient position and inspiration may produce corresponding changes in air-fluid level in the pneumonectomy space. However, in an upright patient the air-fluid level should not drop more than 1.5 cm.
      • Goodman L.R.
      Postoperative chest radiograph: II. Alterations after major intrathoracic surgery.
      Similarly, air should not reappear in the pneumonectomy space when none was visible previously.
      Overall morbidity among patients undergoing pneumonectomy ranges from 30.6% to 59%, with mortality ranging from 3.3% to 10.8%.
      • Dancewicz M.
      • Kowalewski J.
      • Peplinski J.
      Factors associated with perioperative complications after pneumonectomy for primary carcinoma of the lung.
      • Alloubi I.
      • Jougon J.
      • Delcambre F.
      • et al.
      Early complications after pneumonectomy: retrospective study of 168 patients.
      • Algar F.J.
      • Alvarez A.
      • Salvatierra A.
      • et al.
      Predicting pulmonary complications after pneumonectomy for lung cancer.
      • Licker M.
      • Spiliopoulos A.
      • Frey J.G.
      • et al.
      Risk factors for early mortality and major complications following pneumonectomy for non-small cell carcinoma of the lung.
      • Marret E.
      • Miled F.
      • Bazelly B.
      • et al.
      Risk and protective factors for major complications after pneumonectomy for lung cancer.
      In a retrospective study of 242 patients followed over 12 years, Algar and colleagues
      • Algar F.J.
      • Alvarez A.
      • Salvatierra A.
      • et al.
      Predicting pulmonary complications after pneumonectomy for lung cancer.
      found morbidity of 59% and mortality of 5.4% among pneumonectomy patients. Multivariate analysis among these patients determined that underlying cardiovascular disease and chronic obstructive pulmonary disease with poor forced expiratory volume in 1 second (FEV1) are risk factors for patient morbidity following pneumonectomy. Other investigators also identified these risk factors in addition to advanced age.
      • Alloubi I.
      • Jougon J.
      • Delcambre F.
      • et al.
      Early complications after pneumonectomy: retrospective study of 168 patients.
      • Licker M.
      • Spiliopoulos A.
      • Frey J.G.
      • et al.
      Risk factors for early mortality and major complications following pneumonectomy for non-small cell carcinoma of the lung.
      Postoperative complications differ depending on the time that has elapsed following surgery (Box 1). Early complications include postpneumonectomy pulmonary edema, acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), and infection in the remaining lung. Postoperative hemorrhage can produce blood in the remaining lung parenchyma or in the pleural space. Abnormal pleural air may be due to anastomotic dehiscence resulting in bronchopleural fistula (BPF), with or without empyema. Of note, BPF and empyema are 2 complications that can also produce serious consequences in the late postoperative setting. Complex, potentially deadly early complications such as lobar torsion and cardiac herniation are rare.
      Post-thoracotomy complications following lung resection

        Early postoperative complications

      • Pulmonary edema
      • Acute lung injury/acute respiratory distress syndrome
      • Pneumonia
      • Hemorrhage/hemothorax
      • Chylothorax
      • Dehiscence of bronchial stump, formation of bronchopleural fistula
      • Esophagopleural fistula
      • Empyema
      • Lobar torsion
      • Cardiac herniation
      • Gossypiboma

        Late postoperative complications

      • Pneumonia
      • Disease recurrence (tumor, infection)
      • Dehiscence of bronchial stump, formation of bronchopleural fistula
      • Esophagopleural fistula
      • Empyema
      • Stricture of bronchial anastomosis
      • Pulmonary artery stump thrombosis
      • Postpneumonectomy syndrome
      • Herniation of lung or chest wall soft tissues via thoracotomy defect
      • Gossypiboma

      Early post-thoracotomy complications

      Postpneumonectomy Pulmonary Edema

      In the perioperative and early postpneumonectomy period, pulmonary edema can be a rapidly occurring, life-threatening complication. Its prevalence is reportedly 2.5% to 5% with a mortality rate historically greater than 80%.
      • Alloubi I.
      • Jougon J.
      • Delcambre F.
      • et al.
      Early complications after pneumonectomy: retrospective study of 168 patients.
      • Algar F.J.
      • Alvarez A.
      • Salvatierra A.
      • et al.
      Predicting pulmonary complications after pneumonectomy for lung cancer.
      • Turnage W.S.
      • Lunn J.J.
      Postpneumonectomy pulmonary edema. A retrospective analysis of associated variables.
      • Deslauriers J.
      • Aucoin A.
      • Gregoire J.
      Postpneumonectomy pulmonary edema.
      Postpneumonectomy pulmonary edema has been attributed to increased hydrostatic pressure applied to the remaining lung,
      • Zeldin R.A.
      • Normandin D.
      • Landtwing D.
      • et al.
      Postpneumonectomy pulmonary edema.
      • Verheijen-Breemhaar L.
      • Bogaard J.M.
      • van den Berg B.
      • et al.
      Postpneumonectomy pulmonary oedema.
      which is more common following right pneumonectomy; because of its smaller size, the left lung normally receives 45% of total pulmonary blood flow and contains 45% of the total lymphatic capacity when compared with the right.
      • Turnage W.S.
      • Lunn J.J.
      Postpneumonectomy pulmonary edema. A retrospective analysis of associated variables.
      • Gluecker T.
      • Capasso P.
      • Schnyder P.
      • et al.
      Clinical and radiologic features of pulmonary edema.
      Others believe that postpneumonectomy pulmonary edema is noncardiogenic, related to increased permeability of the capillary endothelial cell–alveolar wall barrier from vasoactive inflammatory mediators, a notion supported by histologic findings resembling ARDS.
      • Turnage W.S.
      • Lunn J.J.
      Postpneumonectomy pulmonary edema. A retrospective analysis of associated variables.
      Changes in fluid dynamics are compounded by perioperative fluid administration that decreases serum osmotic pressure, transfusion of blood products that not only adds fluid volume but may also contribute to changes in capillary permeability, and cardiac arrhythmia.
      • Gluecker T.
      • Capasso P.
      • Schnyder P.
      • et al.
      Clinical and radiologic features of pulmonary edema.
      Multivariate analyses among pneumonectomy patients found that liberal fluid administration and transfusion of even a single unit of any blood product significantly increased the risk for cardiovascular or respiratory complications.
      • Marret E.
      • Miled F.
      • Bazelly B.
      • et al.
      Risk and protective factors for major complications after pneumonectomy for lung cancer.
      • Blank R.S.
      • Hucklenbruch C.
      • Gurka K.K.
      • et al.
      Intraoperative factors and the risk of respiratory complications after pneumonectomy.
      In cases of mild pulmonary edema, subtle radiographic findings suggest the diagnosis, with fine peripheral Kerley lines, peribronchial cuffing, and increasingly indistinct central pulmonary vasculature with perihilar haziness. However, these findings may not be discernible on a postoperative portable chest radiograph, often with low inspiratory lung volumes and limited sensitivity. In cases of severe pulmonary edema, radiographs demonstrate central or widespread airspace opacification, although the rapid development of these radiographic findings may also suggest aspiration or ARDS as diagnostic possibilities (Fig. 7A). In cases of pulmonary edema, MDCT will often demonstrate interlobular septal thickening, peribronchial cuffing, and central-predominant lung opacification (see Fig. 7B). Pleural effusions may develop as fluid overwhelms the pulmonary lymphatics and enters the pleural space.
      Figure thumbnail gr7
      Fig. 7Pulmonary edema in a 50-year-old man after right pneumonectomy for lung cancer. (A) Chest radiograph on postoperative day 5 demonstrates left perihilar airspace opacity with indistinct pulmonary vessels and air bronchograms. (B) The accompanying CT image shows predominantly perihilar ground-glass opacity.

      Acute Lung Injury/Acute Respiratory Distress Syndrome

      Similar to postpneumonectomy pulmonary edema, ALI and ARDS are recognized complications of pneumonectomy that confer a poor prognosis. ALI and ARDS are differentiated by the ratio of partial pressure of arterial oxygen (Pao2) to fraction of inspired oxygen (Fio2): less than 300 mm Hg for ALI and less than 200 mm Hg for ARDS. Although the overall incidence of ALI and ARDS in patients following thoracotomy and lung resection is only 2.5% to 5%, associated mortality is often greater than 70%.
      • Dulu A.
      • Pastores S.M.
      • Park B.
      • et al.
      Prevalence and mortality of acute lung injury and ARDS after lung resection.
      • Hayes J.P.
      • Williams E.A.
      • Goldstraw P.
      • et al.
      Lung injury in patients following thoracotomy.
      • Kutlu C.A.
      • Williams E.A.
      • Evans T.W.
      • et al.
      Acute lung injury and acute respiratory distress syndrome after pulmonary resection.
      • Desai S.R.
      Acute respiratory distress syndrome: imaging of the injured lung.
      Described by Williams and colleagues
      • Williams E.
      • Goldstraw P.
      • Evans T.W.
      The complications of lung resection in adults: acute respiratory distress syndrome (ARDS).
      as high-permeability pulmonary edema that produces refractory hypoxemia, the underlying etiology of ARDS following pneumonectomy remains unclear. Possible explanations include activation of inflammatory cytokines, perioperative fluid overload contributing to greater blood flow to the remaining lung, and reoxygenation injury in the setting of lobectomy. These proposed insults lead to disruption of the barrier between the capillary endothelium and the adjacent alveolar wall.
      • Williams E.
      • Goldstraw P.
      • Evans T.W.
      The complications of lung resection in adults: acute respiratory distress syndrome (ARDS).
      Altered respiratory mechanics may also play a role, especially in patients who may suffer chronic lung disease, contributing to increased mortality in this group of patients.
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      Diagnosis is typically made with characteristic imaging findings and pulmonary artery wedge pressure less than 18 mm Hg, although wedge-pressure measurements can be inaccurately low in patients after pneumonectomy.
      • Kutlu C.A.
      • Williams E.A.
      • Evans T.W.
      • et al.
      Acute lung injury and acute respiratory distress syndrome after pulmonary resection.
      Although investigation by Kutlu and colleagues
      • Kutlu C.A.
      • Williams E.A.
      • Evans T.W.
      • et al.
      Acute lung injury and acute respiratory distress syndrome after pulmonary resection.
      found a higher frequency of ARDS in patients who are male, older than 60 years, and have lung cancer, other investigators found no useful preoperative predictors for lung injury.
      • Hayes J.P.
      • Williams E.A.
      • Goldstraw P.
      • et al.
      Lung injury in patients following thoracotomy.
      The median time of presentation following surgery is 4 days, as determined by Dulu and colleagues,
      • Dulu A.
      • Pastores S.M.
      • Park B.
      • et al.
      Prevalence and mortality of acute lung injury and ARDS after lung resection.
      who retrospectively observed more than 2000 lung-resection patients over 2 years in a tertiary-care cancer center. The overall rate of lung injury in these patients was 2.5%, with a higher relative percentage of pneumonectomy patients (7.9%; 10 of 126 patients) affected than those with lesser lung resection (3%; 31 of 1047 lobectomy patients).
      Although the imaging appearance of ARDS is characteristic, it is not specific. As inflammatory fluid and sloughed alveolar and capillary cells flood alveolar air spaces, radiographs demonstrate rapidly developing hazy opacities (Fig. 8A, B). Over a period of 36 hours, increasingly dense consolidation is noted. These abnormalities plateau after the initial exudation of fluid into the interstitial and alveolar spaces.
      • Desai S.R.
      Acute respiratory distress syndrome: imaging of the injured lung.
      Radiographic findings overlap with pneumonia and pulmonary edema, which can coexist in patients with ARDS. The absence or small volume of pleural effusion helps distinguish ARDS from frank pulmonary edema. Heterogeneous lung opacification is more easily recognized on CT, and a density gradient has been described, with greater opacification of the dependent lung than the nondependent lung that demonstrates ground-glass opacity or normal-appearing aeration (see Fig. 8C). This density gradient is thought to reflect passive atelectasis from edematous lung and may provide a protective effect to the atelectatic parenchyma, in comparison with the aerated lung above it, which is subjected to the stresses of mechanical ventilation and supplemental oxygenation.
      • Desai S.R.
      Acute respiratory distress syndrome: imaging of the injured lung.
      Figure thumbnail gr8
      Fig. 8A 59-year-old man with a complicated postoperative course following right extrapleural pneumonectomy for mesothelioma. (A) Radiograph 3 days after surgery demonstrates heterogeneous airspace opacity at the left lung base, consistent with pneumonia. (B) Two days later, there is heterogeneous opacification of the entire lung, compatible with acute respiratory distress syndrome. Increased air in the right postpneumonectomy space is also noted. (C) Corresponding CT image illustrates ground-glass opacity and mild septal thickening in the nondependent left lung; there is increasingly dense opacification of the atelectatic dependent lung. Small left effusion is also noted. (D) Repeat radiograph on postoperative day 6 shows further expansion of the pneumonectomy space with air, indicating airway dehiscence. There is flattening of the right hemidiaphragm and leftward shift of the mediastinum, indicating tension pneumothorax. Increased subcutaneous air is also noted (arrow). (E) Thin-section 1-mm axial CT image at the level of the carina shows a small volume of air tracking from the bronchial stump to the postpneumonectomy space (arrow).

      Pneumonia

      Postoperative pneumonia has an incidence ranging from 3.3% to 25% and can produce serious consequences.
      • Alloubi I.
      • Jougon J.
      • Delcambre F.
      • et al.
      Early complications after pneumonectomy: retrospective study of 168 patients.
      • Algar F.J.
      • Alvarez A.
      • Salvatierra A.
      • et al.
      Predicting pulmonary complications after pneumonectomy for lung cancer.
      • Pool K.L.
      • Munden R.F.
      • Vaporciyan A.
      • et al.
      Radiographic imaging features of thoracic complications after pneumonectomy in oncologic patients.
      • Schussler O.
      • Alifano M.
      • Dermine H.
      • et al.
      Postoperative pneumonia after major lung resection.
      • Diaz-Ravetllat V.
      • Ferrer M.
      • Gimferrer-Garolera J.M.
      • et al.
      Risk factors of postoperative nosocomial pneumonia after resection of bronchogenic carcinoma.
      In a prospective 5-year observational study of 604 patients with lung cancer undergoing resection, Diaz-Ravetllat and colleagues
      • Diaz-Ravetllat V.
      • Ferrer M.
      • Gimferrer-Garolera J.M.
      • et al.
      Risk factors of postoperative nosocomial pneumonia after resection of bronchogenic carcinoma.
      determined an incidence of postoperative pneumonia of 3.6%; mortality is 31.8%. Multivariate analysis of independent risk factors among these patients determined that predicted postoperative FEV1 lower than 50%, reintubation after surgery, and body mass index less than 26.5 kg/m2 inferred a higher risk of postoperative pneumonia. In the postoperative setting, pneumonia is frequently due to aspiration of secretions and colonization of atelectatic lung. Not only can direct contamination of the ventilator-dependent lung occur intraoperatively,
      • Schweizer A.
      • de Perrot M.
      • Hohn L.
      • et al.
      Massive contralateral pneumonia following thoracotomy for lung resection.
      but mechanical ventilation also alters normal respiratory clearance, promoting infection. The diagnosis of postoperative pneumonia may be challenging. Clinical signs such as fever and elevated white blood cell (WBC) count may not be specific for pneumonia, and pneumonia can have a delayed appearance on radiographs.
      The imaging appearance of pneumonia varies depending on the inciting event. For example, chest radiographs in a patient with aspiration-related pneumonia typically demonstrate rapid development of patchy, central, and basilar lung opacification (see Fig. 8A).
      • Franquet T.
      • Gimenez A.
      • Roson N.
      • et al.
      Aspiration diseases: findings, pitfalls, and differential diagnosis.
      Colonization of atelectatic lung may be difficult to appreciate amid an area of underventilated opacified lung, whereas lobar pneumonia conforms to lobar anatomy. CT is more sensitive for detecting areas of consolidation than is a portable, low-inspiratory-volume radiograph. Thickened, partially occluded airways are better seen on CT in a patient with poorly marginated bronchopneumonia. In cases of aspiration, ill-defined confluent and clustered nodular consolidation is typically seen in the posterior upper lobes and in the superior and posterior basal lower lobes, and areas of necrotizing bronchopneumonia or abscess may occur.
      • Franquet T.
      • Gimenez A.
      • Roson N.
      • et al.
      Aspiration diseases: findings, pitfalls, and differential diagnosis.

      Bronchopleural Fistula

      Leakage of air from the bronchial stump can occur in either the early or late postoperative periods. Dehiscence of the bronchial stump leading to BPF occurs in up to 5% of patients after pneumonectomy
      • Alloubi I.
      • Jougon J.
      • Delcambre F.
      • et al.
      Early complications after pneumonectomy: retrospective study of 168 patients.
      • Pool K.L.
      • Munden R.F.
      • Vaporciyan A.
      • et al.
      Radiographic imaging features of thoracic complications after pneumonectomy in oncologic patients.
      • Deschamps C.
      • Bernard A.
      • Nichols 3rd, F.C.
      • et al.
      Empyema and bronchopleural fistula after pneumonectomy: factors affecting incidence.
      • Asamura H.
      • Naruke T.
      • Tsuchiya R.
      • et al.
      Bronchopleural fistulas associated with lung cancer operations. Univariate and multivariate analysis of risk factors, management, and outcome.
      • Sirbu H.
      • Busch T.
      • Aleksic I.
      • et al.
      Bronchopleural fistula in the surgery of non-small cell lung cancer: incidence, risk factors, and management.
      • Wright C.D.
      • Wain J.C.
      • Mathisen D.J.
      • et al.
      Postpneumonectomy bronchopleural fistula after sutured bronchial closure: incidence, risk factors, and management.
      and can result in death in approximately 25% of patients, often related to aspiration of pleural contents or hemorrhage.
      • Asamura H.
      • Naruke T.
      • Tsuchiya R.
      • et al.
      Bronchopleural fistulas associated with lung cancer operations. Univariate and multivariate analysis of risk factors, management, and outcome.
      • Sirbu H.
      • Busch T.
      • Aleksic I.
      • et al.
      Bronchopleural fistula in the surgery of non-small cell lung cancer: incidence, risk factors, and management.
      • Wright C.D.
      • Wain J.C.
      • Mathisen D.J.
      • et al.
      Postpneumonectomy bronchopleural fistula after sutured bronchial closure: incidence, risk factors, and management.
      BPF also predisposes patients to infection of the pleural space, resulting in empyema, a serious complication that is discussed separately. There is a higher incidence of BPF among patients undergoing sleeve pneumonectomy, with BPF occurring in up to 15% of patients with mortality of up to 50%,
      • Okada M.
      • Kawaraya N.
      • Kujime K.
      • et al.
      Omentopexy for anastomotic dehiscence after tracheal sleeve pneumonectomy.
      presumably attributable to the surgical complexity of airway anastomosis. Similarly, several researchers have found that patients undergoing right pneumonectomy have a greater likelihood of bronchial stump dehiscence and fistula formation,
      • Deschamps C.
      • Bernard A.
      • Nichols 3rd, F.C.
      • et al.
      Empyema and bronchopleural fistula after pneumonectomy: factors affecting incidence.
      • Sirbu H.
      • Busch T.
      • Aleksic I.
      • et al.
      Bronchopleural fistula in the surgery of non-small cell lung cancer: incidence, risk factors, and management.
      • Wright C.D.
      • Wain J.C.
      • Mathisen D.J.
      • et al.
      Postpneumonectomy bronchopleural fistula after sutured bronchial closure: incidence, risk factors, and management.
      related to a greater diameter of the right bronchial stump in comparison with the left. Hollaus and colleagues
      • Hollaus P.H.
      • Setinek U.
      • Lax F.
      • et al.
      Risk factors for bronchopleural fistula after pneumonectomy: stump size does matter.
      found that a bronchial stump diameter of greater than 25 mm was associated with a greater incidence of BPF formation. Others suggest greater likelihood after right pneumonectomy because of shorter stump length and greater vulnerability of the stump to ischemia, owing to a single bronchial artery supply.
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      Postoperative mechanical ventilation is also a significant risk factor, related not only to the positive pressure of mechanical ventilation but also the other respiratory complications that make it necessary.
      • Sirbu H.
      • Busch T.
      • Aleksic I.
      • et al.
      Bronchopleural fistula in the surgery of non-small cell lung cancer: incidence, risk factors, and management.
      • Wright C.D.
      • Wain J.C.
      • Mathisen D.J.
      • et al.
      Postpneumonectomy bronchopleural fistula after sutured bronchial closure: incidence, risk factors, and management.
      A multivariate analysis by Asamura and colleagues
      • Asamura H.
      • Naruke T.
      • Tsuchiya R.
      • et al.
      Bronchopleural fistulas associated with lung cancer operations. Univariate and multivariate analysis of risk factors, management, and outcome.
      involving more than 2300 patients over nearly 30 years found that preoperative radiation therapy, residual malignancy at the bronchial stump, and diabetes increased the risk of BPF formation.
      In the early postoperative setting, dehiscence of the bronchial stump and BPF formation typically occur in the first postoperative week.
      • Wain J.C.
      Management of late postpneumonectomy empyema and bronchopleural fistula.
      Radiographs show failure of the postpneumonectomy space to fill with fluid, as there is persistent or increasing pleural air (see Fig. 8A, B, D). Abnormal air may also be identified in the mediastinum or tracking into the subcutaneous tissues via the surgical incision site or a chest tube tract. On an upright radiograph, the air-fluid level in the postpneumonectomy space should not drop by more than 1.5 cm; if so, BPF should be suspected. Concurrent shift of the mediastinum away from the surgical space should also suggest airway dehiscence and fistula formation.
      • Goodman L.R.
      Postoperative chest radiograph: II. Alterations after major intrathoracic surgery.
      • Wechsler R.J.
      • Goodman L.R.
      Mediastinal position and air-fluid height after pneumonectomy: the effect of the respiratory cycle.
      Similarly, if the postoperative hemithorax has become completely opacified with fluid, a new air-fluid level should raise suspicion of BPF.
      MDCT imaging can serve as a valuable tool in cases of suspected BPF. In many cases, thin-section images on the order of 1 to 2 mm can demonstrate direct evidence of fistulization, with a clear tract connecting the bronchial lumen to the surgical space (see Fig. 8E). Indirect signs such as small bubbles of air around the bronchial stump should also suggest BPF.
      • Seo H.
      • Kim T.J.
      • Jin K.N.
      • et al.
      Multi-detector row computed tomographic evaluation of bronchopleural fistula: correlation with clinical, bronchoscopic, and surgical findings.
      Spontaneous closure of small BPF has been reported in up to one-third of patients.
      • Wain J.C.
      Management of late postpneumonectomy empyema and bronchopleural fistula.
      Chest-tube drainage is inadequate treatment for the majority of patients. Surgical intervention has traditionally involved resuturing of the stump and reinforcing the anastomosis with placement of a flap of vascularized tissue such as omentum or muscle, which has produced successful treatment in nearly 90% of patients.
      • Asamura H.
      • Naruke T.
      • Tsuchiya R.
      • et al.
      Bronchopleural fistulas associated with lung cancer operations. Univariate and multivariate analysis of risk factors, management, and outcome.
      • Wain J.C.
      Management of late postpneumonectomy empyema and bronchopleural fistula.
      More recently, endobronchial placement of a unidirectional valve within the stump proximal to the fistula has been used successfully and with increasing frequency.
      • Feller-Kopman D.
      • Bechara R.
      • Garland R.
      • et al.
      Use of a removable endobronchial valve for the treatment of bronchopleural fistula.
      In lobectomy patients, BPF that fails other treatment methods may require completion pneumonectomy.

      Empyema

      Like BPF, empyema is a potentially fatal complication that can occur in the early or late postoperative periods. In fact, empyema is associated with dehiscence of the bronchial stump in up to 75% to 80% of cases.
      • Wain J.C.
      Management of late postpneumonectomy empyema and bronchopleural fistula.
      • Schneiter D.
      • Cassina P.
      • Korom S.
      • et al.
      Accelerated treatment for early and late postpneumonectomy empyema.
      Therefore, conditions that place patients at higher risk of BPF also convey higher risk of empyema: completion pneumonectomy after previous lobectomy, right pneumonectomy, preoperative radiation, and postoperative mechanical ventilation.
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      • Wain J.C.
      Management of late postpneumonectomy empyema and bronchopleural fistula.
      • Fujimoto T.
      • Zaboura G.
      • Fechner S.
      • et al.
      Completion pneumonectomy: current indications, complications, and results.
      In the early postoperative setting, when not attributed to airway dehiscence and BPF, infection of the pleural space is often due to gross contamination of the surgical field. This contamination can be related to incompletely treated or residual infection, injury to the mid-esophagus or airway during surgery, or mediastinal lymph node dissection.
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      • Wain J.C.
      Management of late postpneumonectomy empyema and bronchopleural fistula.
      However, with improved surgical technique and widespread use of perioperative antibiotics, empyema is increasingly uncommon, with an overall reported incidence of 2% to 7.5%.
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      • Alloubi I.
      • Jougon J.
      • Delcambre F.
      • et al.
      Early complications after pneumonectomy: retrospective study of 168 patients.
      • Pool K.L.
      • Munden R.F.
      • Vaporciyan A.
      • et al.
      Radiographic imaging features of thoracic complications after pneumonectomy in oncologic patients.
      • Deschamps C.
      • Bernard A.
      • Nichols 3rd, F.C.
      • et al.
      Empyema and bronchopleural fistula after pneumonectomy: factors affecting incidence.
      Patients often show signs of systemic toxicity, with fever, elevated WBC count, and deterioration of clinical status.
      Radiographic findings that suggest early postoperative empyema include rapid fluid-filling of the postpneumonectomy space and shift of the mediastinum to the contralateral hemithorax.
      • Goodman L.R.
      Postoperative chest radiograph: II. Alterations after major intrathoracic surgery.
      CT typically demonstrates expansion of the postpneumonectomy space with fluid, which is often complex with intermediate density, frequently producing mass effect on the adjacent heart and mediastinal structures (Fig. 9).
      • Chae E.J.
      • Seo J.B.
      • Kim S.Y.
      • et al.
      Radiographic and CT findings of thoracic complications after pneumonectomy.
      • Heater K.
      • Revzani L.
      • Rubin J.M.
      CT evaluation of empyema in the postpneumonectomy space.
      Rather than its usual concave appearance, the mediastinal border of the postpneumonectomy space is straightened or bulges convexly toward the mediastinum. CT also frequently demonstrates irregular thickening of the parietal pleura with enhancement following administration of intravenous contrast. Unfortunately, the absence of irregular pleural thickening does not exclude the diagnosis of empyema.
      Figure thumbnail gr9
      Fig. 9Empyema in a 79-year-old man after right upper lobectomy. (A) Axial CT image shows an air-fluid level in the superior right hemithorax with associated pleural thickening. There is high-density surgical material at the hilum, and the bronchus intermedius is filled with debris. (B) Reformatted coronal CT image illustrates empyema compressing the atelectatic right lung (R). A small amount of pleural fluid (white asterisks) is seen at both lung bases, and there is ascites (black asterisks) in the upper abdomen.
      Immediate treatment of empyema involves draining the infected fluid via closed-tube thoracostomy in addition to systemic antibiotic therapy. However, complete and long-lasting sterilization of the pleural space is often challenging. Historically, obliteration of the pleural space involved thoracoplasty, with collapse of the hemithorax resulting in functional and cosmetic deformity.
      • Miller Jr., J.I.
      The history of surgery of empyema, thoracoplasty, Eloesser flap, and muscle flap transposition.
      In postpneumonectomy patients with chronic empyema, the modified Clagett procedure remains a commonly used surgical strategy: a multistage surgery which entails open thoracostomy, reinforcement of the bronchial stump in cases of recurrent BPF, irrigation of the pleural space with antibiotics, and closure of the chest wall.
      • Clagett O.T.
      • Geraci J.E.
      A procedure for the management of postpneumonectomy empyema.
      • Pairolero P.C.
      • Arnold P.G.
      • Trastek V.F.
      • et al.
      Postpneumonectomy empyema. The role of intrathoracic muscle transposition.
      This technique is successful in up to 90% of patients.
      • Zaheer S.
      • Allen M.S.
      • Cassivi S.D.
      • et al.
      Postpneumonectomy empyema: results after the Clagett procedure.
      Although traditionally used in lobectomy patients with empyema, a modified Eloesser flap procedure can also be used in pneumonectomy patients; this technique involves creation of an inverted U-shaped chest wall soft-tissue flap (Fig. 10). The underlying ribs are partially excised, and the empyema cavity is entered and evacuated. The skin and subcutaneous flap is then tucked into the open thoracostomy space and securely sutured.
      • Thourani V.H.
      • Lancaster R.T.
      • Mansour K.A.
      • et al.
      Twenty-six years of experience with the modified Eloesser flap.
      • Symbas P.N.
      • Nugent J.T.
      • Abbott O.A.
      • et al.
      Nontuberculous pleural empyema in adults. The role of a modified Eloesser procedure in its management.
      • Shapiro M.P.
      • Gale M.E.
      • Daly B.D.
      Eloesser window thoracostomy for treatment of empyema: radiographic appearance.
      The thoracostomy space is packed with iodinated gauze, creating a characteristic appearance on CT. In comparison with the Clagett procedure that involves closure of the chest wall, the Eloesser flap is considered a permanent procedure that allows one-way drainage of the empyema.
      Figure thumbnail gr10
      Fig. 10Creation of an Eloesser flap in a right-pneumonectomy patient with recurrent bronchopleural fistula and empyema. Frontal chest radiograph (A) and corresponding coronal CT image (B) demonstrate partial resection of several right ribs. The right chest cavity communicates with the outside. Iodinated gauze (arrows) lies in the dependent chest cavity.

      Hemothorax

      In the early postoperative period, a small amount of hemorrhage is attributed to disruption of small vessels during tissue dissection. Clinically significant bleeding is uncommon, reported in less than 1% of pneumonectomy patients.
      • Pool K.L.
      • Munden R.F.
      • Vaporciyan A.
      • et al.
      Radiographic imaging features of thoracic complications after pneumonectomy in oncologic patients.
      However, significant hemorrhage may occur if there is injury to a pulmonary, bronchial, internal mammary, or intercostal vessel. Vessels in the operative field may be friable and prone to disruption from infection, malignancy, or prior radiation. Rarely, inadequate hemostasis can be attributed to coagulopathy. In cases of hemothorax, fluid will rapidly accumulate in the vacant hemithorax, and the patient will ultimately demonstrate clinical signs of blood loss.
      In the perioperative period, radiographs in patients with significant bleeding will demonstrate rapid accumulation of fluid in the vacant pleural space (Fig. 11A, B). However, if hemorrhage occurs over the first several days after surgery, accurate diagnosis may be challenging; accumulation of blood may be less conspicuous as serous fluid normally fills the postpneumonectomy space. Loculated hemorrhage or hematoma may be more conspicuous if located along the superior, lateral, or medial margin of the postsurgical space (see Fig. 11C). Mass effect on the mediastinum and shift toward the contralateral side are helpful findings. CT is useful in demonstrating high- to intermediate-density fluid or heterogeneous material in the pleural space, depending on the age of blood products at the time of imaging. A hematocrit level may also be present if there is layering of blood products in the dependent thorax.
      Figure thumbnail gr11
      Fig. 11Large hemothorax shortly after right pneumonectomy. (A) Frontal chest radiograph immediately after surgery demonstrates a mostly air-filled postpneumonectomy space. There is elevation of the right hemidiaphragm, and there is small subcutaneous emphysema. (B) One day later, repeat portable chest radiograph shows complete opacification of the right hemithorax with shift of the heart away from the right pneumonectomy space. (C) Corresponding coronal noncontrast CT image in soft-tissue window demonstrates a large heterogeneous area of hemorrhage (H) in the superior thorax. Small postsurgical air and simple-appearing fluid is seen inferiorly.
      Less commonly, abnormal fluid in the pleural space may be related to injury of the thoracic duct. Chylothorax is reported in only 1% of patients following pneumonectomy but may be seen after dissection of the subaortic region or the inferior right paravertebral region, resulting in damage to the thoracic duct.
      • Pool K.L.
      • Munden R.F.
      • Vaporciyan A.
      • et al.
      Radiographic imaging features of thoracic complications after pneumonectomy in oncologic patients.
      The low-pressure lymphatic system slowly spills fluid into the pleural space; fluid density is variable depending on its protein content, but is typically of low attenuation owing to its fat composition.

      Lobar Torsion

      Lobar torsion is a rare and serious complication of lobectomy in the early postoperative setting, with an incidence of 0.09% to 0.2%.
      • Yamane M.
      • Sano Y.
      • Nagahiro I.
      • et al.
      Lobar torsion after pulmonary resection for lung cancer.
      • Cable D.G.
      • Deschamps C.
      • Allen M.S.
      • et al.
      Lobar torsion after pulmonary resection: presentation and outcome.
      Most lobar torsion involves the right middle lobe as it moves cranially following removal of the right upper lobe or, less commonly, the left upper lobe as it moves caudally after removal of the left lower lobe. Following surgery, air and fluid in the pleural space provide little resistance to movement of the remaining lung. As lobes shift to fill the newly vacant space, partial or complete rotation of the affected lobe occurs around its bronchovascular pedicle at the hilum. Occlusion of airways and pulmonary arteries produces hypoxia and ischemia; hemorrhagic infarction may occur as a result of obstructed venous outflow. Patients often experience pronounced deterioration of clinical status with compromised respiratory function, often with fever and elevated WBC count; the mean time to diagnosis is 6 to 10 days, and treatment requires urgent reoperation.
      • Yamane M.
      • Sano Y.
      • Nagahiro I.
      • et al.
      Lobar torsion after pulmonary resection for lung cancer.
      • Cable D.G.
      • Deschamps C.
      • Allen M.S.
      • et al.
      Lobar torsion after pulmonary resection: presentation and outcome.
      Findings of lobar torsion on chest radiographs are suggestive but not specific, mimicking atelectatic lung or pleural hematoma (Fig. 12). In cases of torsion, the affected lobe shifts into the vacant postsurgical space and demonstrates increasing opacification, often within hours.
      • Munk P.L.
      • Vellet A.D.
      • Zwirewich C.
      Torsion of the upper lobe of the lung after surgery: findings on pulmonary angiography.
      • Spizarny D.L.
      • Shetty P.C.
      • Lewis Jr., J.W.
      Lung torsion: preoperative diagnosis with angiography and computed tomography.
      In cases of right middle lobe torsion, hazy opacity in the right paratracheal region becomes increasingly dense (Fig. 13A, B). The torsed lobe typically increases in size as venous outflow obstruction occurs, and bulging of the fissure may be seen, producing perihilar convexity. MDCT provides better characterization of distorted postoperative anatomy, which is optimized with administration of intravenous contrast (see Fig. 13C, D). Tapering or occlusion of the proximal lobar bronchus is present. The torsed lobe demonstrates heterogeneous ground-glass opacity that becomes increasingly dense with bulging of the fissure. There is amorphous soft-tissue density at the hilum as the bronchovascular pedicle has twisted on itself, and a suture line may be seen in an unexpected location, a finding that may be better appreciated by the thoracic surgeon. When intravenous contrast has been administered, the corresponding pulmonary artery is tapered and obliterated much like the lobar bronchus, and the two have an abnormal orientation. Poor pulmonary arterial enhancement of the affected lobe also helps make the diagnosis of lobar torsion.
      • Pool K.L.
      • Munden R.F.
      • Vaporciyan A.
      • et al.
      Radiographic imaging features of thoracic complications after pneumonectomy in oncologic patients.
      Figure thumbnail gr12
      Fig. 12Hematoma mimicking right middle lobe torsion in a 64-year-old man shortly after right upper lobectomy. (A) Portable chest radiograph obtained postoperative day 1 illustrates an oblong opacity in the right paratracheal region (arrow). There is fullness of the right hilum. Right hilar surgical clips are not easily seen on this radiograph, but a transected right posterior rib indicates recent thoracotomy (arrowhead). (B) Two days later, the right paratracheal opacity has increased in size, demonstrating a convex margin that is contiguous with the right hilum. The patient experienced a mild drop in hematocrit. Bronchoscopy demonstrated patency of the right middle lobe bronchus.
      Figure thumbnail gr13
      Fig. 13Right middle lobe torsion in a 62-year-old man following right upper lobectomy for bronchogenic carcinoma. (A) Frontal chest radiograph shortly after surgery demonstrates right-sided volume loss with elevation of the right hemidiaphragm. (B) On postoperative day 2, there is increasing opacification of the medial right upper lung. Corresponding coronal CT image (C) demonstrates mottled ground-glass opacification (long arrow) of the torsed right middle lobe. There is denser opacification (short arrow) at the hilum, where the lobe has rotated on its bronchovascular pedicle. No patent bronchus is seen. (D) Although pulmonary vessels are opacified with intravenous contrast, none are seen perfusing the ischemic right middle lobe.

      Cardiac Herniation

      Herniation of the heart through a pericardial defect is a very rare but often lethal complication that is typically associated with intrapericardial pneumonectomy. Early recognition is essential for survival; even when recognized, mortality approaches 50%.
      • Arndt R.D.
      • Frank C.G.
      • Schmitz A.L.
      • et al.
      Cardiac herniation with volvulus after pneumonectomy.
      • Mehanna M.J.
      • Israel G.M.
      • Katigbak M.
      • et al.
      Cardiac herniation after right pneumonectomy: case report and review of the literature.
      Cardiac herniation occurs almost exclusively in the immediate postoperative period, and is more common after right pneumonectomy with rotation of the heart along its craniocaudal axis. Inciting factors are thought to be associated with acutely increased intrathoracic pressure related to coughing, patient repositioning, positive pressure ventilation, rapid reexpansion of the remaining lung, or suction from drainage tubing.
      • Mehanna M.J.
      • Israel G.M.
      • Katigbak M.
      • et al.
      Cardiac herniation after right pneumonectomy: case report and review of the literature.
      Clinical signs of herniation depend on the side of the pericardial defect: on the right, there are signs of obstructed venous return to the heart with hypotension and reflex tachycardia. Acute superior vena cava syndrome with distended jugular veins has been described. If the pericardial defect is on the left, compression and constriction of the left heart by the edges of the pericardial defect can produce arrhythmia, myocardial ischemia, and infarction.
      Clinical findings of cardiac herniation are nonspecific and, given the rarity of the condition, cardiac herniation may not be the first diagnostic consideration. Chest radiographs may be the first and only diagnostic test to suggest the diagnosis. In cases of herniation of the heart through a right pericardial defect, rotation of the heart results in the cardiac apex pointing to the right, and a globular heart border protrudes into the right chest. Notching of the vascular pedicle has also been described. When herniation occurs through a left pericardial defect, there is a spherical left heart border with the left ventricular apex displaced laterally and posteriorly toward the costophrenic sulcus. There is an incisura between the great vessels and the herniated left heart border. On either side, the pericardial sac may appear air filled, and there is frequently displacement, abnormal orientation, or kinking of indwelling tubes and catheters.
      • Arndt R.D.
      • Frank C.G.
      • Schmitz A.L.
      • et al.
      Cardiac herniation with volvulus after pneumonectomy.
      • Mehanna M.J.
      • Israel G.M.
      • Katigbak M.
      • et al.
      Cardiac herniation after right pneumonectomy: case report and review of the literature.

      Late post-thoracotomy complications

      In the late post-thoracotomy period compensatory anatomic changes have occurred, producing expected and static imaging appearances. In lobectomy patients, there is evidence of volume loss: imaging shows elevation of the hilum or diaphragm. In both lobectomy patients and pneumonectomy patients, the heart and mediastinal structures may shift toward the surgical space. Pneumonectomy patients will demonstrate opacification of the postsurgical space by a variable amount of fluid and, if present, thickened fibrous pleura. Post-thoracotomy changes sometimes lead to benign yet unexpected imaging findings. Lung or extrapleural fat can herniate through a thoracotomy defect, for example (Figs. 14 and 15). Rarely, in the case of postpneumonectomy syndrome, shifting structures can produce clinical symptoms.
      Figure thumbnail gr14
      Fig. 14The posterior margin of the right upper lobe herniates through a wide-necked thoracotomy defect (arrows) following partial excision of the right seventh rib for right lower lobectomy.
      Figure thumbnail gr15
      Fig. 15(A) Frontal chest radiograph demonstrates a smoothly marginated opacity at the lateral margin of the left mid lung (arrow), initially worrisome for a pleural mass such as metastasis. (B) Corresponding coronal CT image illustrates herniation of fat and soft tissue through the chest wall into the extrapleural space at a level corresponding to prior surgery.

      Postpneumonectomy Syndrome

      Postpneumonectomy syndrome is an uncommon complication that occurs in the late postoperative period, in which exaggerated anatomic changes produce respiratory symptoms. The syndrome is typically seen in children, young adults, and women, who presumably have greater tissue compliance than older patients and men.
      • Mehran R.J.
      • Deslauriers J.
      Late complications. Postpneumonectomy syndrome.
      • Shepard J.A.
      • Grillo H.C.
      • McLoud T.C.
      • et al.
      Right-pneumonectomy syndrome: radiologic findings and CT correlation.
      The syndrome is much more commonly seen after right pneumonectomy,
      • Valji A.M.
      • Maziak D.E.
      • Shamji F.M.
      • et al.
      Postpneumonectomy syndrome: recognition and management.
      • Soll C.
      • Hahnloser D.
      • Frauenfelder T.
      • et al.
      The postpneumonectomy syndrome: clinical presentation and treatment.
      because of the relatively large right hemithorax. Following right pneumonectomy, the heart and mediastinum shift into the surgical space and move posteriorly while the overinflated left lung shifts medially and anteriorly. The cardiac apex is rotated in a counterclockwise fashion around the craniocaudal axis toward the right lateral chest. Like the remaining lung, the trachea and left mainstem bronchus are rotated to the right; they are stretched and compressed by both the aortic arch and left pulmonary artery superiorly and anteriorly, and by the descending aorta and vertebral column posteriorly. Resultant airway narrowing produces stridor and promotes recurrent infection from impaired clearance. Over time, affected airways can develop tracheomalacia or bronchomalacia, and the resultant collapse of the air column during exhalation leads to exaggerated symptoms. In patients without tracheomalacia, in whom airway integrity is maintained, surgical repositioning of the mediastinum can be achieved with placement of expandable (often saline- or silicone-filled) prostheses in the pneumonectomy space.
      • Soll C.
      • Hahnloser D.
      • Frauenfelder T.
      • et al.
      The postpneumonectomy syndrome: clinical presentation and treatment.
      • Grillo H.C.
      • Shepard J.A.
      • Mathisen D.J.
      • et al.
      Postpneumonectomy syndrome: diagnosis, management, and results.
      • Shen K.R.
      • Wain J.C.
      • Wright C.D.
      • et al.
      Postpneumonectomy syndrome: surgical management and long-term results.
      Symptomatic relief is typically immediate and lasting, with very low morbidity and mortality.
      In patients with postpneumonectomy syndrome, chest radiographs will demonstrate pronounced displacement of the trachea, mediastinum, and heart into the pneumonectomy space, with the cardiac apex pointing toward the posterior lateral hemithorax. Air may be seen on either side of the mediastinum as the remaining lung hyperexpands and crosses the midline into the pneumonectomy space. Although volume loss should be appreciated, the extent of lung resection may be difficult to determine. There is minimal opacification of the pneumonectomy space, and rib resection may not have been performed if thoracotomy has occurred in a young patient. CT will clearly illustrate narrowing and compression of the distal trachea and mainstem bronchus (Fig. 16A) by adjacent vascular structures. In a pneumonectomy patient with intrathoracic prostheses (see Fig. 16B), prevention or treatment of postpneumonectomy syndrome should be considered.
      Figure thumbnail gr16
      Fig. 16Postpneumonectomy syndrome in a 43-year-old woman with stridor and remote history of right pneumonectomy. (A) Axial CT image in lung window reveals displacement of the heart into the posterior right hemithorax. Compensatory hyperinflation of the left lung has occurred. The left lower lobe bronchus is severely compressed by the left pulmonary artery anteriorly (white arrowhead) and descending aorta posteriorly (black arrowhead). (B) Portable chest radiograph following surgical correction of postpneumonectomy syndrome. Round silicone implants now occupy much of the right hemithorax, and the cardiac silhouette overlies the midline.

      Pulmonary Artery Stump Thrombosis

      Pulmonary artery thromboembolism is frequently suspected in hospitalized postoperative patients, especially in patients with underlying malignancy. However, in patients who have undergone pneumonectomy, thrombosis of the remaining pulmonary artery stump occurs not infrequently and is often encountered incidentally on late postoperative surveillance imaging (Fig. 17). In a retrospective study of 89 postpneumonectomy patients, Kwek and Wittram
      • Kwek B.H.
      • Wittram C.
      Postpneumonectomy pulmonary artery stump thrombosis: CT features and imaging follow-up.
      identified pulmonary artery stump thrombosis in 12.4% of patients. In this study, contrast-enhanced CT images demonstrated low-density thrombi with both convex and concave margins to the adjacent vessel wall, indicating both acute-appearing and chronic-appearing thrombus. During a mean follow-up time of approximately 2 years, none of the affected patients had propagation of thrombus outside the pulmonary artery stump, and of the 4 patients who demonstrated reduction in thrombus size, only 1 had received anticoagulation, suggesting a benign natural history. Thrombi were seen with near equal frequency following both right and left pneumonectomy, even though the right pulmonary artery stump is typically longer than the left. In addition, patients with stump thrombus had a significantly longer stump length than those without thrombus, suggesting incremental changes in blood-flow dynamics with varying stump length.
      • Kwek B.H.
      • Wittram C.
      Postpneumonectomy pulmonary artery stump thrombosis: CT features and imaging follow-up.
      Figure thumbnail gr17
      Fig. 17Pulmonary artery thrombus in a 68-year-old woman status post extrapleural right pneumonectomy. Axial contrast-enhanced CT image demonstrates a convex filling defect within the right pulmonary artery stump (arrow). The finding was incidentally discovered on outpatient follow-up imaging; the patient was asymptomatic and received no anticoagulation. Surgical clips are seen at the stumps of the right mainstem bronchus and pulmonary artery, and high-density graft material is present posterolaterally, where there is evidence of prior chest wall resection and thoracoplasty. An Eloesser window (not included on image) accounts for air in the right hemithorax.

      Late Bronchopleural Fistula and Empyema

      Both BPF and empyema can occur months to years after surgery, although the underlying etiology often differs from the early postoperative setting. In the late postoperative period, BPF is often due to recurrent malignancy or infection causing erosion of the bronchial stump. Imaging findings are similar in both early and late settings. New locules of air or a new air-fluid level in a previously opacified postpneumonectomy space may be encountered more often on chest radiographs of late postoperative patients.
      As in early postoperative cases, empyema is often directly related to BPF. However, when the bronchial stump is intact, empyema is typically due to hematogenous spread of infection. In the late postoperative period pneumonectomy patients often have thickened, fibrous pleura and residual fluid in the postpneumonectomy space, regardless of infection. Therefore, secondary signs of empyema such as contralateral displacement of cardiomediastinal structures by a bulging fluid collection are especially helpful. Without such imaging clues, diagnostic thoracentesis may be needed.

      Gossypiboma

      Although gossypiboma technically refers to a cotton matrix, the term is generally used for retained surgical material not limited to surgical sponges. The material incites an aseptic foreign-body reaction with fibroblast proliferation and encapsulation, but it can also serve as a nidus for infection.
      • Park H.J.
      • Im S.A.
      • Chun H.J.
      • et al.
      Changes in CT appearance of intrathoracic gossypiboma over 10 years.
      • Sheehan R.E.
      • Sheppard M.N.
      • Hansell D.M.
      Retained intrathoracic surgical swab: CT appearances.
      Although exceedingly uncommon, retained surgical material in the thorax is typically encountered in the pleural space. Despite the widespread use of gauze embedded with radiodense material, identification by imaging can be challenging. On chest radiographs, gossypiboma has an appearance of an unusual opacity or mass that changes little over time.
      • Park H.J.
      • Im S.A.
      • Chun H.J.
      • et al.
      Changes in CT appearance of intrathoracic gossypiboma over 10 years.
      High density can sometimes be confused with surgical sutures, epicardial pacing wires, or pleural plaques. CT shows a thin-walled or thick-walled mass, often with a hyperdense enhancing rim and a high-attenuation central nidus (Fig. 18). Gossypiboma frequently mimics a pleural-based mass and can demonstrate concentric layers of differing densities, including calcification. Over time, the pleural-based mass may invaginate or become enveloped by the surrounding lung parenchyma, mimicking an intrapulmonary lesion such as abscess or intracavitary fungus ball.
      • Park H.J.
      • Im S.A.
      • Chun H.J.
      • et al.
      Changes in CT appearance of intrathoracic gossypiboma over 10 years.
      • Sheehan R.E.
      • Sheppard M.N.
      • Hansell D.M.
      Retained intrathoracic surgical swab: CT appearances.
      • Suwatanapongched T.
      • Boonkasem S.
      • Sathianpitayakul E.
      • et al.
      Intrathoracic gossypiboma: radiographic and CT findings.
      A spongiform pattern of gas bubbles is characteristic; although this air has been thought to represent trapped gas among fibers, many believe that over time there is also communication with the bronchial tree.
      • Sheehan R.E.
      • Sheppard M.N.
      • Hansell D.M.
      Retained intrathoracic surgical swab: CT appearances.
      • Suwatanapongched T.
      • Boonkasem S.
      • Sathianpitayakul E.
      • et al.
      Intrathoracic gossypiboma: radiographic and CT findings.
      • Kopka L.
      • Fischer U.
      • Gross A.J.
      • et al.
      CT of retained surgical sponges (textilomas): pitfalls in detection and evaluation.
      Figure thumbnail gr18
      Fig. 18Gossypiboma in a 59-year-old man who underwent cardiothoracic surgery 1 year earlier. A round peripheral mass containing serpiginous high density was identified on the preceding chest radiograph. Noncontrast axial CT image in mediastinal window demonstrates the soft-tissue mass, which is slightly heterogeneous and surrounded by left lower lobe parenchyma. Metallic density is embedded within the mass. Surgical gauze was retrieved following reoperation.

      Summary

      Thoracotomy with lung resection can produce challenging imaging appearances. Surgical complications can present in the early or late postoperative period, with morbidity and mortality ranging from benign to catastrophic. In many instances, postoperative complications require urgent intervention. Understanding the imaging appearances of both anticipated postsurgical changes and unexpected complications will improve the timeliness and accuracy of diagnosis.

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