Clinical and imaging features in lung torsion and description of a novel imaging sign

Imaging Features of Uncommon Entities That Manifest with Torsion

Torsion is the twisting of an object along the axis, and various structures (organs and tumors) in the body can twist. Torsion causes initial lymphatic and venous outflow obstruction, leading to congestive edema, enlargement, venous hemorrhagic infarction, and surrounding edema. It can also cause subsequent arterial obstruction depending on the degree of torsion, leading to ischemia, infarction, necrosis, gangrene, and surrounding inflammation. Therefore, in several cases of torsion, immediate surgical intervention is required to improve blood flow and prevent serious complications. Clinical manifestations of torsion are often nonspecific and can affect individuals of varying ages and sex. Imaging plays an important role in the early diagnosis and management of torsion. Multiple imaging modalities, including US, radiography, CT, and MRI, are used to evaluate torsion, and each modality has its specific characteristics. The imaging findings reflect the pathophysiologic mechanism: a twisted pedicle (whirlpool sign), enlargement of the torsed structures, reduced blood flow, internal heterogeneity, and surrounding reactive changes. The whirlpool sign is a definitive characteristic of torsion. In some cases, despite poor internal enhancement, capsular enhancement is observed on contrast-enhanced CT and MR images and is considered to be associated with preserved capsular arterial flow or capsular neovascularization due to inflammation. Radiologists should be familiar with the pathophysiologic mechanisms, clinical characteristics, and imaging characteristics of torsion in various structures in the body. Since other articles about common organ torsions already exist, the authors of this article focus on the uncommon entities that manifest with torsion. ©RSNA, 2024.

Differentiating Imaging Features of Post-lobectomy Right Middle Lobe Torsion

PURPOSE

The purpose of this study was to identify differences in imaging features between patients with confirmed right middle lobe (RML) torsion compared to those suspected yet without torsion.

MATERIALS AND METHODS

This retrospective study entailing a search of radiology reports from April 1, 2014, to April 15, 2021, resulted in 52 patients with suspected yet without lobar torsion and 4 with confirmed torsion, supplemented by 2 additional cases before the search period for a total of 6 confirmed cases. Four thoracic radiologists (1 an adjudicator) evaluated chest radiographs and computed tomography (CT) examinations, and Fisher exact and Mann-Whitney tests were used to identify any significant differences in imaging features (P<0.05).

RESULTS

A reversed halo sign was more frequent for all readers (P=0.001) in confirmed RML torsion than patients without torsion (83.3% vs. 0% for 3 readers, one the adjudicator). The CT coronal bronchial angle between RML bronchus and bronchus intermedius was larger (P=0.035) in torsion (121.28 degrees) than nontorsion cases (98.26 degrees). Patients with torsion had a higher percentage of ground-glass opacity in the affected lobe (P=0.031). A convex fissure towards the adjacent lobe on CT (P=0.009) and increased lobe volume on CT (P=0.001) occurred more often in confirmed torsion.

CONCLUSION

A reversed halo sign, larger CT coronal bronchial angle, greater proportion of ground-glass opacity, fissural convexity, and larger lobe volume on CT may aid in early recognition of the rare yet highly significant diagnosis of lobar torsion.

Segmental Lung Torsion

The authors report an unusual case of segmental lung torsion detected at CT pulmonary angiography in a patient with dyspnea. This case highlights the importance for clinicians and radiologists to consider and be familiar with the diagnosis of lung torsion, a rare and potentially life-threatening pathologic condition that can be successfully treated with emergent surgery if detected early. Keywords: CT, CT Angiography, Pulmonary, Thorax, Lung, Emergency Radiology Supplemental material is available for this article. © RSNA, 2023.

Imaging Course of Lung Transplantation: From Patient Selection to Postoperative Complications

Lung transplant is increasingly performed for the treatment of end-stage lung disease. As the number of lung transplants and transplant centers continues to rise, radiologists will more frequently participate in the care of patients undergoing lung transplant, both before and after transplant. Potential donors and recipients undergo chest radiography and CT as part of their pretransplant assessment to evaluate for contraindications to transplant and to aid in surgical planning. After transplant, recipients undergo imaging during the postoperative hospitalization and also in the long-term outpatient setting. Radiologists encounter a wide variety of conditions leading to end-stage lung disease and a myriad of posttransplant complications, some of which are unique to lung transplantation. Familiarity with these pathologic conditions, including their imaging findings and their temporal relationship to the transplant, is crucial to accurate radiologic interpretation. Knowledge of the surgical techniques and expected postoperative appearance prevents confusing normal posttransplant imaging findings with complications. A basic understanding of the indications, contraindications, and surgical considerations of lung transplant aids in imaging interpretation and protocoling and also facilitates communication between radiologists and transplant physicians. Despite medical and surgical advances over the past several decades, lung transplant recipients currently have an average posttransplant life expectancy of only 6.7 years. As members of the transplant team, radiologists can help maximize patient survival and hopefully increase posttransplant life expectancy and quality of life in the coming decades. ^©RSNA, 2021 An invited commentary by Bierhals is available online. Online supplemental material is available for this article.

A pictorial review of lung torsion using 3D CT cinematic rendering

Lung torsion is the abnormal rotation of a lobe or lung around its bronchovascular pedicle. It most commonly occurs in the setting of pulmonary resection, though it has also been described after large-volume thoracentesis and video-assisted thoracic surgery, as well as spontaneously. Resulting ischemia can lead to infarction, making this an emergent diagnosis. As findings are often nonspecific, a high index of suspicion is required, especially in the postsurgical setting. 2D CT angiography findings are subtle and include direct signs of pedicle rotation on CT as well as indirect findings including loss of normal parenchymal enhancement, atelectasis of torsed lobe/lung, and abnormal fissure position. These direct and indirect findings are often appreciated on different window presets and upon review of images in multiple planes, with need to collate the information subsequently. 3D cinematic rendering (CR) using multi-planar light sources can readily highlight spatial relationships of vasculature in the chest and may be able to assist in the confident diagnosis of this sometimes subtle but life-threatening pathology. We have provided the first characterization of common lung torsion findings on 3D CR.

Right Upper Lobe Torsion after Right Lower Lobectomy: A Rare and Potentially Life-Threatening Complication

An 84-year-old woman was referred to our institution with suspected right lung cancer. Subsequently, she underwent thoracoscopic right lower lobectomy without mediastinal lymph node dissection. Postoperatively, she complained of dyspnea and developed arterial oxygen desaturation after 12 h and acute respiratory failure (ARF). An emergency chest computed tomography revealed the right upper bronchial stenosis with hilar peribronchovascular soft tissue edema because the middle lung lobe had been pushed upward and forward and the right upper lung lobe had twisted dorsally. Emergency bronchoscopy revealed severe right upper bronchial stenosis with an eccentric rotation and severe edema. The bronchia stenosis was successfully treated with glucocorticoids and noninvasive positive pressure ventilation for ARF.

Spontaneous middle lobe torsion in a patient with multicentric Castleman disease: A case report

We describe a rare case of middle lobe lung torsion in a patient with a tension hydrothorax secondary to multicentric Castleman disease. The case demonstrates the difficulty of diagnosing torsion prospectively, and the possible sequelae of delayed detection. Although imaging features can be confusing, an awareness of this condition and careful image interpretation by radiologists could facilitate early recognition and management of a torted lobe.