MDCT evaluation of central airway and vascular complications of lung transplantation

Pulmonary transplant complications: a radiologic review

Lung transplantation has become the definitive treatment for end stage respiratory disease. Numbers and survival rates have increased over the past decade, with transplant recipients living longer and with greater comorbidities, resulting in greater complexity of care. Common and uncommon complications that occur in the immediate, early, intermediate, and late periods can have significant impact on the course of the transplant. Fortunately, advancements in surgery, medical care, and imaging as well as other diagnostics work to prevent, identify, and manage complications that would otherwise have a negative impact on survivability. This review will focus on contextualizing complications both categorically and chronologically, with highlights of specific imaging and clinical features in order to inform both radiologists and clinicians involved in post-transplant care.

Imaging Evaluation of Airway Complications After Lung Transplant

Airway complications (ACs) after lung transplant remain a challenge and include bronchial dehiscence, bronchial stenosis, tracheobronchomalacia, infections, and bronchial fistulas. The spectrum of complications may coexist along a continuum and can be classified as early (<1 month after transplant) or late (>1 month), and anastomotic or nonanastomotic. Bronchiolitis obliterans is the most common form of chronic lung allograft rejection. Airway compromise is seen in rare instances of lung torsion, and imaging may provide helpful diagnostic clues. Computed tomography (CT) and bronchoscopy play major roles in the diagnosis and treatment of ACs after lung transplant. Chest CT with advanced postprocessing techniques is a valuable tool in evaluating for airways complications, for initial bronchoscopic treatment planning and subsequent posttreatment assessment. Various bronchoscopic treatment options may be explored to maintain airway patency. The goal of this article is to review imaging findings of ACs after lung transplantation, with emphasis on chest CT and bronchoscopic correlation.

Diagnosis and interventions of vascular complications in lung transplant

Though rare, pulmonary vascular complications after lung transplantation carry high morbidity and mortality. Knowledge of the normal and abnormal appearance of lung transplant vasculature is essential for timely and appropriate diagnosis and management of complications. Appropriate selection of surgical and endovascular treatments depend on the availability of expertise and requires a multidisciplinary approach to ensure the best outcomes.

A 46-Year-Old Man With Dyspnea, Hypoxemia, and Radiographic Asymmetry After Redo Bilateral Lung Transplantation

CASE PRESENTATION

A 46-year-old man underwent redo bilateral sequential lung transplantation for rapidly progressive bronchiolitis obliterans syndrome that developed 3.5 years after initial transplantation. In the operating room, he was sedated and intubated with a dual lumen endotracheal tube with subsequent single right-lung ventilation and left allograft implantation. His pulmonary arterial pressure became elevated with reperfusion of the newly implanted left lung, which required initiation of cardiopulmonary bypass to facilitate implantation of the right lung. After implantation and reperfusion of the right lung, the patient was weaned from cardiopulmonary bypass. His chest was closed and he was transferred to the thoracic intensive care unit. On arrival to the intensive care unit, the patient was intubated, sedated, and had an oxygen saturation of 92% on a fraction of inspired oxygen of 100%, positive end-expiratory pressure of 10 cm H₂O, and 20 parts per million of inhaled nitric oxide. He had a Swan-Ganz catheter in the right internal jugular vein that measured a mean pulmonary arterial pressure of 33 mm Hg and a pulmonary arterial systolic pressure of 63 mm Hg, which remained persistently elevated and prompted further diagnostic evaluation.

What can happen after lung transplantation and the importance of the time since transplantation: radiological review of post-transplantation complications

Lung transplantation is the best treatment option in the final stages of diseases such as cystic fibrosis, pulmonary hypertension, chronic obstructive pulmonary disease, or idiopathic pulmonary fibrosis. Better surgical techniques and advances in immunosuppressor treatments have increased survival in lung transplant recipients, making longer follow-up necessary because complications can occur at any time after transplantation. For practical purposes, complications can be classified as early (those that normally occur within two months after transplantation), late (those that normally occur more than two months after transplantation), or time-independent (those that can occur at any time after transplantation). Many complications have nonspecific clinical and radiological manifestations, so the time factor is key to narrow the differential diagnosis. Imaging can guide interventional procedures and can detect complications early. This article aims to describe and illustrate the complications that can occur after lung transplantation from the clinical and radiological viewpoints so that they can be detected as early as possible.

Iatrogenic-related transplant injuries: the role of the interventional radiologist

As advances in surgical techniques and postoperative care continue to improve outcomes, the use of solid organ transplants as a treatment for end-stage organ disease is increasing. With the growing population of transplant patients, there is an increasing need for radiologic diagnosis and minimally invasive procedures for the management of posttransplant complications. Typical complications may be vascular or nonvascular. Vascular complications include arterial stenosis, graft thrombosis, and development of fistulae. Common nonvascular complications consist of leaks, abscess formation, and stricture development. The use of interventional radiology in the management of these problems has led to better graft survival and lower patient morbidity and mortality. An understanding of surgical techniques, postoperative anatomy, radiologic findings, and management options for complications is critical for proficient management of complex transplant cases. This article reviews these factors for kidney, liver, pancreas, islet cell, lung, and small bowel transplants.

Vascular anastomotic complications in lung transplantation: a single institution's experience

OBJECTIVES

Lung transplant recipients were reviewed to compare our early and current experience of vascular complications. Since 1995, we have had a policy of early identification and intervention.

METHODS

We undertook a retrospective review of all adult lung transplants performed at our centre. Patients with pulmonary vascular complications before and after 1995 were identified and reviewed to determine changes in management and outcome.

RESULTS

We identified a total of 13 patients with either pulmonary artery or venous obstruction out of a total of 720 adult lung transplants (1.8%). There were 9 females and 4 males with an age range of 25-64 years. Complications were more common in patients with fibrotic lung disease and involved 15 vascular anastomoses, most commonly the pulmonary arterial anastomosis. Prior to 1995, 5 cases were identified, all postoperatively. In this group, the mean time for identification of the complication was 9.4 (range 4-14) days. Only 1 patient survived to discharge. After 1995, vascular complications were identified intraoperatively in 4 cases and corrected immediately. Four cases were identified postoperatively (at <1-17 days) by a computed tomography pulmonary angiogram. Three were treated surgically within 24 h of diagnosis (using cardiopulmonary bypass with cold preservation). One patient was managed conservatively. Among patients identified after 1995, 5 survived to discharge.

CONCLUSIONS

Though rare, pulmonary vascular complications after lung transplantation carry high mortality. In our opinion, early identification and intervention improves outcome. Intraoperative assessment by pressure gradient measurement and transoesophageal echocardiography is recommended. Despite this, mortality remains high and prevention is better than cure.

Volume visualization: a technical overview with a focus on medical applications

With the increasing availability of high-resolution isotropic three- or four-dimensional medical datasets from sources such as magnetic resonance imaging, computed tomography, and ultrasound, volumetric image visualization techniques have increased in importance. Over the past two decades, a number of new algorithms and improvements have been developed for practical clinical image display. More recently, further efficiencies have been attained by designing and implementing volume-rendering algorithms on graphics processing units (GPUs). In this paper, we review volumetric image visualization pipelines, algorithms, and medical applications. We also illustrate our algorithm implementation and evaluation results, and address the advantages and drawbacks of each algorithm in terms of image quality and efficiency. Within the outlined literature review, we have integrated our research results relating to new visualization, classification, enhancement, and multimodal data dynamic rendering. Finally, we illustrate issues related to modern GPU working pipelines, and their applications in volume visualization domain.

Imaging of mesothelioma

Malignant pleural mesothelioma (MPM) is an asbestos-related neoplasm that originates in pleural mesothelial cells and progresses locally along the pleura until it encases the lungs and mediastinum, ultimately causing death. Imaging plays a crucial role in diagnosis and optimal management. Computed tomography (CT) continues to be the primary and initial imaging modality. Magnetic resonance imaging (MRI) complements CT scan and is superior in determining chest wall and diaphragmatic invasion. FDG18-PET/CT provides anatamo-metabolic information and is superior to both CT and MRI in overall staging and monitoring response to therapy. This chapter will detail the imaging finding of MPM and role of imaging in guiding management.

Nrf2-dependent and -independent responses to nitro-fatty acids in human endothelial cells: identification of heat shock response as the major pathway activated by nitro-oleic acid

Electrophilic fatty acid derivatives, including nitrolinoleic acid and nitro-oleic acid (OA-NO(2)), can mediate anti-inflammatory and pro-survival signaling reactions. The transcription factor Nrf2, activated by electrophilic fatty acids, suppresses redox-sensitive pro-inflammatory gene expression and protects against vascular endothelial oxidative injury. It was therefore postulated that activation of Nrf2 by OA-NO(2) accounts in part for its anti-inflammatory actions, motivating the characterization of Nrf2-dependent and -independent effects of OA-NO(2) on gene expression using genome-wide transcriptional profiling. Control and Nrf2-small interfering RNA-transfected human endothelial cells were treated with vehicle, oleic acid, or OA-NO(2), and differential gene expression profiles were determined. Although OA-NO(2) significantly induced the expression of Nrf2-dependent genes, including heme oxygenase-1 and glutamate-cysteine ligase modifier subunit, the majority of OA-NO(2)-regulated genes were regulated by Nrf2-independent pathways. Moreover, gene set enrichment analysis revealed that the heat shock response is the major pathway activated by OA-NO(2), with robust induction of a number of heat shock genes regulated by the heat shock transcription factor. Inasmuch as the heat shock response mediates anti-inflammatory and cytoprotective actions, this mechanism is proposed to contribute to the protective cell signaling functions of nitro-fatty acids and other electrophilic fatty acid derivatives.