Imaging in Lung Transplantation

Imaging of Lung Transplantation

Lung transplantation is the only curative treatment for end-stage lung disease, which is caused by a wide variety of pathologies and encountered in a diverse range of patients. Potential recipients, as well as donors are carefully evaluated by imaging prior to transplant for contraindications to the transplant. After transplantation, recipients are imaged in the immediate, early, intermediate, and late periods for complications that may arise and require intervention. Radiography and computed tomography are the 2 most commonly used imaging modalities used to evaluate the chest after lung transplantation.

Prevention and Management of Infections in Lung Transplant Recipients

Anti-rejection medications are essential in preventing organ rejection amongst solid organ transplant recipients; however, these agents also cause profound immunosuppression, predisposing lung transplant recipients (LTRs) to infectious complications. The timely management including prevention, diagnosis, and treatment of such infectious complications is vital to prevent significant morbidity and mortality in solid organ transplant recipients and allograft dysfunction. LTRs are inundated with microbes that may be recognized as commensals in hosts with intact immune systems. Bacterial infections are the most common ones, followed by viral pathogens. Indications of a brewing infectious process may be subtle. Hence, the importance of adapting vigilance around isolated hints through symptomatology and signs is pivotal. Signals to suggest an infectious process, such as fever and leukocytosis, may be dampened by immunosuppressive agents. One must also be vigilant about drug interactions of antibiotics and immunosuppressive agents. Treatment of infections can become challenging, as antimicrobials can interact with immunosuppressive agents, and antimicrobial resistance can surge under antimicrobial pressure. Transplant infectious disease physicians work in concert with transplant teams to obtain specimens for diagnostic testing and follow through with source control when possible. This heavily impacts medical decisions and fosters a multidisciplinary approach in management. Furthermore, the reduction of immunosuppression, although it augments the risk of allograft rejection, is as crucial as the initiation of appropriate antimicrobials when it comes to the management of infections.

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.

Reasons for Donor Lungs Unsuitability After Radiographic Selection

OBJECTIVES

Deceased lung donation requires optimum donor care, with lung viability greatly affected by the progress of the disease leading to brain death. In this study, we searched for causes of lung unsuitability for transplant in both primary and secondary evaluations.

MATERIALS AND METHODS

Primary lung evaluations included chest radiography, oxygen challenge test, and donor clinical and history examination. Secondary evaluations for lungs that passed the first step included fiberoptic bronchoscopy and donor-recipient matching.

RESULTS

From 2012 to 2017, there were 1020 potential deceased organ donors in our center. Primary evaluations showed that the most prominent reason for lung donation unsuitability was low oxygen challenge result (n = 433, 42.5%). Other reasons were abnormal chest radiograph (n = 378, 38%), history of heavy smoking and inhaled drugs addiction (n = 112, 11%), prolonged intubation (n = 28, 2.7%), and lung disease history (n = 69, 6.7%). There were 104 (10.1%) potential donors to undergo fiberoptic bronchoscopy for further lung evaluation, with 47 (45.2%) selected for final lung donation. Five lungs (4.8%) with bronchoscopic confirmation for suitability were not retrieved due to lack of instruments and resources. Among the 57 (54.8%) rejected potential lung donations, the greatest factor impacting suitability was observation of purulent secretions in bronchoscopy (n = 24, 23%), evidence of aspiration (n = 10, 9.6%), infiltration (n = 7, 6.7%), and tracheitis.

CONCLUSIONS

The most common cause of lung rejection after primary evaluation is observation of purulent secretions in tracheobronchial tree. Therefore, implementation of appropriate strategies to prevent respiratory infection in the intensive care unit is needed to expand the lung donor pool.

Pre-anaesthetic evaluation of the patient with end-stage lung disease

Lung transplantation is a viable alternative for end-stage lung diseases, which offers good quality of life and survival outcomes for recipients. The aims of pre-assessment for potential lung transplant recipients are to assess fitness for surgery, optimise co-morbidities, commence interventions or investigations, weigh risk-benefit ratio, plan appropriate analgesia and obtain informed consent. The assessment information is gathered from the medical record, patient interview, physical examination and pre-operative tests. A comprehensive workup includes cardiopulmonary evaluation, haematological, biochemical, microbiological and immunological investigations. Most of the evidence regarding lung transplantation is gleaned from retrospective data from single, multi-centre or multinational registries. The lack of good quality evidence means that the guidelines are based on expert consensus.

Imaging of the Lungs in Organ Donors and its Clinical Relevance: A Retrospective Analysis

PURPOSE

The aim of the study was to retrospectively evaluate the diagnostic imaging that potential lung donors undergo, the reader variability of image interpretation and its relevance for donation, and the potential information gained from imaging studies not primarily intended for lung evaluation but partially including them.

MATERIALS AND METHODS

Bedside chest radiography and computed tomography (CT), completely or incompletely including the lungs, of 110 brain-dead potential organ donors in a single institution during 2007 to 2014 were reviewed from a donation perspective. Two chest radiologists in consensus analyzed catheters and cardiovascular, parenchymal, and pleural findings. Clinical reports and study review were compared for substantial differences in findings that could have led to a treatment change, triggered additional examinations such as bronchoscopy, or were considered important for donation.

RESULTS

Among 136 bedside chest radiographs, no differences between clinical reports and study reviews were found in 37 (27%), minor differences were found in 28 (21%), and substantial differences were found in 71 (52%) examinations (P<0.0001). In 31 of 42 (74%) complete or incomplete CT examinations, 50 of 74 findings with relevance for lung donation were not primarily reported (P<0.0001).

CONCLUSIONS

The majority of donor patients undergo only chest radiography. A targeted imaging review of abnormalities affecting the decision to use donor lungs may be useful in the preoperative stage. With a targeted list, substantial changes were made from initial clinical interpretations. CT can provide valuable information on donor lung pathology, even if the lungs are only partially imaged.