Quantitative Evaluation of Native Lung Hyperinflation After Single Lung Transplantation for Emphysema Using Three-Dimensional Computed Tomography Volumetry

Current trends in thoracic surgery

Thoracic surgery has evolved drastically in recent years. Although thoracic surgeons mainly deal with tumorous lesion in the lungs, mediastinum, and pleura, they also perform lung transplantation surgery in patients with end-stage lung disease. Herein, we introduce various major current topics in thoracic surgery. Minimally invasive surgical procedures include robot-assisted thoracic surgery and uniportal video-assisted thoracic surgery. Novel techniques for sublobar resection include virtual-assisted lung mapping, image-guided video-assisted thoracic surgery, and segmentectomy using indocyanine green. Three-dimensional (3D) computed tomography (CT) simulation consists of surgeon-friendly 3D-CT image analysis systems and new-generation, dynamic 3D-CT imaging systems. Updates in cadaveric lung transplantation include use of marginal donors, including donation after circulatory death, and ex vivo lung perfusion for such donors. Topics in living donor lobar lung transplantation include size matching, donor issues, and new surgical techniques. During routine clinical practice, thoracic surgeons encounter various pivotal topics related to thoracic surgery, which are described in this report.

Native lung complications after living-donor lobar lung transplantation

BACKGROUND

Living-donor lobar lung transplantation (LDLLT) is viable for critically ill patients in situations of donor shortage. Because it is sometimes difficult to find 2 ideal living donors with suitable graft sizes, we developed native lung-sparing procedures, including single LDLLT and native upper lobe-sparing LDLLT. This study aimed to investigate native lung complications (NLCs) in native lung-sparing LDLLT.

METHODS

Between April 2002 and March 2019, 92 LDLLTs and 124 cadaveric lung transplantations (CLTs) were performed at the Kyoto University Hospital. Our prospectively maintained database and clinical records were reviewed to compare NLCs among recipients who underwent native lung-sparing LDLLT (n = 21) with those among recipients who underwent single CLT (n = 61).

RESULTS

Among 21 recipients who underwent native lung-sparing LDLLT, 11 NLCs occurred in 8 recipients. No fatal NLC was noted; however, 2 required surgical intervention. Post-transplant survival was not significantly different between native lung-sparing LDLLT recipients with NLCs and those without NLCs. The incidence of NLCs was comparable between native lung-sparing LDLLT recipients and single CLT recipients (8/21 vs 26/61, p = 0.80); however, NLCs occurred significantly later in LDLLT recipients than in CLT recipients (median: 665 vs 181.5 days after transplantation, p = 0.014).

CONCLUSIONS

NLCs after native lung-sparing LDLLT had favorable outcomes. Therefore, native lung-sparing LDLLT is a useful treatment option for severely ill patients who cannot wait for CLT. However, it is important to recognize that NLCs may occur later in LDLLT than in CLT.

Anterior mediastinal tissue volume is correlated with antiacetylcholine receptor antibody level in myasthenia gravis

OBJECTIVES

Extended thymectomy is a treatment option for myasthenia gravis (MG), but the surgical indications are controversial. Pathologic features of the thymus can be used to predict surgical outcomes, but there is no reliable method for evaluating these characteristics preoperatively. The purpose of this study was to determine whether anterior mediastinal tissue volume, as measured via 3-dimensional computed tomography (3DCT) volumetry, correlates with serum anti-acetylcholine receptor antibody (AChRAb) levels in patients undergoing thymectomy for myasthenia gravis. Therefore, we investigated the relationships among anterior mediastinal tissue volume determined by 3DCT volumetry and AChRAb levels.

METHODS

The subjects were 28 patients who underwent extended thymectomy and were enrolled retrospectively. We measured volume of the anterior mediastinum and calculated the volumes of more than -30 Hounsfield units (V_-30) by using 3DCT volumetry and compared them with perioperative AChRAb levels. The significance of their volumes in MG was examined by comparison with 53 patients without MG.

RESULTS

V_-30 values were related to age and were significantly greater in patients with MG than in patients without MG (P < .001). V_-30 values were correlated positively with preoperative AChRAb levels (ρ = 0.505, P = .006) and inversely with the post/preoperative AChRAb ratio (ρ = -0.453, P = .018). The histologic nonadipose tissue ratio was correlated with the V_-30/volume of the anterior mediastinum (ρ = 0.700, P < .001).

CONCLUSIONS

This method for evaluation of the anterior mediastinal tissue volume and AChRAb production may be helpful in establishing a treatment plan for MG.

Three-dimensional image in lung transplantation

Three-dimensional computed tomography (3D-CT) technologies have been developed and, recently, high-speed and high-quality 3D-CT technologies have been introduced to the field of thoracic surgery. The purpose of this manuscript is to demonstrate the clinical application of 3D-CT technologies in lung transplantation. In Japan, because of the severe donor shortage, living-donor lobar lung transplantation (LDLLT) is essential, in addition to cadaveric lung transplantation. In LDLLT, size matching is a grave issue, since ideal size matching between donor and recipient is usually difficult because of the limited population of potential donor. Size matching using pulmonary function test results has been widely used as a gold standard, but anatomical size matching using 3D-CT volumetry data has also been utilized in LDLLT. In donor lobectomy, 3D-CT images provided a variety of information regarding anatomical variation of pulmonary vessels and bronchial trees preoperatively. These images ensure surgical quality and safety, and they also affect surgical procedures for the recipient. 3D-CT images are also utilized in various aspects of postoperative care, such as detection of chronic lung allograft dysfunction and clarification of its subtypes. Furthermore, preoperative 3D-CT simulation is useful in developing and performing a special surgical procedure, such as right-to-left inverted LDLLT. In conclusion, following the introduction of 3D-CT to the field of thoracic surgery, various 3D-CT images and their application to preoperative simulations have been introduced in lung transplantation. In the near future, this technique will become more prevalent, and frequent use by thoracic surgeons will be seen worldwide in daily practice.

Chronic lung allograft dysfunction: evolving practice

PURPOSE OF REVIEW

Chronic lung allograft dysfunction (CLAD) was recently introduced as an overarching term covering different phenotypes of chronic allograft dysfunction, including obstructive CLAD (bronchiolitis obliterans syndrome), restrictive CLAD (restrictive allograft syndrome) and graft dysfunction due to causes not related to chronic rejection. In the present review, we will highlight the latest insights and current controversies regarding the new CLAD terminology, underlying pathophysiologic mechanisms, diagnostic approach and possible treatment options.

RECENT FINDINGS

Different pathophysiological mechanisms are clearly involved in clinically distinct phenotypes of chronic rejection, as is reflected by differences in histology, allograft function and imaging. Therefore, not all CLAD patients may equally benefit from specific therapies.

SUMMARY

The recent introduction of CLAD importantly changed the clinical practice in lung transplant recipients. Given the relative low accuracy of the current diagnostic tools, future research should focus on specific biomarkers, more sensitive pulmonary function parameters and imaging techniques for timely CLAD diagnosis and phenotyping. Personalized or targeted therapeutic options for adequate prevention and treatment of CLAD are required.