Endoscopic narrow-band imaging-quantitative assessment of airway vascularity after lung transplantation

Bronchoscopic assessment of bronchial anastomosis by visualizing local circulation status-index of hemoglobin (IHb) imaging

Background

Healing of airway anastomosis is largely affected by local circulation. Index of hemoglobin (IHb) imaging is a color enhancement technique that clarifies local circulation in the gastrointestinal endoscopic field. In this study, we investigated the relationship between bronchoscopic assessment of bronchial anastomosis using IHb mode and occurrence of anastomosis-related complications.

Methods

IHb was calculated by logarithmic transformation for each pixel of the electronic endoscopic images and expressed by colors of red, green, and blue. The distribution of each color area was automatically calculated by the summation of pixels. A preliminary experiment spraying vasodilator on swine was performed to confirm the relationship between bronchial mucosal circulation and the IHb image. Forty consecutive patients who underwent bronchoplasty were divided into retrospective training and prospective validation cohorts, and anastomosis-related complications and IHb images were analyzed.

Results

The IHb images immediately and accurately reflected the mucosal changes in the animal experiment. Among 25 cases in the retrospective training cohort, 6 cases experienced complications, with significantly lower red and higher blue values in IHb observed (P=0.03 and P=0.01, respectively). A receiver operating characteristic (ROC) curve for IHb red and blue distributions revealed the thresholds to differentiate cases with complications as 89.2 and 109.0, respectively. An analysis of the prospective validation cohort revealed that IHb blue on POD 7 was a potentially reliable predictor of complications, with 60.0% sensitivity and 90.0% specificity.

Conclusions

IHb mode of bronchoscopy may be useful for assessing the local circulatory condition of bronchoplasty, which can predict anastomosis-related morbidity.

Computer-assisted 3D bowel length measurement for quantitative laparoscopy

BACKGROUND

This study aimed at developing and evaluating a tool for computer-assisted 3D bowel length measurement (BMS) to improve objective measurement in minimally invasive surgery. Standardization and quality of surgery as well as its documentation are currently limited by lack of objective intraoperative measurements. To solve this problem, we developed BMS as a clinical application of Quantitative Laparoscopy (QL).

METHODS

BMS processes images from a conventional 3D laparoscope. Computer vision algorithms are used to measure the distance between laparoscopic instruments along a 3D reconstruction of the bowel surface. Preclinical evaluation was performed in phantom, ex vivo porcine, and in vivo porcine models. A bowel length of 70 cm was measured with BMS and compared to a manually obtained ground truth. Afterwards 70 cm of bowel (ground truth) was measured and compared to BMS.

RESULTS

Ground truth was 66.1 ± 2.7 cm (relative error + 5.8%) in phantom, 65.8 ± 2.5 cm (relative error + 6.4%) in ex vivo, and 67.5 ± 6.6 cm (relative error + 3.7%) in in vivo porcine evaluation when 70 cm was measured with BMS. Using 70 cm of bowel, BMS measured 75.0 ± 2.9 cm (relative error + 7.2%) in phantom and 74.4 ± 2.8 cm (relative error + 6.3%) in ex vivo porcine evaluation. After thorough preclinical evaluation, BMS was successfully used in a patient undergoing laparoscopic Roux-en-Y gastric bypass for morbid obesity.

CONCLUSIONS

QL using BMS was shown to be feasible and was successfully translated from studies on phantom, ex vivo, and in vivo porcine bowel to a clinical feasibility study.

Relation between vascular patterns visualized by Narrow Band Imaging (NBI) videobronchoscopy and histological type of lung cancer

Narrow Band Imaging (NBI) videobronchoscopy is a new technique for visualization of microvascular changes in bronchial mucosa. The primary aim of this study was to evaluate relation between vascular patterns visualized by NBI and histology of lung cancer. We prospectively evaluated 65 patients with suspected lung cancer scheduled for bronchoscopy. NBI followed conventional WL videobronchoscopy. After identification of endoscopically visible tumor, NBI was used to determine predominant type of pathological vascular pattern (dotted, tortuous, abrupt-ending blood vessels-Shibuya descriptors). All the lesions were biopsied and histologically confirmed. There were 81.5 % male and 18.5 % female patients evaluated in the study. Lung cancer was confirmed in all patients; 63.1 % were diagnosed with squamous cell lung cancer (SCC), 24.6 % had adenocarcinoma, 9.2 % had small-cell (SCLC) and 3.1 % large-cell lung cancer (LC). Dotted blood vessels were significantly (p < 0.000) associated with adenocarcinoma, identified in 68.4 % adenocarcinoma and 31.6 % SCC. Tortuous blood vessels were identified in 72 % SCC, 8 % adenocarcinoma, 12 % SCLC and 8 % of LC. Tortuous blood vessels were significantly (p < 0.000) associated with SCC. Abrupt-ending vessels were identified in 81 % SCC, 14.3 % SCLC and 4.8 % adenocarcinoma and were significantly associated (p < 0.000) with SCC. Dotted visual pattern of blood vessels identified during NBI videobronchoscopy is highly suggesting adenocarcinoma histology of lung cancer. Tortuous and abrupt-ending blood vessels visualized under NBI videobronchoscopy significantly suggest squamous cell histology of lung cancer. Large-scale studies should be designed in order to determine true relation between visual appearance and histology in lung cancer.

The contribution of airway ischemia and vascular remodelling to the pathophysiology of bronchiolitis obliterans syndrome and chronic lung allograft dysfunction

PURPOSE OF REVIEW

Chronic allograft dysfunction continues to limit the enduring success of lung transplantation. Increasingly it is recognized that events very early post-transplant such as primary graft dysfunction can be linked to poor clinical outcomes at much later time points. In this article we review a number of the different processes that predispose the allograft to ischemia early post-transplant and explore how these events may contribute to obliterative bronchiolitis, the histological correlate of chronic lung allograft dysfunction.

RECENT FINDINGS

Allograft ischemia may arise during explantation (warm ischemia), at implantation (in the absence of bronchial arterial reanastomosis) or at later time points (small airway microvascular damage). We describe how allograft ischemia may result in a hypoxic inflammatory milieu within the lung allograft that is conducive to vascular remodelling and angiogenesis.

SUMMARY

Whilst the published literature for vascular remodelling in post-transplant obliterative bronchiolitis is not as extensive as that for asthma, a disease also characterized by airway pathology, there are clear parallels and shared pathophysiological pathways between the two diseases. An understanding of the complex interaction between ischemia, vascular remodelling and chronic lung allograft dysfunction may lead to the future development of therapeutic strategies that can unravel this association.