Validity of tissue homogeneity in confocal laser endomicroscopy on the diagnosis of laryngeal and hypopharyngeal squamous cell carcinoma

Abstract

Purpose Confocal laser endomicroscopy (CLE) allows imaging of the laryngeal mucosa in a thousand-fold magnification. This study analyzes differences in tissue homogeneity between healthy mucosa and squamous cell carcinoma (SCC) via CLE. Materials and methods We included five SCC patients with planned total laryngectomy in this study between October 2020 and February 2021. We captured CLE scans of the tumor and healthy mucosa. Analysis of image homogeneity to diagnose SCC was performed by measuring the signal intensity in four regions of interest (ROI) in each frame in a total of 60 sequences. Each sequence was assigned to the corresponding histological pattern, derived from hematoxylin and eosin staining. In addition, we recorded the subjective evaluation of seven investigators regarding tissue homogeneity. Results Out of 3600 images, 1620 (45%) correlated with benign mucosa and 1980 (55%) with SCC. ROIs of benign mucosa and SCC had a mean and standard deviation (SD) of signal intensity of, respectively, 232.1 ± 3.34 and 467.3 ± 9.72 (P < 0.001). The mean SD between the four different ROIs was 39.1 ± 1.03 for benign and 101.5 ± 2.6 for SCC frames (P < 0.001). In addition, homogeneity yielded a sensitivity and specificity of 81.8% and 86.2%, respectively, regarding the investigator-dependent analysis. Conclusions SCC shows a significant tissue inhomogeneity in comparison to the healthy epithelium. The results support this feature’s importance in identifying malignant mucosa areas during CLE examination. However, the examiner-dependent evaluation emphasizes that homogeneity is a sub-criterion that must be considered in a broad context.

Clinical significance of type IV vascularization of laryngeal lesions according to the Ni classification

“…OCT enhances the optical imaging of the entire thickness of epithelium and the basement membrane, which is critical in the assessment of invasiveness ( 28 , 31 ). CLE imaging using fluorescein as a contrast agent allowed the visualization of the tissue architecture at a cellular level with up to x1000 magnification, resulting in additional dimension for healthy mucosa and squamous cell carcinoma differentiation contrast to NBI/IMAGE1 S endoscopy ( 28 , 30 ). They can be especially helpful in the evaluation of non-transparent flat lesions, as leukoplakias or erytroplakias ( 28 , 29 ), but also in assessment of the IPCLs of the normal mucosa and squamous cell carcinoma ( 32 ).…”

“…Based on the appearance of intraepithelial papillary capillary loops (IPCLs) detected by NBI or IMAGE1 S, we can predict the character of epithelial changes and improve detection of laryngeal carcinoma, especially in early stages of the disease (3,10,(22)(23)(24)(25)(26). Other imaging techniques, such as optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE), have also shown promise for the detection of early-stage laryngeal carcinoma (27)(28)(29)(30). The benefit of the method lies in the evaluation of the microarchitecture of the epithelium and lamina propria.…”

Development, Implementation and Application of Confocal Laser Endomicroscopy in Brain, Head and Neck Surgery—A Review

“…White et al first described the applicability of CLE in the head and neck region in 1999 using six healthy control tissue specimens and described its morphological similarity with corresponding H&E-stained microscopic sections [ 54 ]. This first description of CLE imaging in the head and neck area was followed by numerous in vitro [ 55 , 56 , 57 , 58 , 59 , 60 ] and in vivo studies [ 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 ] focusing on the noninvasive detection of head and neck cancer using CLE. Table 2 gives an overview of the most important in vitro and in vivo studies on CLE applications in the head and neck region over the past 23 years.…”

“…From 2016 on, systemically applied fluorescein (i.v. application) was used in nearly all published CLE in vivo studies in the head and neck region and presumably provides the best tissue contrast and quality of generated CLE images [ 81 , 82 , 83 , 84 , 88 , 89 , 90 , 91 ]. Further studies have to show if other fluorescent dyes, e.g., indocyanine green, can potentially enhance tissue contrast even more.…”

“…Nearly all studies confirmed a good correlation between CLE morphology and histology and stated a relevant benefit for the intraoperative evaluation and the surgical management of suspicious mucosal lesions [ 54 , 68 , 72 ]. The most relevant morphological criteria for accurate differentiation between tumor and healthy tissue include tissue homogeneity, cell size, borders and clusters, intraepithelial capillary loops, atypical vessels, and the nucleus/cytoplasm ratio [ 81 , 82 , 89 , 90 , 91 ]. Based on these observations, Sievert et al developed CLE imaging scores assessing different combinations of the aforementioned morphological characteristics for laryngeal, pharyngeal, and oral cavity squamous cell carcinomas [ 81 , 82 , 91 ].…”