[Advances in endoscopic diagnosis of dysplasia and carcinoma of the larynx]

[Noninvasive imaging using autofluorescence endoscopy: Value for the early detection of laryngeal cancer]

BACKGROUND

Autofluorescence endoscopy is able to delineate malignancy from normal tissue by color change. The objective of the present study was to assess the value of this noninvasive imaging method for the early detection of laryngeal cancer and its precursor lesions.

PATIENTS AND METHODS

In a prospective study, 152 patients with a laryngeal lesion who were undergoing microlaryngoscopy were investigated. Autofluorescence endoscopy was performed after conventional white light endoscopy, just before excisional biopsy was carried out for histologic verification.

RESULTS

In the early detection of laryngeal cancer and its precursor lesions, autofluorescence endoscopy showed a significantly higher sensitivity (98 vs. 88%) and accuracy (97 vs. 90%) than white light endoscopy alone, whereas the specificity (97 vs. 93%) was essentially equal in both methods.

CONCLUSION

Autofluorescence endoscopy qualifies as a simple screening procedure for rapid detection of suspicious lesions and assessment of their horizontal extension. This allows for guided biopsy or tumor resection, and can also be used in oncological follow-up.

[Early recognition of cancerous lesions in the mouth and oropharynx: Automated evaluation of hyperspectral image stacks]

BACKGROUND

Early detection of cancerous lesions is still crucial for a patient's prognosis. Although diagnostic access to the oral cavity and oropharynx is comparably easy, the incidence of resulting disease remains high. This is due to the fact that in many cases, malignity is recognized too late on a purely visual basis. Previously, we discussed the application of hyperspectral imaging for early detection of precancerous and cancerous lesions of the larynx. This time, we evaluate the method in the oral cavity and oropharynx.

MATERIALS AND METHODS

In 85 patients scheduled for endoscopy, hyperspectral imaging was performed. We used a rigid 0-degree endoscope, a light-adjustable monochromator, and a hyperspectral camera. For evaluation of the method, 3 patients were chosen exemplarily. Training sites from physiological and cancerous tissues were marked. Hyperspectral data from 1 patient were used to train a classifier, which was then used for automatic detection of precancerous and cancerous lesions in another 2 patients.

RESULTS

Intraoperative hyperspectral imaging was performed without any problems. Classification showed sensitivities of 61 and 43%, and a specificity of 100%.

CONCLUSION

This proof-of-concept study underscores the high potential of hyperspectral imaging for early recognition of cancer in the mouth and oropharynx. Besides a better prognosis for cancer patients, this approach could lead to higher cost efficiency in the health system.

Narrow Band Imaging

Objectives:

Narrow band imaging (NBI) is supposed to be a technique for a better visualization of vessel structures in superficial tissue as it selects the wavelengths of hemoglobin. It was hypothesized that, in the regular follow-up examination of patients with recurrent laryngeal papillomatosis, NBI enables a better detection of laryngeal papillomatosis in contrast to normal white light endoscopy.

Methods:

Eleven patients, 10 with a known recurrent papillomatosis (8 with a relapse, 2 without) and 1 with a primary diagnosis of papillomatosis, were examined with normal white light and NBI endoscopy. Twenty-six video sequences (11 white, 11 NBI, 4 doubled for validity) were generated and randomly presented to 20 otolaryngologists who rated the videos in terms of lesions seen and number of lesions identified. Results were compared with the histopathologic findings of microlaryngoscopy.

Results:

Detection of papillomatosis and the correct number of lesions identified were more accurate with NBI than with normal white light endoscopy. There was a significantly higher probability of detecting laryngeal papillomata with NBI.

Conclusions:

NBI endoscopy enables a more accurate detection of laryngeal papillomatosis than white light endoscopy.

[Papillomatosis as a criteria for the formation of the group at risk of laryngeal cancer]

The objective of the present study was to determine the incidence of dysplastic pre-neoplastic alterations in the patients presenting with papillomatosis. The results of the clinical, endoscopic, and morphological examination of 42 patients presenting with laryngeal papillomas made it possible to diagnose grade II-III laryngeal cancer in 7 (16.7%) patients. Half of them exhibited pre-neoplastic changes in laryngeal mucosa. The following criteria for the formation of laryngeal cancer risk groups, besides grade II-III epithelial dysplasia, were identified: long (over 12 months) history of papillomatosis, human papilloma virus infection, the history of smoking over 20 years, professional contacts with petroleum, oil, and lubrication materials, and the male gender. An algorithm of observation and treatment for each group of patients differing in the degree of dysplastic changes in laryngeal mucosa was proposed. It is concluded that adequate clinical and endoscopic monitoring of the patients at risk of laryngeal cancer makes it possible to increase the frequency of detection of this condition at the early stages of its development.

Intra-operative application of confocal endomicroscopy using a rigid endoscope

Objective:

To introduce the application of confocal endomicroscopy during microlaryngoscopy, to enable intra-operative evaluation of human laryngeal epithelium.

Methods:

A rigid endoscope was connected to the scanner head of a Heidelberg Retina Tomograph II confocal laser scanning system via an adapter. The endoscope was gently placed on the surface of a vocal fold through a laryngoscope during microlaryngoscopy.

Results:

The application of confocal endomicroscopy using a rigid endoscope enabled technical improvements (i.e. improved image quality, automatic volume scan, and reduced tissue pressure due to the presence of a perforation plate with central hole at the end of the endoscope) which permitted greater sensitivity and improved handling. Confocal endomicroscopy provided good quality, in vivo, en-face images and enabled an assessment of laryngeal epithelium volume.

Conclusion:

This method enables the surgeon to monitor epithelial changes in pre-malignant lesions. The combination of confocal endomicroscopy together with optical coherence tomography (as a complementary technique that provides optical cross-sections) should be further explored in a formal clinicopathological study.

[Endoscopy of the larynx by hyperspectral imaging]

BACKGROUND

Hyperspectral imaging has been proven to be useful in remote earth sensing, e.g., satellite-based classification of vegetation. After modifying it for in vivo evaluation of the larynx using microscopy, we show its adoption for endoscopes.

MATERIALS AND METHODS

In addition to routine microlaryngoscopies under white light inspection, the laryngoscopy was also performed with not only a conventional operation microscope mounted with a tuneable monochromatic light source and a synchronously triggered monochromatic CCD camera (n = 47 patients), but also a similarly modified rigid 0° endoscope (n = 16 patients). Hyperspectral image cubes were obtained between 390 and 680 nm, analyzed using established software tools, and the data using microscope versus endoscope were compared.

RESULTS

Under endoscopy, illumination was more even and sterical resolution appeared unchanged at significantly shorter image acquisition times. Hyperspectral classification delineated areas of altered mucosa without further external information irrespective of whether image cubes were generated with microscopy or endoscopy.

CONCLUSION

Hyperspectral imaging can be transferred not only to micro(laryngo)scopy but also to endoscopy with rigid optics. This opens the way to a variety of clinically relevant anatomical regions (e.g., upper aerodigestive tract). Its adoption to flexible optics will further broaden this spectrum.

Transoral treatment strategies for head and neck tumors

The introduction of transoral endoscopic surgery has initiated a fundamental change in the treatment of head and neck cancer. The endoscopic approach minimizes the intraoperative trauma. Due to the lower burden for the patient and the savings potential these methods have gained wide acceptance. These transoral accesses routes allow experienced surgeons to reduce the morbidity of surgical resection with no deterioration of oncologic results. This suggests a further extension of the indication spectrum and a high growth potential for these techniques and equipment in the coming years. For selected patients with selected tumors the minimally invasive transoral surgery offers improved oncological and functional results. In the present paper, different surgical access routes are presented and their indications discussed.