Comparison of Angiolytic Effects Between the 445-nm Blue Laser and 532-nm Pulsed KTP Laser.

OBJECTIVE: This study aimed to compare the selective absorption of the 445-nm Blue laser (BL) and the 532-nm pulsed potassium-titanyl-phosphate (KTP) laser by blood vessels. METHODS: Thirty-six chicken eggs at day 14 of incubation were dissected to expose the chick chorioallantoic membrane (CAM). Third-order vessels of the CAM were identified and irradiated using BL and KTP lasers using various settings at a laser-to-vessel distance of 3 mm using 0.4 mm fiber size. In total, 494 vessels segments were irradiated. Mean (standard deviation) number of irradiations for each setting was 26.0 (4.6), range from 15 to 39. Outcome measures included ablation rate (AR) and rupture rate (RR). RESULTS: The two lasers were compared for AR and RR at long and medium pulse width (PW) associated with different power levels. At long PW (above 100 ms), BL showed significantly higher AR than KTP at high energy (600 mJ/pulse) and low energy (400 mJ/pulse); they did not show different AR and RR at medium energy levels (500 mJ/pulse). Using medium PW settings plus high and medium energy levels, BL and KTP showed relatively high AR and did not significantly differ in performance. However, at medium PW plus low energy (400-450 mJ/pulse), KTP showed significantly higher AR compared to BL. CONCLUSION: At long PW, BL appeared to show higher AR than KTP at high or low energy levels, but they showed equivalent performance at medium energy. At medium PW, both performed similarly from high to medium energy, but KTP appeared to perform better than BL at lower energy settings. LEVEL OF EVIDENCE: NA Laryngoscope, 134:3220-3225, 2024.

Effects of 445-nm Laser on Vessels of Chick Chorioallantoic Membrane with Implications to Microlaryngeal Laser Surgery.

OBJECTIVE: Previous research has shown that effective application of angiolytic lasers in microlaryngeal surgery is determined by wavelength, pulse width (PW), and fluence. Recently, a 445-nm (blue) laser (BL) has been developed with a potentially greater hemoglobin absorption than previous lasers. The chick chorioallantoic membrane (CAM) represents a suitable model for testing various settings to find out the most optimal settings of this laser. This study used the CAM model to examine whether successful photoangiolytic effects could be obtained using BL. METHODS: Seven hundred and ninety three third-order vascular segments of viable CAM were irradiated using BL via 400-µm diameter fiber, 1 pulse/second, with PW and power varied systematically at standardized fiber-to-vessel distances of 1 and 3 mm. Outcome measures including vessel ablation rate (AR), rupture rate (RR), and visible tissue effects were analyzed using Chi-square test. RESULTS: Energy levels of 400, 540, and 600 mJ (per pulse) were most effective for vessel ablation. A working distance of 3 mm resulted in higher ablation and less vessel rupture compared with 1 mm at these optimal energy levels. At 3 mm, a longer PW resulted in higher AR. At 1 mm, AR increased with shorter PW and higher power. The 1-mm working distance resulted in lower tissue effects than 3 mm. CONCLUSION: Findings in this study showed that BL was effective in vessel ablation using relevant combination of working distance, PW, and energy levels. To obtain high AR, longer working distance plus longer PW was required and if working distance was reduced, shorter PW should be set. LEVEL OF EVIDENCE: NA Laryngoscope, 131:E1950-E1956, 2021.

Otosclerosis in a nonendemic population: Utility of CT scan and correlation with audiometry and surgical outcome.

The incidence of otosclerosis in nonendemic patients is low, and preoperative diagnosis can be challenging. The aim of this study was to evaluate computed tomography (CT) findings in patients with otosclerosis and determine their correlation with audiometric findings and surgical outcome in a nonendemic population. We retrospectively reviewed 17 patients from August 2011 to August 2013 with surgically confirmed otosclerosis who underwent preoperative high-resolution CT scans and pre- and postoperative audiometry. Otosclerotic foci were identified on the scans. The density ratio of these foci was calculated and compared with pre- and postoperative audiometric parameters. One patient with Paget disease was excluded from the study. A total of 19 ears were operated on and included in the data analysis. CT scans were normal in 4 ears (21.1%). Hypodense lesions were detected in the remaining 15 (78.9%) ears and the region of interest mapped out. The density ratio was obtained between the hypodense area and adjacent normal labyrinthine bone. No statistically significant correlation was found between the density ratio and any of the audiometric parameters tested (p > 0.05). The diagnosis of otosclerosis in nonendemic areas is challenging. A preoperative CT scan can be useful when otosclerotic foci are present. However, the density ratio of the otosclerotic foci did not correlate with audiometric parameters or surgical outcome.

Dual instrument for in vivo and ex vivo OCT imaging in an ENT department.

A dual instrument is assembled to investigate the usefulness of optical coherence tomography (OCT) imaging in an ear, nose and throat (ENT) department. Instrument 1 is dedicated to in vivo laryngeal investigation, based on an endoscope probe head assembled by compounding a miniature transversal flying spot scanning probe with a commercial fiber bundle endoscope. This dual probe head is used to implement a dual channel nasolaryngeal endoscopy-OCT system. The two probe heads are used to provide simultaneously OCT cross section images and en face fiber bundle endoscopic images. Instrument 2 is dedicated to either in vivo imaging of accessible surface skin and mucosal lesions of the scalp, face, neck and oral cavity or ex vivo imaging of the same excised tissues, based on a single OCT channel. This uses a better interface optics in a hand held probe. The two instruments share sequentially, the swept source at 1300 nm, the photo-detector unit and the imaging PC. An aiming red laser is permanently connected to the two instruments. This projects visible light collinearly with the 1300 nm beam and allows pixel correspondence between the en face endoscopy image and the cross section OCT image in Instrument 1, as well as surface guidance in Instrument 2 for the operator. The dual channel instrument was initially tested on phantom models and then on patients with suspect laryngeal lesions in a busy ENT practice. This feasibility study demonstrates the OCT potential of the dual imaging instrument as a useful tool in the testing and translation of OCT technology from the lab to the clinic. Instrument 1 is under investigation as a possible endoscopic screening tool for early laryngeal cancer. Larger size and better quality cross-section OCT images produced by Instrument 2 provide a reference base for comparison and continuing research on imaging freshly excised tissue, as well as in vivo interrogation of more superficial skin and mucosal lesions in the head and neck patient.

Analysing lateral soft tissue neck radiographs.

A lateral soft tissue neck radiograph is a useful adjunct in diagnosing and managing the patient presenting with upper airway symptoms but is often inadequately reviewed. We present some common findings and robust systems to improve analysis of these radiographs.