Ryan K. Meacham

In Vivo Ultrasonic Detection of Polyurea Crosslinked Silica Aerogel Implants

Background Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. Methodology In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Conclusion/significance Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location.

Sialolipoma of the parotid gland: Case report with literature review comparing major and minor salivary gland sialolipomas

Sialolipoma is a rare tumor found within both major and minor salivary glands. Here we discuss sialolipoma of the parotid gland and briefly review the English literature. Including our case, a total of 35 sialolipomas have been reported, 18 within major salivary glands and 17 within minor salivary glands. Major gland sialolipomas most often are presented in the parotid gland (77%) and those from minor glands were most often seen in the palate (41%). All lesions were well circumscribed and contained mature adipose tissue intimately admixed with benign salivary gland components. Ductal dilatation was found in 100% of minor salivary gland sialolipomas but in only 28% of major salivary gland tumors. Nerve entrapment has also rarely been noted in major salivary glands (14%) whereas myxoid degeneration has been identified in rare minor salivary glands tumors (13%). Treatment is surgical excision and is curative with no reports of recurrence.

Ultrasound-Guided Fine-Needle Aspiration of the Tongue Base A Cadaver Feasibility Study

Objective The authors hypothesize that floor-of-mouth and tongue base anatomy can be visualized with ultrasound and that ultrasound can be used to accurately guide needle placement and dye injection into the tongue base, serving as a surrogate for fine-needle aspiration. Study Design Observation of experimental intervention. Setting Medical school cadaver anatomy laboratory. Subjects and Methods Ultrasound imaging was performed on human cadaveric specimens to visualize the anatomy of the floor of mouth and base of tongue in a midline transcervical approach. Methylene blue dye was injected under ultrasound guidance into the base of tongue. Specimens were dissected, and results were counted and analyzed. Results Twenty-five of 32 (78%) cadaver specimens were found to have correct placement of dye within the posterior genioglossus and intrinsic tongue musculature. Seven cadavers did not have correct placement of dye. Of these, 3 had dye staining the walls of the oropharynx and epiglottis. Two specimens had dye injected erroneously into the geniohyoid muscles. One patient was found to have had a partial glossectomy. Difference in neck circumference was not significant between those with correct (mean, 37.9 cm) and incorrect (mean, 37.4 cm) dye placement (P = .75). Conclusion Anatomy of the floor of mouth and tongue base can be readily depicted with ultrasonography. After reasonable success of injecting dye into cadaver tongue bases, the authors conclude that there appears to be a future clinical role for ultrasound-guided fine-needle aspiration of the tongue base for tongue base lesions.

Is obesity truly a risk factor for mortality after tracheotomy

Objectives: We sought to determine the short-term and long-term overall mortality rates in obese and non-obese patients after tracheotomy and to evaluate which factors, including the Charlson Comorbidity Index (CCI), predict mortality rates among obese patients. Methods: We performed a retrospective chart review of patients who underwent open tracheotomy in the operating room at a single hospital from 2005 to 2010. Results: Of 200 patients reviewed, 146 were non-obese and 54 were obese. The rate of mortality was higher at 30 days (p = 0.02) and at 1 year (p = 0.04) in obese patients (35.1% and 59.2%, respectively) than in non-obese patients (19.2% and 42.5%, respectively). The need for tracheotomy due to ventilator-dependent respiratory failure (VDRF) was much higher (p < 0.001) in obese patients (83.3%) than in non-obese patients (56.8%), and the rate of mortality was significantly higher (p < 0.001) in those who required tracheotomy for VDRF (32.8% at 30 days and 57% at 1 year) than in those who required tracheotomy for all other indications (4.2% at 30 days and 25% at 1 year). The mortality risk increased with higher CCI scores at both 30 days (p = 0.08) and 1 year (p = 0.009). Conclusions: The overall mortality rate is higher in obese patients after tracheotomy than in non-obese control subjects in the short and long terms. This increased rate of mortality is due to the heightened incidence of tracheotomy for VDRF among obese patients. The mortality rates after tracheotomy correlate well with the CCI.

Novel Techniques in Head and Neck Ultrasound

Objective: 1) Report new uses of ultrasound within the head and neck. 2) Emphasize how the use of ultrasound can enhance patient management and alter treatment delivery. Method: Present a series of 7 cases from the past year at a single academic institution where ultrasound was used in a novel way to enhance patient care. Compare the ultrasound images obtained with other imaging modalities. Results: Three patients underwent ultrasound-guided fine- needle aspiration (FNA) of tongue base tumors, which avoided the necessity of a tracheotomy in 1 patient with a difficult airway. Two patients underwent ultrasound-guided FNA of supraglottic tumors through the thyrohyoid membrane, which obviated the need for biopsy with general anesthesia. One noncancer patient had a highly metabolic enlarged lymph node on PET/CT though it demonstrated benign characteristics on ultrasound. Both ultrasound-guided FNA and incisional biopsy confirmed the lymph node’s benignity. One patient had a vallecular foreign body seen on ultrasound but not on flexible laryngoscopy, and it was retrieved in the operating room. Conclusion: Ultrasound can be used to guide FNA for tissue diagnosis from tongue base and larynx tumors. Ultrasound-guided FNA may eliminate the need for biopsy under general anesthesia for some patients. Ultrasound has an expanding array of applications and is a useful tool in the otolaryngologist’s hands.

Ultrasound-Guided FNA of Base of Tongue: A Cadaver Study

Objective: 1) Determine the utility of ultrasound imaging to visualize the anatomy of the tongue base. 2) Demonstrate that ultrasound imaging can guide transcervical needle placement in the tongue base and thus serve as a surrogate for needle biopsy in the patient with a tongue base lesion. Method: Design and subjects: Feasibility study of ultrasound-guided needle placement in the tongue base in 37 adult cadavers. Interventions: Ultrasound imaging of tongue base anatomy and guidance of dye injection into the intrinsic muscles. Outcome Measurements: Tongue base anatomy visualization on ultrasound and placement accuracy of dye injection. Results: Of 37 cadaver heads, 32 were noted to have excellent and identifiable anatomy of the geniohyoid, genioglossus, and intrinsic muscles of the tongue base. The intrinsic muscles were well visualized during methylene blue dye injection on most specimens, with confirmation of the needle tip location and “bloom” of the injection on real-time ultrasound images. After bisection, 25 of 32 (78%) evaluable specimens were found to have accurate placement of dye within the posterior genioglossus and intrinsic tongue base muscles. Neck circumference was similar between those with accurate (mean 37.9 cm) and inaccurate (mean, 37.4 cm) dye placement (P = .75). Conclusion: This study utilizes a cadaver model to establish that ultrasound visualization of the tongue base provides excellent anatomic detail and demonstrates feasibility of transcervical ultrasound localization of the tongue base for image-guided FNA. This technique has potential applicability to the clinical setting.