Visualization of the Facial Nerve with Ultra-high-Frequency Ultrasound.

Background: Profound variations in facial nerve branching, combined with the severe impact of facial palsy on the patient's quality of life, make surgery in this region challenging. Recent advancements in ultrasound (US) technology, including the improved visualization of small structures, have led to a sharp increase in its medical indications in various medical disciplines. We aimed to prove the feasibility of using ultra-high-frequency (UHF) US to visualize the facial nerve and to guide surgeons during surgery on and around the facial nerve. Methods: A cadaveric study was performed on one hemi-face with a UHF US imaging system and state-of-the-art transducers. Firstly, a transcutaneous US was performed, and the facial nerve branches of interest (zygomatic, buccal, and marginal mandibular branches) were marked using US-guided color-injections of filler mixed with methylene blue. Skin and subcutaneous fat were then removed to simulate the intraoperative field. Secondly, an "intraoperative" US examination was performed, and the same branches were marked by US-guided color-injections of filler mixed with indocyanine green. Anterograde facial nerve dissection was performed, and the distance between the nerve branches and the injected filler was measured. Results: All color-injections (mixed with both methylene blue and indocyanine green) were positioned right next to the nerve branches (<1 mm). The image quality of the US below the skin was observed to be far superior to that of the transcutaneous US. Conclusion: UHF US can be used to visualize the facial nerve with high precision both transcutaneously and intraoperatively (after elevation of the skin flap).

4DCT Differentiation of Parathyroid Adenoma: A Case Report.

We report the case of a 72-year-old patient presenting with recurrent primary hyperparathyroidism after total thyroidectomy and parathyroidectomy with presternal autotransplantation. Methionine-PET-CT proved false-positive and Tc-99m-tetrofosmine imaging false-negative. Using a novel multiphase-4DCT technique we identified an anterior mediastinal nodule demonstrating contrast wash-in and wash-out, suggesting parathyroid adenoma. Traditional 4DCT-protocols obtain fewer phases; therefore, this enhancement pattern might have gone unnoticed. After surgical resection the bloodwork normalized, histopathology confirmed a parathyroid adenoma. Teaching Point: Multiphase 4DCT is a potentially helpful technique for the detection of parathyroid adenomas after total thyroidectomy and parathyroidectomy.