Q. A 57-year-old female was admitted yesterday for COVID-19 pneumonia. The patient presented to the emergency department with a 2-day history of fever, dry cough, and shortness of breath. She tested positive for COVID-19 on admission and was diagnosed with pneumonia. She has a past medical history of hypertension and hyperlipidemia, both of which are well controlled on medications. She has never had any previous respiratory illnesses. The patient is a current smoker with a 20-pack-year history. She lives with her husband and has no recent travel history. You are called to evaluate her because a thyroid nodule was incidentally appreciated on her initial assessment. On physical examination today, her temperature is 38.5 degrees Celsius (101.3 degrees Fahrenheit), blood pressure is 150/90 mm Hg, heart rate of 110/min, respiratory rate of 24/min, and her oxygen saturation is 93 percent on room air. Lung exam reveals decreased breath sounds and crackles in the right lower lobe. You examine her neck for any signs of thyroid enlargement or nodules. Inspection reveals a symmetrical neck with no obvious deformities or masses. Palpation reveals a firm, non-tender nodule measuring approximately 1 cm in size in the right lobe of the thyroid. No other nodules are noted. The thyroid is not tender to touch, and you detect no cervical lymphadenopathy. Her trachea is midline, and there is no evidence of thyromegaly or a fixed mass. The patient has no difficulty with neck mobility or swallowing. You order an ultrasound (see image). You also review her laboratory results and determine her thyroid-stimulating hormone level is 2.0 mIU/L, and her free thyroxine level is 1.5 ng/dL. Based on the information you have at this point in time, which of the following additional diagnostic tests is LEAST useful in managing this patient?