Q. A 45-year-old female presents to the emergency department with complaints of right upper quadrant pain. The patient reports the pain began 2 days ago following a family reunion. The pain is described as constant, dull, and exacerbated by meals and deep inspiration. Her past medical history is significant for hypertension, type 2 diabetes mellitus, and hyperlipidemia. She works as a receptionist, smokes 1 pack of cigarettes per day, and occasionally drinks alcohol. On physical examination, she is afebrile, her blood pressure is 140/90 mm Hg, heart rate 80/min, respiratory rate 20/min, and oxygen saturation is 98 percent on room air. The patient is non-toxic appearing. Her cardiopulmonary assessment is unremarkable. Her abdomen is nondistended and has no visible masses. Auscultation reveals normal bowel sounds and no bruits. You ask the patient to inhale deeply and hold her breath, you then palpate the right upper quadrant with your left hand while using your right hand to press in and upward, which causes her significant pain and she briefly stops breathing. Rebound tenderness is also noted. You order an ultrasound of her right upper quadrant (see image). Additionally, you order blood work, which demonstrates a mild leukocytosis, elevated C-reactive protein, bilirubin of 2.5 mg/dl, alkaline phosphatase of 200 U/L, alanine transaminase of 150 U/L, and an aspartate transaminase of 150 U/L. Based on these findings, which of the following diagnostic studies is LEAST indicated at this time?