Which of the following is NOT used to diagnose Giant Cell Arteritis (GCA)?

• A. Temporal artery biopsy
• B. Chest X-ray
• C. ESR
• D. CRP

Answer: (B)

Giant cell arteritis diagnosis relies on detecting inflammation in the affected arteries and the body's inflammatory response. ESR and CRP rise with systemic inflammation and help raise suspicion and track treatment. Temporal artery biopsy provides histologic confirmation, typically showing granulomatous inflammation in the vessel wall, though skip lesions can occur. A chest X-ray does not visualize the arteries involved in GCA or reflect the inflammatory process, so it cannot confirm the diagnosis. It might be used to evaluate other chest conditions or complications, but not to diagnose GCA. For assessing large-vessel involvement, imaging such as ultrasound of the temporal artery or MR/CT angiography and PET-CT is more informative.