14th September 2020

A 50-year-old female with no significant past medical history presents with muscle aches

A 50-year-old female with no significant past medical history presents with muscle aches and complains of difficulty standing up from sitting. On physical examination, she was noted to have weakness in his proximal muscles. Her creatine kinase level is elevated. An autoimmune screen reveals positive anti-Jo1 antibodies. 

Which of the following is the most important next investigation?

Select the SINGLE most appropriate option from the list below. Select ONE option only.