31P MR spectroscopic assessment of muscle in patients with myasthenia gravis before and after thymectomy: initial experience.

Purpose: To prospectively assess muscle metabolism in myasthenia gravis (MG) patients before and after thymectomy by using phosphorus 31 (31P) magnetic resonance (MR) spectroscopy.

Materials And Methods: With institutional review board approval and informed consent, resting and dynamic (31)P MR spectroscopy were performed in 14 healthy volunteers (five men, nine women; mean age, 33 years; range, 23-48 years) and 16 MG patients (six men, 10 women; mean age, 37 years; range 18-50 years) before and after thymectomy. Patients were stratified into groups according to the modified Osserman classification: mild-MG group (classes I-IIA) and moderate-to-severe-MG group (classes IIB-IV).