Exploratory Muscle Biopsy Assessment Study in Patients With Late-Onset Pompe Disease Treated With Alglucosidase Alfa

Glycogen Distribution

Time frame: Baseline, Week 26

Muscle Fiber Morphology

Time frame: Baseline, Week 26

Lysosomal Inclusions

Time frame: Baseline, Week 26

Percent Change From Baseline in Muscle Involvement Using Mercuri Scoring at Week 26

Muscle involvement was assessed by T1-weighted magnetic resonance imaging (MRI). T1-weighted MRI data was analyzed using the Mercuri scoring in both legs (Total score = 1-4; where 1=Normal appearance, 2=Mild involvement, 3=Moderate involvement, and 4=Severe involvement). For each participants, the average for each the upper (thigh) and lower leg was computed for Mercuri grading.

Time frame: Baseline, Week 26

Percent Change From Baseline in Degree of Fatty Infiltration Using 3-Point 3-Dimensional (3D) Dixon at Week 26

Degree of Fatty Infiltration was assessed by 3-point 3D Dixon acquisition using skeletal muscle MRI in a subset of participants.

Time frame: Baseline, Week 26

Percent Change From Baseline in Disease Activity Using T2 Magnetic Resonance Imaging (MRI) at Week 26

Disease activity (inflammation and/or water content within muscles) was quantitatively assessed by T2 MRI values in a subset of participants. A T2 MRI value of greater than (\>) 39 millisecond (ms) was defined as abnormal. T2 estimation normally requires an additional acquisition for computing the B1 spatial deviation however, can still be estimated if this acquisition is missing.

Time frame: Baseline, Week 26