Prospective Agreement Study of Magnetic Resonance Imaging Measurements and Intraoperative Dimensions During Gluteal Permanent Synthetic Filler Removal

Participants will receive standardized preoperative MRI morphometric mapping within 90 days before surgery. Two trained readers will measure the affected tissue block in three axes, estimate its volume, and record residual flap thickness at predefined surface landmarks. During the index filler-removal procedure, the landmarks will be reproduced and measured directly with a calibrated sterile device. The fresh specimen will be oriented, measured, and weighed before fixation. Agreement, bias, and prediction error will be quantified. Clinical follow-up through day 30 will determine whether thinner flaps or larger prediction errors are associated with ischemia-related wound complications.

Inclusion criteria

• Age 18 years or older.
• Gluteal permanent synthetic filler disease scheduled for elective surgical excision.
• Preoperative MRI performed within 90 days before surgery using the study measurement protocol.
• Planned skin/subcutaneous flap elevation that permits direct thickness measurement at predefined landmarks.
• Written informed consent.

Exclusion criteria

• Emergency surgery or active uncontrolled infection that prevents standardized preoperative imaging or measurement.
• Prior surgery causing loss of the predefined landmarks or making paired measurement impossible.
• Nondiagnostic MRI or incomplete coverage of the planned operative field.
• Specimen fragmentation that prevents standardized fresh-specimen dimension measurement for the secondary endpoint.
• Inability to complete 30-day wound follow-up.