Prospective Paired Evaluation of Conventional Versus Structured Magnetic Resonance Imaging Interpretation for Preoperative Assessment of Gluteal Permanent Synthetic Filler Disease

Eligible participants will undergo a standardized pelvic and gluteal MRI before planned filler-removal surgery. The same examination will be interpreted using two prespecified formats: a conventional qualitative report and a structured report that grades involvement of the fat-fascia interface, subcutaneous fat, deep fascia, gluteal muscles, subcrestal, ischial, trochanteric, and pelvic-ring regions, as well as lymphatic and interstitial pathways. The operating surgeon will record a preliminary plan and utility rating after each report. During surgery, actual compartment involvement will be documented using a standardized map and, when available, specimen and histopathologic findings. Paired diagnostic performance, inter-reader agreement, change in surgical planning, and associations with operative complexity will be analyzed.

Inclusion criteria

• Age 18 years or older.
• History of gluteal injection with a permanent or unknown nonresorbable filler.
• Preoperative pelvic/gluteal MRI performed using the study acquisition protocol.
• Planned surgical removal, biopsy, or operative exploration within 90 days after MRI.
• Written informed consent for paired image interpretation and use of operative findings.

Exclusion criteria

• MRI contraindication or nondiagnostic imaging caused by motion or incomplete anatomic coverage.
• Prior extensive gluteal filler removal that prevents mapping of the predefined compartments.
• No operative procedure within 90 days after MRI and therefore no reference-standard assessment.
• Acute life-threatening infection or emergency surgery that prevents completion of the preoperative reporting sequence.
• Inability to provide consent.