Hyaluronic Acid Filler Longevity in the Mid-face: A Review of 33 Magnetic Resonance Imaging Studies.

Background: Recent evidence challenges the conventional belief that hyaluronic acid (HA) fillers have a short lifespan of 3-12 months. This study, using extensive patient data and long-term imaging post-injection, suggests a need to reconsider refilling protocols and underscores the critical role of precise clinical photography for accurate comparisons. Methods: The study enrolled 33 patients who received HA fillers in the mid-face, excluding those with recent injections, permanent fillers, or specific medical histories. Magnetic resonance imaging (MRI) was conducted on 24 asymptomatic and nine edema-concerned patients over 2.5 years. Two blinded radiologists assessed filler presence and longevity based on requested MRI observations. Results: MRI scans confirmed HA presence in all 33 patients, with no complete dissipation observed over a 2-year period post injection. Among them, 21 had not received injections for 2-5 years, 12 for over 5 years, and some for up to 8-15 years. Varying volumes of HA were noted: mild in nine patients, moderate in 13, and severe in 11. The study reported HA longevity of up to 15 years across different products, with a 95% confidence interval of 84.47% ± 4.43%, demonstrating the persistence of cross-linked HA fillers in the mid-face. Conclusions: HA fillers remained detectable for at least 2 years in all 33 patients, with one patient showing filler longevity of up to 15 years. These findings suggest significant implications for filler management practices. Further research with larger cohorts and ongoing imaging follow-up is warranted to fully understand HA filler longevity and optimize clinical protocols.