Magnetic-resonance tomography post injection contouring plastic face different type fillers: features of the picture and signal characteristics

Purpose: to study the possibilities of magnetic resonance imaging in characterizing the soft tissues of the face after injection of various types of fillers. Material and methods. A group of 35 patients with a known cosmetic history was analyzed after combined (15) and non-combined (20) injection injections of fillers into various areas of the face. According to the anamnesis, with combined administration, hyaluronic acid (HA) + Ca hydroxyapatite (CaHA) was used in 10 cases, HA + L­polylactic acid (PLA) in 2 cases, HA + PLA + silicone in 1 case, HA + CaHA + silicone in 1 case, in 1 – HA + silicone. With non-combined administration, 16 patients received HA, 2 received Ca hydroxyapatite, one received L-polylactic acid, and one received polyacrylamide gel (PAGE). MRI of facial soft tissues was performed at different times after drug administration: HA – from 1 month. up to 4 years, CaHA – from 7 days to 1 year, PLA – from 1 to 8 months, silicone – 10–20 years, PAGE – after 6 months. The studies were carried out on 1.5 T MRI scanners, using T2-WI, T1-WI, STIR, DWI (b = 1000), T1-FS-WI, 3D-T2-WI sag. The location of the filler was determined, the type of filler was differentiated, and its location in relation to the surrounding structures was assessed. Results. Areas of the HA preparation were characterized by a hyperintense MR signal on T2-weighted images and Stir, isohypointense on T1-WI. Preparations based on CaHA and PLA were determined by isohypointense on T2, T1-WI, isohyperintense on Stir, iso- and isohyperintense on T1-FS-WI signal. Silicone demonstrated isohypointense signal with a hypointense capsule on T2-WI and Stir isointense on T1-WI; PAGE – isohyperintense on T2-WI and Stir, isohypointense on T1-WI with a hypointense capsule on all PIs. HA-based fillers were more clearly visualized on Stir and T2-WI. Preparations based on CaHA and PLA had identical signal characteristics on T2-WI, which made differential diagnosis difficult, but in a number of cases the following signal changes were detected on T1-FS-WI: iso- and isohypointense from CaHA, isohyperintense from PLA. The MRI picture varied depending on the timing, technique of administration and dilution of the drug. Conclusions. MRI allows you to visualize and differentiate the type of filler after injection contouring according to signal characteristics that depend on its chemical composition, timing of administration and mechanisms of biodegradation.