The researchers analyzed the role of synthetic magnetic resonance imaging (MRI) and T2 mapping in differentiating between various types of fillers in soft tissues. In this study, ex vivo fillers of buttock soft tissues (collagen, silicone, and different types of hyaluronic acid) were scanned with a synthetic MRI sequence at 1.5 and 3 T. An optimized T2 mapping sequence was used to measure T2 relaxation times of the fillers ex vivo. Three patients addressed to assess complications with buttock fillers underwent MRI with the standard morphological sequences and an additional synthetic MRI sequence. T2 mapping was not performed for these patients. Two patients had silicone fillers, and the exact filler composition was not knownfor the third patient. Measurements of T1 and T2 relaxation times of ex vivo fillers at 1.5 and 3 T using synthetic MRI demonstrated that collagen, silicone, and hyaluronic acid had distinct relaxation time features. In vivo, the synthetic MRI correctly determined silicone in two patients with known silicone fillers, showing low T1 and T2 values. On the other hand, the synthetic MRI suggested a collagen filler with intermediate relaxation time valuesin the third patient with an unknown filler type.Thus, it was stated that quantitative sequences have the potential to distinguish between types of fillers in a non-invasive manner.

Source: Skeletal Radiol. 2021 Jan;50(1):231-237.