Injectable facial fillers: imaging features, complications, and diagnostic pitfalls at MRI and PET CT

Abstract

Injectable fillers are widely used for facial rejuvenation, correction of disabling volumetric fat loss in HIV-associated facial lipoatrophy, Romberg disease, and post-traumatic facial disfiguring. The purpose of this article is to acquaint the reader with the anatomy of facial fat compartments, as well as with the properties and key imaging features of commonly used facial fillers, filler-related complications, interpretation pitfalls, and dermatologic conditions mimicking filler-related complications. The distribution of facial fillers is characteristic and depends on the anatomy of the superficial fat compartments. Silicone has signature MRI features, calcium hydroxyapatite has characteristic calcifications, whereas other injectable fillers have overlapping imaging features. Most fillers (hyaluronic acid, collagen, and polyalkylimide–polyacrylamide hydrogels) have signal intensity patterns compatible with high water content. On PET-CT, most fillers show physiologic high FDG uptake, which should not be confounded with pathology. Abscess, cellulitis, non-inflammatory nodules, and foreign body granulomas are the most common filler-related complications, and imaging can help in the differential diagnosis. Diffusion weighted imaging helps in detecting a malignant lesion masked by injected facial fillers. Awareness of imaging features of facial fillers and their complications helps to avoid misinterpretation of MRI, and PET-CT scans and facilitates therapeutic decisions in unclear clinical cases.Key points• Facial fillers are common incidental findings on MRI and PET-CT scans. • They have a characteristic appearance and typical anatomic distribution • Although considered as safe, facial filler injections are associated with several complications • As they may mask malignancy, knowledge of typical imaging features is mandatory. • MRI is a problem-solving tool for unclear cases.

Delayed sclerosing granulomatous reaction to dermal filler injection of poly‐hydroxyethyl‐methacrylate suspended in hyaluronic acid: Histochemical and confocal laser scanning microscopical analysis

“…Late complications, instead, may develop over weeks, months, or even years after the injection and may include diffuse chronic inflammation, nodular outgrowth (usually granulomas), late allergic reactions, hypertrophic scars, and telangiectasia . In such instances, patients usually are unable to properly recall which kind of filler was injected.…”

“…On the basis of manufacturers' and some authors' claims, all commonly used injection materials for esthetic correction and different formulations of hyaluronic acid (HA), with or without adjunctive substances, result in no immunogenic reactions or other complications; nevertheless, unexpected, late, or early adverse reactions have been reported . Overall, poly‐hydroxyethyl‐methacrylate (HEMA) suspended in HA can promote the formation of late foreign body granulomas (FBGs) .…”

Seguridad en la aplicación de rellenos faciales. Medicina basada en evidencia

“…• Sintéticos: parafina, silicón, hidroxiapatita de calcio (CHA), polimetilmetacrilato (PMMA), microesferas, hidrogel de poliacrilamida, metacrilato de hidroxietilo/etilo y ácido poli-L-láctico (PLLA), y policaprolactona-1 (PCL-1). 1,2 Otra clasificación genérica los divide en dos clases principales: reversibles e irreversibles. 8 Según las características de la biodegradación, también se dividen en:…”

“…Los rellenos faciales se utilizan para corregir las líneas de expresión, las depresiones congénitas o adquiridas de los tejidos blandos, los defectos postquirúrgicos y para el remplazo de volumen. [1][2][3][4] Éstos se pueden recomendar como tratamiento para pacientes que buscan un rejuvenecimiento no invasivo; sin embargo, conforme más se usan, los eventos adversos aumentan. 5 La Sociedad Americana de Cirujanos Plásticos (ASPS, por sus siglas en inglés) reporta que, en los Estados Unidos de Norteamérica, en 2018, los rellenos faciales fueron utilizados en 810,240 pacientes, 6 lo que hace a este procedimiento no quirúrgico el segundo más frecuente, después de la aplicación de la toxina botulínica.…”

“…5 La Sociedad Americana de Cirujanos Plásticos (ASPS, por sus siglas en inglés) reporta que, en los Estados Unidos de Norteamérica, en 2018, los rellenos faciales fueron utilizados en 810,240 pacientes, 6 lo que hace a este procedimiento no quirúrgico el segundo más frecuente, después de la aplicación de la toxina botulínica. 2…”