Imaging of Facial Cosmetic Surgery

and Daniel Thomas Ginat3



(1)
Department of Radiology, Beverly Tower Wilshire, Advanced Imaging, Beverly Hills, CA, USA

(2)
University of Southern California, Keck School of Medicine, Los Angeles, CA, USA

(3)
Department of Radiology, University of Chicago, Pritzker School of Medicine, Chicago, IL, USA

 




1.1 Overview of Facial Cosmetic Materials and Their Imaging Features


A wide variety of materials have been used to augment facial tissues in the form of implants, grafts, fillers, and injectables (Fig. 1.1). The main types of implant and graft materials (Table 1.1) include solid silicone, polytetrafluoroethylene, high-density porous polyethylene, bone, and fat, while the main types of fillers and injectables (Table 1.2) include hyaluronic acid preparations, calcium hydroxyapatite, collagen, polytetrafluoroethylene, silicone, alkyl-imide gel polymer, and botulinum toxin, among others.

On occasion, CT or MRI will be obtained to evaluate complications, which include foreign body granuloma formation, seroma, infection/fistula/draining sinus, skin atrophy, implant migration and extrusion, change in cosmetic result, functional alteration, vision loss, dysesthesia, ossification, and obstructed breathing, among others, depending on the type of implant or graft. Alternatively, changes related to facial surgery may be encountered incidentally on imaging.


1.2 Forehead Augmentation



1.2.1 Discussion


Forehead augmentation is performed for improving the upper facial contour. A variety of alloplastic implants have been used for this purpose, including polytetrafluoroethylene and silicone. Often, silicone implants have corrugated edges and central perforations in order to optimize fixation and prevent capsular contraction. Fillers, such as calcium hydroxyapatite, also have a role in forehead augmentation. These materials can be inserted in the midline (Figs. 1.2 and 1.3), lateral brow (Fig. 1.4), or both. Botox is another minimally invasive option for reducing lines and wrinkles.

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Fig. 1.1
Photographs of various facial implants (ab)



Table 1.1
Implants and grafts




















































Material

Properties and uses

Imaging appearance

Solid silicone

Rubber elastomer used since 1956

CT: variable attenuation, usually more hyperattenuating than soft tissue, but less hyperattenuating than bone and best discerned using bone windows

Well-tolerated

MRI: very low signal intensity on T1- and T2-weighted sequences

Indications: chin, lateral jaw, cheek, and nose augmentation
 

Polytetrafluoroethylene

Long-lasting, but can be removed surgically

CT: higher attenuation relative to soft tissues, but lower attenuation than bone

Indications: lower face-lift, nasal, and forehead augmentation

MRI: hypointense to fat on T1- and T2-weighted sequences

High-density porous polyethylene

Inert and biocompatible

CT: attenuation between fat and water

Low complication rate

MRI: hypointense to fat on T1- and T2-weighted sequences

Permanent

Enhancement may occur due to fibrovascular ingrowth

Indications: lower face and nasal augmentation. Also used for orbital and auricular reconstruction
 

Bone

Used more frequently in the past for chin and cheek augmentation, often in the form of “button” implants

CT: same as normal bone elsewhere; cortex and trabecular can be identified unless resorption has occurred

Bone or osteochondral grafts are sometimes used in rhinoplasty

MRI: same as bone elsewhere

Harvest sites include the calvarium and rib
 



Table 1.2
Fillers and injectables












































































Filler material

Properties and uses

Imaging appearance

Liquid silicone

Analogous to intraocular silicone injection, but not currently FDA approved for facial cosmesis

CT: variable attenuation, usually similar to soft tissue density

Permanent agent

MRI: variable signal on T1 and T2 depending on viscosity

Relatively higher risk of granuloma formation, particularly with non-medical grade formulations

Decrease in signal with fat suppression
 
More conspicuous on STIR

Collagen

Naturally occurring protein derived from purified bovine collagen given via a subdermal injection

CT: soft tissue attenuation; subcutaneous fat appears infiltrated

Indications: wrinkles, scars, and lines

Lasts approximately 3–6 months

MRI: same signal intensity as water (hypointense to fat on T1 and hyperintense to fat on T2); occasional minimal peripheral enhancement that can persist up to 2 months

Hyaluronic acid preparations

Injectable gel

CT: water attenuation; subcutaneous fat appears infiltrated

FDA approved

Indications: wrinkles, scars, and lines

Lasts about 6 months and can be removed using hyaluronidase injection

MRI: same signal intensity as water (hypointense to fat on T1 and hyperintense to fat on T2); occasional minimal peripheral enhancement that can persist up to 2 months

Polytetrafluoroethylene

Implanted – not injected

CT: higher attenuation relative to soft tissues

Permanent, threadlike material (not metabolized, but can be removed surgically)

MRI: hypointense to fat on T1- and T2-weighted sequences

Indications: filler in multiple sites (nasolabial folds, lips, glabella)
 

Calcium hydroxyapatite

US FDA approved

CT: high attenuation (generally 280–700 HU) initially; eventually the calcium resorbs, typically incites fibrous tissue formation that may be visible on imaging

Temporary injectable that lasts up to at least 2 years

MRI: similar to bone (hypointense to muscle on T1- and T2-weighted sequences); no enhancement

Indications: wrinkles, lines, scars, and HIV lipoatrophy

PET: can lead to hypermetabolic response

Alkyl-imide gel polymer

Injectable, biocompatible, nontoxic, nonallergenic soft tissue filler

CT: water attenuation masses surrounded by thin collagen capsule

Uses: HIV lipoatrophy and rejuvenation

MRI: same signal intensity as water (hypointense to fat on T1 and hyperintense to fat on T2)

Botulinum toxin

Neurotoxin for the temporary improvement of glabellar lines

CT: nil

Intramuscular injection (corrugator and procerus muscles; 5 sites – 0.1 ml each)

MRI: nil

Maximum effect at 30 days. Lasts up to 6 months
 


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Fig. 1.2
Mid-forehead augmentation with polytetrafluoroethylene. Axial (a) and coronal (b) CT images demonstrate hyperattenuating linear implants in the glabella


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Fig. 1.3
Mid-forehead augmentation with calcium hydroxyapatite. Axial (a), coronal (b), and sagittal (c) CT images demonstrate hyperattenuating linear implants with fuzzy edges, which provide a gentle convex contour to the glabella despite the flat frontal bone. A silicone dorsal nasal implant is also present


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Fig. 1.4
Lateral brow augmentation. Coronal CT image shows collections of calcium hydroxyapatite in the lateral supraorbital areas (arrowheads)


1.3 Cheek and Nasolabial Fold Augmentation



1.3.1 Discussion


Cheek augmentation consists of expanding the malar region, submalar region, or a combination of these, often bilaterally. The procedure is performed for soft tissue enhancement or simply for correcting a deficient or atrophic face, including HIV lipoatrophy. A wide variety of materials have been used for these purposes, including coral implants (Fig. 1.5), silicone rubber implants (Fig. 1.6), injectable silicone (Fig. 1.7), injectable calcium hydroxyapatite (Fig. 1.8), polytetrafluoroethylene strips (Fig. 1.9), hyaluronic acid (Fig. 1.10), collagen (Fig. 1.11), alkyl-imide gel polymer (Fig. 1.12), and combination of materials (Fig. 1.13).

Seromas can be present and appear as simple fluid collections surrounding the implants (Fig. 1.14). Seromas typically resolve spontaneously, unless there is superimposed infection. In such cases, the patient may present with fever and purulent drainage. On imaging, stranding of the subcutaneous fat overlying the implant is often evident (Fig. 1.15). Additional manifestations of implant-associated infections include osteomyelitis and draining sinuses (Fig. 1.16). Other complications depend on the type of material used. In particular, liquid silicone can induce extensive inflammation, which appears as stranding or high T2 signal in the subcutaneous tissues (Fig. 1.17). Furthermore, injected nonmedical-grade silicone has a particular propensity to cause scars and granulomas. These complications can develop many years after injection of the filler. Hypertrophic scars can appear as bands of soft tissue within the subcutaneous fat on CT (Fig. 1.18). Granulomas often appear as subcentimeter rounded or oval foci of variable attenuation on CT (Fig. 1.19). Silicone foreign body granulomas can contain microcalcifications or form eggshell calcifications. Implants, such as silicone rubber, can occasionally erode through the bone (Fig. 1.20) and potentially result in sinusitis. Cheek implantation can sometimes induce heterotopic bone formation (Fig. 1.21). Bone grafts can resorb over time, thereby also diminishing cosmetic effect. Migration of fillers or implants can mimic mass lesions and impair vision (Fig. 1.22).

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Fig. 1.5
Cheek augmentation with coral implants. Axial CT image shows hyperattenuating material overlying the bilateral malar eminences


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Fig. 1.6
Silicone implant cheek augmentation. Axial CT image shows bilateral crescent-shaped hyperattenuating implants (arrow) over the zygomatic and maxillary bones


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Fig. 1.7
Acne scar treatment with silicone oil filler. Axial CT image shows punctate hyperattenuating foci of the filler material (arrow) within the subcutaneous tissues of the left cheek


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Fig. 1.8
Anterior face and nasolabial fold calcium hydroxyapatite injection. There is hypermetabolism at the site of the nasolabial fold fillers (arrows) on 18FDG-PET/CT


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Fig. 1.9
Nasolabial fold polytetrafluoroethylene filler. Axial (a) and coronal (b) CT image shows thin strips of hyperattenuating material in the bilateral nasolabial folds and subcutaneous tissues (arrowheads)


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Fig. 1.10
Nasolabial fold hyaluronic acid augmentation. Coronal STIR (a), T1-weighted (b), and post-contrast fat-suppressed T1-weighted (c) MR images demonstrate streaky material with high T2 signal, as well as mild enhancement

Nov 30, 2017 | Posted by in NEUROLOGICAL IMAGING | Comments Off on Imaging of Facial Cosmetic Surgery
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