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

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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.

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).

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

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

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

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

Fig. 1.11  Combined cheek and nasolabial fold collagen injection. Axial CT image (a) shows soft tissue attenuation within the bilateral malar fat pads (arrows). Axial T2-weighted (b), axial post-contrast T1-weighted (c), and

sagittal T1-weighted (d) MR images in a different patient show bilateral globular collections of collagen-based gel filler (arrows), which have signal characteristics similar to that of water

Fig. 1.12  Polyacrylamide gel polymer treatment for HIV lipoatrophy. Axial T2-weighted (a) and T1-weighted (b) MR images demonstrate encapsulated clusters of material

Fig. 1.13  Combined silicone implant and calcium hydroxyapatite cheek augmentation. Axial CT image shows silicone implants bilaterally (arrows), as well as calcium hydroxyapatite filler (arrowheads) superficial to the right silicone implant

(arrows) with similar signal characteristics to water in the right lower cheek. Gel polymer was previously removed from the contralateral side

Fig. 1.15  Cheek implant abscess. Axial (a) and coronal (b) CT images demonstrate left check subcutaneous fat stranding and overlying skin thickening. The left silicone

implant is surrounded and displaced by fluid and subcutaneous stranding, while the right silicone implant is unremarkable. Bilateral nasolabial fold fillers are also present

Fig. 1.16  Cheek implant osteomyelitis. Coronal CT image (a) shows right cheek skin dimpling overlying a draining sinus (arrow) adjacent to a silicone implant. Axial CT (b) image in the bone window shows sclerotic thickening of the right anterior maxillary wall and zygoma

adjacent to the implant (arrowheads). Post-contrast axial (c) and coronal (d) fat-suppressed T1-weighted MR images show the enhancing draining sinus beneath the external marker

Fig. 1.17  Inflammation. Post-contrast fat-suppressed axial T1-weighted MR image shows diffuse enhancement in the bilateral cheek subcutaneous tissues surrounding the filler material (liquid silicone)

Fig. 1.19  Injectable silicone granulomas. Axial CT image shows several subcentimeter nodular densities in the bilateral nasolabial folds and buccal space fat