REVIEWARTICLE

Aesthetic surgery of the buttocks: imaging appearance

Susan J. Frank & Milana Flusberg & Shari Friedman &

Michael Sternschein & Ellen L. Wolf & Marjorie W. Stein

Received: 19 July 2013 /Revised: 25 September 2013 /Accepted: 7 October 2013 /Published online: 16 November 2013# ISS 2013

Abstract Familiarity with the imaging appearance and po-tential complications of buttocks aesthetic surgery is impor-tant for radiologists. In this review, we illustrate the spectrumof imaging features after buttocks implants, liposuction, fatinjections and silicone injections. Complications such as fatnecrosis, abscess, and silicone migration are also presented.

Keywords Cosmetic . Buttocks . Silicone

Introduction

Aesthetic surgery of the buttocks is increasing in popularity[1]. Reasons for this include heightened attention to exerciseand physical fitness, the popularity of the “thong style” ofwomen’s undergarments and bathing suits [2], and the grow-ing popularity of bariatric surgery with concomitant demandfor body contouring procedures. The aesthetic ideal of thebuttocks varies depending on culture and ethnicity, in partaccounting for the difference in frequency of this surgerythroughout the world [1].

Aesthetic surgery of the buttocks involves reshaping,lifting, and/or augmentation to create larger, firmer, rounder,and more defined buttocks. Various techniques may be used,including liposuction, fat grafting, surgical lifts, implants, andinjection of silicone-based substances. All of these techniques,

with the notable exception of silicone injections, are accept-able and legal in the USAwhen performed by licensed med-ical professionals. However, injections of various forms ofsilicone, which may be impure, are administered outside theUSA or illegally inside the USA, and can result in seriouscomplications.

Recognition of the imaging findings following buttocksinjections can be helpful to clinicians, since it may be difficultto obtain a history of silicone injections, especially if per-formed illicitly. In this paper, we will present the imagingfindings following aesthetic surgery of the buttocks usingimplants, liposuction, fat grafting, and silicone injections.

Buttocks implants

Implant insertion is the most frequently accepted methodworldwide for buttocks augmentation [3]. In the past, siliconegel breast implants were used, but this type of implant is nolonger recommended owing to high complication rates, in-cluding malposition and rupture with leakage of silicone [4].On CT, they appear identical to silicone gel breast implants,visualized as well defined, elliptical, encapsulated, fluid den-sity structures with a hyperdense border. Peri-implant fluid israrely seen more than 1 year after breast augmentation withimplants (0.1 % patients) [5]. The presence of periprostheticfluid with capsular infolding on CT may suggest the presenceof leakage in breast implants [6] and perhaps in buttocksimplants as well (Fig. 1).

Currently, solid/semi-solid silicone implants are the onlyimplants approved by the FDA for use in the buttocks in theUSA. Solid/semi-solid silicone implants are easily identifiedon CT as well-circumscribed, elliptical, hyperdense structures(Fig. 2). They can be inserted into the intramuscular,submuscular, subfascial, or subcutaneous space [7–9]. Thesubcutaneous location is no longer used owing to the high

S. J. Frank :M. Flusberg (*) : S. Friedman : E. L. Wolf :M. W. SteinDepartment of Radiology, Montefiore Medical Center,Albert Einstein College of Medicine, 111 East 210th Street,Bronx, NY 10467, USAe-mail: mflusberg@gmail.com

M. SternscheinRidgewood Plastic Surgery Center, 1200 East RidgewoodAvenue, Ridgewood, NJ 07450, USA

Skeletal Radiol (2014) 43:133–139DOI 10.1007/s00256-013-1753-x

rate of implant visibility, malposition, skin irregularities,seroma, and capsular contracture [8]. Placing the implant ina submuscular location (under the gluteus muscles) is rarelyused today because of potential intra-operative damage to thesciatic nerve or late post-operative neuropraxia due to implantpressure on the sciatic nerve [10]. Subfascial placement re-quires a textured implant, which is not approved for use in theUSA. Intramuscular placement of the implant, in a planecreated within the fibers of the gluteus muscle, is becomingmore popular. An attempt is made to leave 2–3 cm of muscleabove and below the implant. This significantly decreases therisk of sciatic nerve problems.

Although implant rupture is not an issue with solid im-plants, other complications can be significant and can occurwith implant placement in any anatomical space. Peri-prosthetic fluid has been reported in 2–4 % of patients afterintramuscular or submuscular implants [10], and is not con-sidered clinically significant in small amounts in the earlypost-operative period. The most common complication iswound dehiscence, with or without implant exposure, whichcan be seen in up to 30% of cases [11]. A skin defect would bevisualized on CT if this occurred. The use of bilateralparasacral incisions instead of a single midline incision has

decreased this risk. Other complications include hematoma,seroma (3 %), infection (1 %), implant malposition, andcapsular contracture (1–2 %) [7, 9]. The appearance of hema-tomas on CT encompasses a spectrum of findings dependingon chronicity, and varies from hyperdense to complex tocystic. They are usually smoothly marginated and non-enhancing. Seromas are generally smoothly marginated,

Fig. 1 A 45-year-old woman post-buttocks augmentation. Axial non-contrast CT demonstrates bilateral subcutaneous silicone gel implants inthe buttocks (asterisks). Note the presence of fluid surrounding theimplants, more prominent on the left (arrow), and the scalloped contoursuggesting implant leakage

Fig. 2 A 54-year-old woman with a buttock “mass.“ Axial non-contrastCT demonstrates elliptical hyperdense structures in the subcutaneoustissues of the buttocks (asterisks) consistent with implants. Note the fluidcollection around the left implant (arrow)

Fig. 3 A 24-year-old woman post-abdominoplasty and liposuction. Ax-ial contrast-enhanced CT demonstrates a thick, horizontal, linear densityin the posterior soft tissues (arrow) presumably due to the liposuctioncannula tracts. Anterior abdominal wall stranding and bunched-up rectusmuscles following abdominoplasty are also seen (curved arrow). Notethe punctuate high attenuation foci within the rectus muscles correspond-ing to normal perforating vessels

Fig. 4 Illustration of the posterior part of a body lift procedure. Excisionof skin and fat (hatched area) followed by re-approximation and eleva-tion of remaining tissues

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hypodense, and non-enhancing on CT, although they mayappear complex. Capsular contracture is identified on physicalexamination, and usually has no CT equivalent, unless it issevere, when there may be distortion of the implant or mal-position visualized on imaging.

Implants should be removed if there is infection, exposureor leakage/rupture (gel implants). In most cases, the implantscan be replaced after a suitable waiting period, usually 3 to6 months. When patients have chronic, unremitting sciaticneuropraxia, consideration should be given to implant remov-al, particularly if the implant is in the submuscular plane.Implants may also need to be removed for cosmetic reasons,including visibility, malposition, or capsular contracture. Inthis case, the implant is usually replaced immediately.Seromas should be drained and the fluid sent for culture andcytology. Late seromas around breast implants may rarely beassociated with an unusual low-grade malignancy, anaplasticlarge cell lymphoma (ALCL). Although we know of noreports of ALCL related to buttock implants, it would seemprudent to send any late seroma fluid for cytologicalexamination.

Liposuction of the buttocks

Liposuction is the most popular overall body contouring tech-nique used today. Liposuction can be performed alone and/or

in combination with implants and fat injections to enhance theshape of the gluteal region [12, 13]. It is commonly used todeepen and/or elevate the buttocks crease. When performingliposuction, multiple strokes are made with the suction can-nula to remove unwanted fat. On CT, a thick linear densityparallel to the skin surface may be seen, which is likely due tothe cannula tracts (Fig. 3). Complications include seroma,hematoma or infection. Seroma is most common, but stillinfrequent.

Surgical lifts

Thigh and buttocks lifts with incisions in the groin area onlyare still performed today, but are becoming less common. Abelt lipectomy, or body lift, with circumferential incisionshorizontally and above the buttocks is a surgical procedurethat involves removal of redundant skin and fat with elevationand recontouring of the remaining tissue (Fig. 4). This proce-dure has become more common, in part because of the recentincrease in bariatric procedures leading to massive weight lossand resultant excess skin and tissue ptosis. We have not seenCT scans performed following these procedures, but wewould expect the imaging findings to show non-specificpost-operative changes, in the absence of complications.

Fig. 6 A 24-year-old woman post-buttocks fat injections. Axial con-trast-enhanced CT demonstrates multiple soft tissue nodules corre-sponding to sites of injected fat. An encapsulated fat and fluid collec-tion in the left gluteal subcutaneous tissues (arrow ) was shown to bean abscess at aspiration

Fig. 7 A 41-year-old woman with abdominal pain. Axial contrast-en-hanced CT demonstrates linear infiltration of the buttocks (arrow) andnodular densities in the ischiorectal fossae (arrowheads) likely secondaryto migration of injected material

Fig. 8 A 60-year-old woman with abdominal pain. Axial contrast-enhanced CT demonstrates a predominantly nodular pattern in thebuttocks (arrow )

Fig. 5 A 49-year-old woman with abdominal pain. Axial contrast-en-hanced CT demonstrates multiple foci of chronic fat necrosis (arrow) inthe buttocks after presumed fat injections

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Complications include seroma, hematoma, infection, andwound dehiscence [10, 14].

Fat injections

Fat injections are most commonly used in the face, but largevolume injections in other areas are becoming more accepted.

The fat cell survival rate of fat transplantation has significantlyincreased in the last 10 years. This is largely due to newertechniques of fat preparation and transfer, called “structural”or “micro fat grafting,” popularized by Coleman [15]. In thistechnique, the fat is carefully suctioned from the donor site

Fig. 9 A 33-year-old woman post-buttocks fat injections. Axial contrast-enhanced CT demonstrates intramuscular fat due to intramuscular injec-tions (arrow)

Fig. 10 A 31-year-old woman status post-buttocks fat injections, per-formed in the Dominican Republic. a Axial T2-weighted image withoutfat saturation demonstrates multiple nodules (arrow) in the buttocks withsimilar signal intensity to the subcutaneous fat. b Axial T2-weightedimage with fat saturation demonstrates marked signal loss in the nodules(arrow), confirming the presence of fat

Fig. 11 A 35-year-old male-to-female transsexual presenting with cellu-litis after the injection of a presumed silicone-based substance. Axial non-contrast CT demonstrates an extensive confluent pattern with associatedhyperdensities, complicated by large ulcerations (asterisks). a Note mi-gration of the injected substance into a right hypogastric lymph node(arrow). b Migration of the injected substance anterior to the piriformismuscles (arrow). c Scout image from CT demonstrating extensive softtissue densities and ulcerations (arrow ). Note the pronounced hipcontouring

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and then processed to remove all materials except the fat cells.Small amounts of fat cells are then injected into the subcuta-neous tissue of the face. When used for buttocks augmenta-tion, larger amounts (1500 to 3000 cc) of fat are harvestedfrom many areas, including the abdomen, flanks, hips, and/orthighs. Typically, 500 to 1,000 cc of processed fat is injectedinto each buttock. Multiple passes are needed to inject asignificant volume, and the fat grafts are deposited in allanatomical layers, starting from just superficial to the perios-teum and continuing all the way to the subcutaneous tissue.Large clumps of transferred fat should be avoided, as this canlead to decreased graft survival and fat necrosis (Fig. 5) [10].

On CT, fat injections may appear as soft tissue infiltrationand/or non-specific soft tissue density nodules in the buttocks(Fig. 6). An infiltrative pattern may be seen as a diffuse hazysoft tissue density replacing the normal subcutaneous fat(Fig. 7). A nodular pattern may also be visualized with innu-merable, well-defined rounded soft tissue densities (Fig. 8).The appearance may be similar to fat necrosis; however, thedistribution and extent of the process, especially if there is aknown history of fat injections, helps to make the distinction.When fat is injected directly into the gluteus muscle, it may bevisualized on CT as linear or globular areas of fat densityinterdigitating between muscle fibers (Fig. 9). On MRI, fatinjections can be recognized as nodules that lose signal afterfat saturation (Fig. 10).

Even with structural fat or micro-fat grafting, there iscommonly a small amount of fat necrosis, which may resultin late calcifications, which has been observed and studiedafter fat injections in the breast [16]. Other complications offat injection include poor graft survival, cellulitis, abscess,seroma, and hematoma [2]. On CT, cellulitis appears as infil-tration of the subcutaneous tissues, often with associated skinthickening. The CT appearance of an abscess is a hypodense,well-defined structure, often with a thick, enhancing rim(Fig. 6), which may contain gas.

Silicone injections

There has been controversy about the safety of liquid siliconeinjections into the body for over 50 years. Many claim thatwhen “medical grade” silicone is used by well-trained healthcare professionals, the results are excellent and permanent.However, even under ideal conditions and with the use of“medical grade “silicone, complications can occur years later,including granuloma formation, chronic inflammation, andextrusion or movement of silicone. In 1994, a “purified,injectable grade” silicone received FDA approval to treatretinal detachment. Because this form of silicone has FDAapproval, it has been used in the USA for soft tissue augmen-tation under “off label regulations.” Although large amountswould be required, theoretically it could be used for buttocksaugmentation.

Unfortunately, there are untrained, unlicensed individualsinjecting impure, “industrial grade” silicone into the buttocksand other anatomical areas. In addition to the impurities, thesesilicone liquids may not be sterile. Complications are morecommon with industrial, impure or adulterated silicone andwith large volume injections of silicone [17]. Local compli-cations include abscess, chronic drainage, cellulitis, and skinerosion [18, 19]. The appearance of abscess and cellulitis aresimilar to the complications when fat injections have beenperformed. Ulcerations are visualized on CT as soft tissuedefects with skin thickening and may be associated with gas(Fig. 11).

Since silicone permanently resides in the tissues, surgicalremoval may be the only way to treat these chronic problems.Surgical removal of silicone may be very difficult and can bedisfiguring. Pre-operative MRI is essential to localize thesilicone to facilitate identification and removal by the surgeon.

Free silicone, particularly “industrial grade,” can migratealong tissue planes to remote sites and/or gain access to lymphnodes (Fig. 11). Non-specific systemic signs may develop,

Fig. 12 A 60-year-old womanwith abdominal pain. a Lateralview from lumbosacral spineseries demonstrates nodular softtissue densities in the buttocks(arrow). Incidentally, there is avertebral compression fracture. bAP view of the pelvisdemonstrates similar findings(arrows)

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including fever, nausea, and vomiting. Symptoms may bedelayed in some cases for months or years after the procedure.Life-threatening silicone pneumonitis has been reported afterbuttocks injection [20]. By recognizing the imaging appear-ance of injected silicone in the buttocks, the radiologist canfacilitate the connection between the silicone and the variouscomplications.

The imaging appearance of the buttocks after siliconeinjection has only been briefly described [21]. Plain films ofthe abdomen may demonstrate abnormal soft tissue densitiesin the buttocks corresponding to injected radiodense materialor secondary calcifications (Fig. 12).

On CT, silicone injections can be seen as subcutaneousdensities, either ill-defined or well-defined, in an infiltrative,nodular or confluent pattern. A confluent pattern has theappearance of multiple large subcutaneous soft tissue

Fig. 14 A 45-year-old woman with rectal pain. a Axial contrast-en-hanced CT demonstrates nodular and infiltrative changes in the buttocks(asterisks). A thickened linear density parallel to the skin surface (arrow)may be due to fascial thickening or cannula tracts from concomitantliposuction for contouring. b Axial contrast-enhanced CT at an inferiorlevel demonstrates infiltration of the right ischiorectal fossa likely sec-ondary to migration of injected material (arrow)

Fig. 13 A 42-year-old woman presenting for preoperative planning forsilicone removal. Axial non-contrast CT demonstrates the confluent patternwith heterogeneous mass-like density throughout the buttocks (arrow)

Fig. 15 A 46-year-old woman with sciatica. a Sagittal T2-weightedimage demonstrates multiple hyperintense nodules in the posterior softtissues (arrow). b The nodules remain hyperintense on a fat-suppressedimage at the same level (arrow) consistent with silicone. c Sagittal T1-weighted image demonstrates multiple intermediate signal intensity nod-ules in the posterior soft tissues (arrow)

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densities, which appear mass-like (Fig. 13). Densities in theischiorectal fat are sometimes identified on CT. Ischiorectalfossa densities have the same characteristics as the nodules inthe subcutaneous fat, and we hypothesize that they are theresult of lymphatic migration of the injected substanceor movement through tissue planes. Of note, one of ourpatients presented with a complaint of rectal pain andwas found to have infiltration of the perirectal fat inaddition to post-injection changes in the buttocks(Fig. 14).

The appearance of silicone on MRI has been describedextensively in the breast imaging literature, but has receivedlittle attention with respect to the buttocks [22]. In our expe-rience, multiple hyperintense nodules are identified on T2WMRI images, which do not lose signal after fat suppression(Fig. 15). On T1W images, nodules are of variable signalintensity. An MRI with a silicone-specific pulse se-quence may be helpful in defining and localizing theforeign material prior to any surgical attempt to removesilicone [23].

Limitations in CT imaging of buttocks injections

Currently, silicone injections cannot be differentiated from fatinjections on CT, as it is impossible to ascertain the materialsinjected in the majority of our patients. Patients are oftenreticent to admit having had this procedure. When they doconfirm that they have undergone buttock injections,they either do not know what has been injected or havebeen given inadequate or incorrect information, often inlay terms.

However, we have observed both infiltrative and nodularpatterns on CT after both silicone and fat injections.Recognition of these varied appearances by the radiologist,even without specific knowledge of what substance has beeninjected, will provide the referring clinician with valuableinformation.

Conclusions

Soft tissue changes after buttocks augmentation are increas-ingly identified on CT as incidental findings. We have de-scribed the imaging findings after these procedures, includinga variety of CT patterns seen after buttocks injections thatto our knowledge have not been systematically addressedin the literature. The appearance and complications sec-ondary to these procedures must be recognized by theradiologist to facilitate appropriate diagnosis and patientmanagement.

Conflict of interest The authors declare that they have no conflict ofinterest

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