Radiological evaluation of Calcium Hydroxyapatite-based cutaneous fillers

Received on: 22/03/2011
Approved on: 25/04/2011

This study was carried out at the Hospital de
Clínicas de Curitiba, Serviço de Dermatologia
da Universidade Federal do Paraná (UFPR) –
Curitiba (PR), Brazil
Conflicts of interests: none
Financial support: none

Abstract

Introduction: Calcium hydroxyapatite is a radiopaque material that was traditionally used to provide radiologic contrast. It has recently been approved for use in cutaneous filling.
Objectives: To define the radiologic characteristics of Calcium hydroxyapatite and its potential to compromise radiologic evaluations.
Methods: Twelve patients received Calcium hydroxyapatite filler in the malar eminence and had radiography of the face (frontal, lateral, mentum-nasal-plaque (Waters), and Hirtz axial incidence technique) 1-8 weeks after the procedure. The X-rays were examined by two radiologists – one of whom was unaware of the filling procedure.
Results: The Hirtz axial incidence technique demonstrated amorphous radiopaque images in the suprazygomatic soft tissues in all cases, in both evaluations. Radiesse® was not detected using the other techniques, and did not illustrate the filler''''''''s position and symmetry. The evaluation of subjacent osseous structures was not compromised by the material''''''''s presence.
Discussion: Calcium hydroxyapatite can be identified in facial radiography when evaluat- ed using a method that avoids overlapping with adjacent osseous structures. Although it does not impair the osseous evaluation, it is recommended that the radiologist or dentist is noti- fied of the material''''''''s presence.
Conclusion: Cutaneous fillings containing Calcium hydroxyapatite can be identified, although not precisely located, using conventional X-ray.

Keywords: FACE, DURAPATITE, X-RAYS

INTRODUCTION

Cutaneous fillers have been increasingly used during the last decade as a versatile and safe non-surgical alternative for the correction of contours and volumetric augmentation with mul- tiple aesthetic applications. 1 Radiesse® is a cutaneous filler com- pounded by microspheres of calcium hydroxyapatite (CaHA) dispersed in a carrier gel. CaHA is known to have radiopaque properties, and has been used as a radiological contrast for two decades. 2

Some reports and case series demonstrate that convention- al x-ray can occasionally clearly show CaHA that has been applied in facial soft tissue for aesthetic purposes – especially when large volumes are used, for example in the treatment of HIV-related lipodystrophia. 3 CaHA is also identifiable in com- puterized tomography (CT), magnetic resonance imaging (MRI) and in positron emission tomography (PET/CT), when the 2-fluoro 2-dioxi-D-glucose (FDG) is detected in the area that received that filler. 4

This study evaluates the radiological repercussions of using a small volume of CaHA in the restoration of the malar volume for facial rejuvenation.

OBJECTIVE

To evaluate the radiological characteristics of CaHA when applied in small volumes to the soft tissue of the face for aes- thetic reasons, the interference capacity of CaHA in conven- tional x-ray evaluations, and the use of x-ray to evaluate the presence and position of the filler.

METHOD

This observational, qualitative prospective study was approved by the Ethics Committee of the Hospital de Clínicas da Universidade Federal do Paraná (PR), Brazil. Female patients (n = 12) aged 41-73, received 0.05 ml CaHA (Radiesse®,Merz- Biolab, São Paulo, Brazil, ) in the deep dermis and subcutaneous region of the malar eminence for correcting age-related hypotrophy (Figure 1). The patients underwent facial radiogra- phy using frontal, lateral, mentum-nasal-plaque (Waters), and Hirtz axial (Figure 2) incidence techniques, with two penetra- tion intensities. The study complied with good clinical practice rules and the patients signed a term of free and informed con- sent.

Examinations were carried out in intervals of one to eight weeks after the filling procedure. The radiographies were evalu- ated at different time points by two radiologists – one of whom was unaware that the filling procedure had been carried out.

RESULTS

The Hortz''''''''s axial incidence technique demonstrated amorphous radiopaque images projected in the soft parts of each paramedian region of the face, in suprazygomatic position, in sites corresponding to the Radiesse® injection points (Figures 3 and 4). This finding was present in all 12 images when the evaluation was carried out under strong light. The filler was seen more clearly in radiographies with smaller penetration of the x- ray. Similar results were obtained in the evaluation conducted by the radiologist who was unaware of the filler''''''''s presence, who supplied a descriptive report of the finding without suggesting its etiology. Radiesse® was not detected in the lateral, frontal or Waters incidence x-rays.

DISCUSSION

According to the literature, CT is more sensitive to Radiesse®, while x-rays only present positive results when large volumes are used. 3 However, this study suggests that when the correct incidence is used, Radiesse® can be detected by x-ray even in small volumes. In order to choose the best incidence, the physician must know the studied region''''''''s anatomy, the available incidence options and how the relevant images are obtained. For that, the physician can rely on the opinion of a radiologist. CaHA is visible in x-rays with a higher density than that of soft tissue, but lower than that of the cortical and medullar bone 5 (Figures 3 and 4). Therefore it is not usually visible when its image overlaps that of a bone, as happened in the lateral, frontal and Waters (or chin-nasal-plaque) images.

The Hirtz incidence involves the patient lying on their back, with their head in maximum extension and the rays beaming perpendicularly on his/her face in the inferior to supeinvasive type of examination – can assist in that investigation, given that radiopacity is a feature that distinguishes fillers con- taining CaHA from others.

When CaHA is detected in soft tissue, it needs to be dis- tinguished from other entities such as dystrophic or heterotopic calcifications, multiple milliary osteoma cutis, myositis ossificans and foreign bodies. 4,6 Patients who receive fillers with CaHA should be aware that they need to warn their physician or den- tist before an x-ray of the treated site in order to avoid diagnos- tic suspicions that could lead to unnecessary additional exami- nations.

CONCLUSION

When a cutaneous filler containing CaHA microspheres (Radiesse®) is applied in the malar region, it can be recognized in conventional x-ray examinations when Hirtz''''''''s axial inci- dence technique is used. Nevertheless, this technique was proven to be ineffective in determining the position and sym- metry of the filler. Its presence does not impede the diagnosis of osseous fractures in the face – the original purpose of that inci- dence type – given that the filler image does not superpose that of the zygomatic bone.

References

1 . Buck DW, Alam M, Kim JY. Injectable fillers for facial rejuvenation: a review. J Plast Reconstr Aesthet Surg. 2009;62(1):11-8.

2 . Berlin A, Cohen JL, Goldberg DJ. Calcium hydroxylapatite for facial reju venation. Semin Cutan Med Surg. 2006;25(3):132-7.

3 . Carruthers A, Liebeskind M, Carruthers J, Forster BB. Radiographic and computed tomographic studies of calcium hydroxylapatite for treat ment of HIV-associated facial lipoatrophy and correction of nasolabial folds. Dermatol Surg. 2008;34 (Suppl 1):S78-84.

4 . Valiyaparambil J, Rengasamy K, Mallya SM. An unusual soft tissue radiopacity--radiographic appearance of a dermal filler. Br Dent J. 2009;207(5):211-2.

5 . Vazquez J, Rosenthal DI. Bilateral, symmetrical soft tissue calcifications in the face. Skeletal Radiol. 2010;39(4):387-9.

6 . Feeney JN, Fox JJ, Akhurst T.Radiological impact of the use of calcium hydroxylapatite dermal fillers. Clin Radiol. 2009;64(9):897-902.