These results show that facially oriented MRI with contrast is a reliable tool to
accurately locate fillers, and identify unintended outcomes such as migration, abscess
formation, granuloma, and delayed allergic reaction. The use of a dedicated facial
MRI with high spatial resolution and elaborate Dixon sequences not only gives the
interpreting radiologist the ability to make a clear-cut decision on the identity
of a substance, but also provides the referring plastic surgeon with a better understanding
of disease pathology and pathophysiology. In addition to its clinical utility, MRI
can provide forensic evidence to medico/legal cases involving injected materials.
Although substances such as silicone and hyaluronic acid have distinct MRI signatures
because of their very high or low water content (Fig. 1), intermediate substances tend to produce a more ambiguous image. T1 and T2 Dixon
fat suppression with high resolution small FOV MRI make it possible to better visualize
and identify these substances (i.e., collagen, Fig. 2). Our original algorithm as summarized in Table 1 which differentiates common fillers in terms of their MRI characteristics, provides
a simple guide to assist radiologists in their analysis.
Fig. 1. Polyacrylamide gel axial dermal filler appearance in both infraorbital triangles (open arrows) on axial MRI (T1FS, T1 FS with gadolinium). Note the susceptibility artifacts from
dental implants (open arrowhead) while the filler’s signal intensity remains high before and after injection of gadolinium
Fig. 2. Collagen dermal filler in both infraorbital triangles (open arrows) on axial MRI (T2FS, T1, T1FS, T1FS with gadolinium)
Dermal fillers are regulated by the Food and Drug Administration in the US, but are
only considered medical devices in the UK and elsewhere 11]. Beauticians and other unlicensed individuals can legally administer dermal fillers
12], and the records of these procedures may be unreliable or even nonexistent. Online
vendors sell products that may be counterfeit or expired, and therefore of dubious
quality 13]. In this risky marketplace, MRI can serve a role both medically and legally (an example
of a “dubious” injection discovered to be silicone in Fig. 3).
Fig. 3. Silicone dermal filler in the right infraorbital triangle (open arrow) as seen on axial MRI (T1, T1FS with gadolinium, T2FS). Note how the free silicone
oil drops behave like fat on MRI, including a intermediate to low signal on fat suppressed
sequences
For example, when a patient is unsatisfied with the result of a cosmetic injectable
filling procedure, MRI could be used to provide an objective evaluation of fullness
and symmetry. While scarring, which demonstrates a low signal on T1 weighted images
and directly impacts the symmetry of dermal fillers, it does not hamper the correct
identification of substance or the radiologist’s ability to assess the distribution
of substance. If overfilling is confirmed (Fig. 4), and hyaluronic acid is determined to be the culprit, a simple injection of hyaluronidase
can reverse the unwanted outcome 14]. In cases of complications involving an unknown product, imaging can help to establish
the identity and guide the approach to treatment. When a granuloma arises from permanent
filler (Fig. 5), treatment may require administration of 5-fluoruracil or allopurinol; otherwise,
steroids and imiquimod may be used 15], 16]. This further underscores the importance of identification of the precise substance
prior to initiating therapy as regards patients’ treatment outcomes.
Fig. 4. Hyaluronic acid dermal filler in the lower infraorbital triangles (open arrows) on coronal MRI (T2FS)
Fig. 5. Delayed reaction to calcium hydroxyapetite, coronal MRI (T1FS, T2FS, T1FS with gadolinium).
Note the filler in the left infraorbital triangle (open arrows), with the delayed reaction extending to the nasolabial sulcus, causing the gross
asymetry
In the United States, “any physician who has participated in the care of a patient
can be named in a lawsuit if a case has been brought to court” 17]. Unlike in Europe, the prevailing party in frivolous cases cannot recover any legal
costs from the losing party 17]. In order to minimize the risk of incurring significant losses of time and money,
physicians who administer facial fillers and treat related complications should consider
using imaging to validate procedural outcomes. It is recommended that before providing
cosmetic care to a patient, all physical findings be photographically documented 18]. MRI could be implemented as an adjunct technique to evaluate asymmetry, overfilling,
and true complications, and determine whether the use of dermal fillers has a causal
relationship to any pertinent physical findings (Fig. 6). The utility of dedicated facial MRI should be stressed in cases of medico-legal
concerns, especially in light of the absence of ionizing radiation and negligible
gadolinium risk in healthy patients 19].
Fig. 6. Acute allergic reaction to hyaluronic acid in the left nasolabial sulcus and mouth
angle sulcus region (open arrows) on coronal MRI (T2FS, FS T1FS with gadolinium). This soft tissue reaction is often
reffered to “cellulitis-like.” Note the normal filler in the right lower infraorbital
triangle and nasolabial sulcus (arrowhead)
The main limitation of our study is sample size. There are other types of facial filler
substances on the market than are represented in the sample, and we have not yet had
the opportunity to characterize them using our novel MRI technique. Several non-face
dedicated techniques have been published in the literature 5], 7], and we did not perform a randomized trial to compare our technique to others; however,
the robustness of the Dixon sequences used, which include fat suppression and high
resolution field of view, alongside the added value of gadolinium injection, serves
as a precise and accurate all-encompassing facial imaging technique. The imaging and
clinical utility of this technique was highlighted by our high inter-rater statistics
and exquisite images.
Our reference table will be updated each time we encounter cases of complications
involving substances not yet seen. Given the growing awareness among referring physicians
of the value of dedicated facial MRI with gadolinium injection, we expect to see rising
numbers of MRIs performed on cases with and without complications after cosmetic intradermal
injectable filler procedures, to evaluate for symmetry and help referring clinicians
to provide their post-filler patients with the best possible health and esthetic outcomes.