It is important to be familiar with radiological appearance because potential microcalcifications and fat nodules were the major criticism raised against fat transfer. Moreover, as we have seen, these virulent criticisms led to the abandon of fat transfers in the breast at the end of the 1980s and to the halting of research studies and of publications on the subject. Transfers were suspected of interfering with the diagnosis of a potential breast cancer. However, over the last 20 years radiological techniques have considerably improved, enabling much more precise diagnosis of the breast parenchyma and of any abnormalities. In addition, the development of small-gauge and large-gauge needle core biopsies since 1990 provides a histologic result that is as reliable as a surgical biopsy, using a percutaneous technique under local anesthesia. In most cases, these biopsies give a definitive diagnosis without the drawbacks of surgery and can easily be proposed if any breast abnormality is considered suspicious. With our team of radiologists, we have taken particular care to define precisely all images that may be encountered after lipomodeling for the sequelae of conservative treatment of breast cancer.26
Images Resulting from Lipomodeling
The formation of microcalcifications can be considered as a normal consequence of lipomodeling because it concerned 20% of our patients at 1 year, but it is also a normal and frequent effect of any breast surgery.27,28 Moreover, in our series we observed that conservative treatment had also resulted in 20% of microcalcifications before lipomodeling (reflected in a total of 40% of microcalcifications at the end of treatment at 1 year).
The frequency of microcalcifications after lipomodeling is thus similar to that developing after conservative treatment. As in many types of breast surgery other than lipomodeling, these calcifications have no diagnostic or therapeutic consequences. Radiologically, microcalcifications following breast surgery or adipocyte transfer are benign in appearance. In the literature, there are few or no systematic studies of the formation of calcifications after lipomodeling, but it has been shown that calcifications may be found in 50% of cases 2 years after breast reduction.27 Also, in this indication, the development of these calcifications has never been accused of interfering with the diagnosis of cancer. Calcifications on fatty necrosis are in most cases easily recognizable, classified as benign and dystrophic, very different from the suspect microcalcifications of recurrence. Our team has carried out 3 studies evaluating the radiological impact of lipomodeling. The first study concerned lipomodeling of breasts reconstructed with latissimus dorsi flaps,6 the second concerned breasts after conservative treatment,26 and the third, breast deformities treated by lipomodeling. All 3 studies concluded there was no harmful impact on the surveillance and radiological diagnosis of a breast abnormality. In the same spirit, we organized on May 12, 2007, in Lyons, France, a day symposium on breast imaging and plastic surgery. The radiological experts who were present unanimously maintained that fat transfer, properly performed, had no deleterious effect on breast imaging. Some even emphasized that "fat is the ally of the radiologist" because of its radiolucent nature that improves contrast and makes abnormalities easier to recognize.
Focal fat necrosis may develop. but if the technique of transfer by reinjecting fat without forming a fatty pool is respected, and if the tissues are not oversaturated, it can be avoided.4 We consider that clinical fat necrosis generally corresponds to a lack of experience (the principles of the 3-dimensional network and avoidance of oversaturation were not respected).
The radiological presentation is much more frequent, and it is variable: Generally, oily cysts are seen (57% in our series), and their diagnosis is evident whether by mammography or ultrasound: round, regular microcalcifications with a radiolucent center classified ACR 2 (19% in our series), which are not suspicious and are readily distinguishable from those that accompany a recurrence. More rarely, we have observed the formation of a mixed, complex cystic image with a fluid and semisolid component (19%), but here again the diagnosis of fat necrosis was made without difficulty. Radiologists with a particular interest in mammography are familiar with these images because it must not be forgotten that fat necrosis, like microcalcifications, appears after all types of breast surgery: biopsy, conservative treatment, breast reduction,27 breast reconstruction,28 or liposuction. It was noteworthy that in our series 15% of patients already presented images of fat necrosis on ultrasound and 20% on mammography, after conservative treatment and before lipomodeling. Overall, after lipomodeling, 76% of patients presented images of fat necrosis visible on ultrasound, of which most (57%) were simple oily cysts, whose diagnosis was never in doubt. In our experience, the risk lies in the fact that unfamiliarity with the subject may lead to a suspicious image being wrongly attributed to a consequence of lipomodeling and also that a recurrence may pass unrecognized. However, it is easy to make the diagnosis of benignity or malignancy, whether by mammography,28 ultrasound,29 or MRI.30
If there is the slightest doubt, certainty must be established by histologic diagnosis obtained by small-gauge or large-gauge needle core biopsy. It must be stressed here that an expert opinion should not be sought: If there is any doubt, certainty must be obtained by histology.
The percentage of images induced by lipomodeling may appear high. It is, however, comparable with that obtained after conservative treatment by oncoplastic surgery (primary mammoplasty and radiotherapy) for primary treatment of breast cancers, a technique that is now advocated by numerous leading teams in breast cancer surgery. Imaging investigations must therefore be interpreted with discernment, putting them in perspective and comparing them with the results of oncoplastic surgery, which has the same objectives: to offer at term the best possible results of conservative treatment. So it appears that lipomodeling carried out for correction of the sequelae of conservative treatment does not generate an image that leads to confusion with breast cancer. Nor does it hinder the diagnosis of a possible local recurrence or of a new cancer.
Protocol for Radiological Follow-Up
Surveillance of the treated breast is primarily clinical. At the present time, there is no reference radiological protocol for breasts reconstructed by lipomodeling. According to the results obtained, mammography appears to be indispensable because it is the most efficient modality for the diagnosis of microcalcifications. Ultrasound is also necessary because it is the best technique for detecting images of fat necrosis. In contrast, MRI seems to us to be of little value unless recurrence is suspected.26
Images of fat necrosis, notably microcalcifications, continue to appear after 1 year. It seems opportune to continue mammographic and ultrasound surveillance, generally yearly, according to the recommendations of the radiologist in charge of the patient's follow-up.26