In response to the previous letter written by Dr. Swanson,1 we are very grateful for his interest in our paper and for spending the time to analyze and comment on it. We appreciate the opportunity to clarify our arguments and ideas that, we hope, can contribute to science and to plastic surgery practices. To support the members of this group, our clinical experience is based on long periods of research using fat grafting and stromal vascular fraction (SVF) of fat in treatment of the body and the face.2-8 We designed this study with the aim to evaluate the behavior of lipotransfer, comparing results of autologous lipotransfer to the face with or without enrichment of fat with its SVF, using objective and subjective methods of result measurement postlipotransfer.2 All the measurements data (box plots) from 10 patients are shown in Figure 4 of the paper. Regarding the main issue about the CT analysis, we have some important considerations. In order to determine fat graft viability, computed tomography (CT) scan was used to measure volumetrically the fat tissue as it evolved in the affected/treated areas (over time). CT scan can distinguish fat density from all other tissues, and was chosen over magnetic resonance imaging (MRI) because CT measurements are more exact than those of MRI and due to bony and orthodontics alterations/corrections in our patients.9 Hörl et al10 used MRI to study the long-term retention volume of fat and concluded that imaging, together with basic clinical observation, provides an objective evaluation of fat volume with an average error of only 5%; however, the volumetric measures are less exact than those made using CT scan. Har-Shai et al11 suggested the use of CT to quantify the volume of fat and concluded that this technique can distinguish the density of fat from other tissues. CT scan was used as an objective and quantitative method for measuring the retained rate of autologous fat graft. We agree about the patient radiation by CT exam comparing MRI; however, due to the reasons listed above, we have adopted the CT as an objective and quantitative method in our study. In our study, computed tomographic scans were obtained preoperatively and 12 months postoperatively for volumetric and soft-tissue thickness measurements of both hemifaces. Volumetric augmentation was noticed in each patient by comparing the difference between volumes of affected/treated areas, pre- and-postlipotransfer, and unaffected contralateral hemifaces, which was considered the absorption index. Results of fat-grafting procedures typically are assessed qualitatively by observation, handle examination, and photographs.12 Methods more objective—such as laser scanners, ultrasound, 3-dimensional (3D) photography, MRI, and computed tomographic imaging studies—are more available for assessing outcomes.13 Both CT and MRI acquire axial images of known thickness, usually 5 to 10 mm. Volumes are then calculated using geometric models based on the measured areas and the distances between adjacent slices.14 The 3D computed tomography with volume rendering enables measurement of distance, area, and volume.2,9,10 In our study, the radiologist delimited the affected/treated area through multiples slices of CT to the entire area (delimited from side to side of edges of the affected area) and submitted these images to specific software (Osirix MD software, Pixmeo, Bernex, Switzerland) provided by the manufacturer of the CT device (Siemens AG, Berlin, Germany).15 The volume of fat studied in the affected/treated areas by CT in these slices was between the skin (superficially) and the surface of the bone. This measurement could be incorrect because the wider the surface to be explored, the more likely the probability is of including fat from ungrafted areas, creating a bias to a lower viability of the grafted fat. For this reason, the radiologist defined the affected area of each patient to evaluate only the area of maximal atrophy in the hemiface. In the previous letter, this statement was cited: “For the 26-year-old woman with mild Parry-Romberg syndrome injected with 65 cm3 of enriched fat, the linear measurement perpendicular to the 45-mm long axis is labeled ‘20 mm’ on the preoperative image (Figure 1A of the paper). This length should be almost half the length of the 45- mm measurement. However, this length appears to be less than ¼ of the longer measurement.”1 Unfortunately, this mentioned perpendicular line should have reached the bone, as was showed in the CT image of Figures 2D and E of the paper. The 20-mm label line is correct. On the other hand, the previous letter claimed to inadequate linear CT measurements in Figures 1 and 2 of the paper, adopting some measures to analyze the area/volume. According to our comments above, the radiologist did many slices to measure the area and volume. Figures 1 and 2 of the paper show CT slices that were chosen to represent the area (volume) changes of the hemifaces in preoperative and postoperative time. Recently we have acquired the Vectra 3D imaging device (Canfield Scientific, Fairfield, NJ), which will be useful in our future studies. Disclosures The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article. Funding The authors received no financial support for the research, authorship, and publication of this article. REFERENCES 1. Swanson E. Does stromal vascular fraction supplementation improve facial lipotransfer? Aesthet Surg J . 2018; 38( 2): NP34– NP36. Google Scholar CrossRef Search ADS PubMed 2. Gontijo-de-Amorim NF, Charles-de-Sá L, Rigotti G. Mechanical supplementation with the stromal vascular fraction yields improved volume retention in facial lipotransfer: a 1-year comparative study. Aesthet Surg J . 2017; 37( 9): 975- 985. Google Scholar CrossRef Search ADS PubMed 3. Condé-Green A, de Amorim NF, Pitanguy I. Influence of decantation, washing and centrifugation on adipocyte and mesenchymal stem cell content of aspirated adipose tissue: a comparative study. J Plast Reconstr Aesthet Surg . 2010; 63( 8): 1375- 1381. Google Scholar CrossRef Search ADS PubMed 4. Condé-Green A, Baptista LS, de Amorin NFet al. Effects of centrifugation on cell composition and viability of aspirated adipose tissue processed for transplantation. Aesthet Surg J . 2010; 30( 2): 249- 255. Google Scholar CrossRef Search ADS PubMed 5. Charles-de-Sá L, Gontijo-de-Amorim NF, Maeda Takiya Cet al. Antiaging treatment of the facial skin by fat graft and adipose-derived stem cells. Plast Reconstr Surg . 2015; 135( 4): 999- 1009. Google Scholar CrossRef Search ADS PubMed 6. Charles-de-Sá L, Gontijo de Amorim NF, Dantas Det al. Influence of negative pressure on the viability of adipocytes and mesenchymal stem cell, considering the device method used to harvest fat tissue. Aesthet Surg J . 2015; 35( 3): 334- 344. Google Scholar CrossRef Search ADS PubMed 7. Rigotti G, Charles-de-Sá L, Gontijo-de-Amorim NFet al. Expanded stem cells, stromal-vascular fraction, and platelet-rich plasma enriched fat: comparing results of different facial rejuvenation approaches in a clinical trial. Aesthet Surg J . 2016; 36( 3): 261- 270. Google Scholar CrossRef Search ADS PubMed 8. Rigotti G, Marchi A, Galiè Met al. Clinical treatment of radiotherapy tissue damage by lipoaspirate transplant: a healing process mediated by adipose-derived adult stem cells. Plast Reconstr Surg . 2007; 119( 5): 1409- 1422; discussion 1423. Google Scholar CrossRef Search ADS PubMed 9. Fontdevila J, Serra-Renom JM, Raigosa Met al. Assessing the long-term viability of facial fat grafts: an objective measure using computed tomography. Aesthet Surg J . 2008; 28( 4): 380- 386. Google Scholar CrossRef Search ADS PubMed 10. Hörl HW, Feller AM, Biemer E. Technique for liposuction fat reimplantation and long-term volume evaluation by magnetic resonance imaging. Ann Plast Surg . 1991; 26( 3): 248- 258. Google Scholar CrossRef Search ADS PubMed 11. Har-Shai Y, Lindenbaum ES, Gamliel-Lazarovich A, Beach D, Hirshowitz B. An integrated approach for increasing the survival of autologous fat grafts in the treatment of contour defects. Plast Reconstr Surg . 1999; 104( 4): 945- 954. Google Scholar CrossRef Search ADS PubMed 12. Tanikawa DY, Aguena M, Bueno DF, Passos-Bueno MR, Alonso N. Fat grafts supplemented with adipose-derived stromal cells in the rehabilitation of patients with craniofacial microsomia. Plast Reconstr Surg . 2013; 132( 1): 141- 152. Google Scholar CrossRef Search ADS PubMed 13. Fontdevila J, Serra-Renom JM, Raigosa Met al. Assessing the long-term viability of facial fat grafts: an objective measure using computed tomography. Aesthet Surg J . 2008; 28( 4): 380- 386. Google Scholar CrossRef Search ADS PubMed 14. Shen W, Wang Z, Tang Het al. Volume estimates by imaging methods: model comparisons with visible woman as the reference. Obes Res . 2003; 11( 2): 217- 225. Google Scholar CrossRef Search ADS PubMed 15. Kim G, Jung HJ, Lee HJ, Lee JS, Koo S, Chang SH. Accuracy and reliability of length measurements on three-dimensional computed tomography using open-source OsiriX software. J Digit Imaging . 2012; 25( 4): 486- 491. Google Scholar CrossRef Search ADS PubMed © 2017 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: email@example.com
Aesthetic Surgery Journal – Oxford University Press
Published: Feb 1, 2018
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