Introduction: Facial Soft Tissue Defect Quantification for Fat Transfer by Using 3D Scanner and 3D Reconstructive Software : a Non-invasive Novel Approach
A patient photograph with temporary implanted quantified 3D printed templet .
Step 1: Introduction:
The face is the central organ for expression of emotion. Any deformity due to congenital, developmental or acquired cause decreases once self confidence and is considered as social stigma. The deformity can be at the level of bone or soft tissue or both. Diagnosis of deformity at bone level requires computerized tomography(CT) examination while Magnetic Resonance Imaging (MRI) is required for deformity at soft tissue level. Few causes of soft tissue facial deformity can be diagnosed just with patient’s history and clinical examination. In such cases the use of Computed Tomography or Magnetic Resonance Imaging may be unjustifiable. Thus an economical and non invasive method is required.
Here, we are presenting a case of Parry-Romberg Syndrome. A 35 year female having asymmetrical face with right side facial atrophy. On thorough detailed history and clinical examination, diagnosis was made as Parry-Romberg Syndrome Patient. Deformity was only at soft tissue level so, case was planned for abdominal fat transfer for facial defect but exact regions of defect cannot be marked by only clinical judgment. So we developed a non-invasive novel technique for the same. Which is very helpful for patient education and as a motivational tool as well as for communication among different surgeons. Owing to non-invasive and repeatable nature of this technique, it can be used multiple times during pre and post operative procedures. The technique is given as below:
Step 2: Step 1. Acquire a 3D Image With the Help of 3D Scanner: (figure 1,2,3 and 4)
Here we use Sense 3D scanner for full facial scan. For optimum quality facial scan, we should follow following strict instructions.
a. Position the patient- straight upright on stable stool
b. Patient is instructed not to move the head or any part of the face.
c. Connect the 3D scanner to the computer. The scanner should be 32cm away from center of face. The scanner is held in hand and slowly revolved around the face of the patient.
d. Process and edit the scanned face and export it as .stl file for further quantification of defect and 3d printing purposes.
Step 3: Step 2. Repairing of .stl File (figure 5 and 6)
Correction of .stl was done by using open source software Netfabb basic
a. Open .stl file .
b. Press on repair (‘+’) icon.
c. Click on automatic repair.
d. Select the default repair.
e. Then press on Execute.
f. Now click on apply repair.
g. Press on remove old part.
h. Then again right click on image and export file as STL.
Step 4: Step 3. Quantification of Defect by Using MIMICS ( Materialise NV, Belgium )
a. Import repaired .stl file in MIMICS software.(figure 7)
b. Divide the 3D object into two halves along the mid sagittal plane using cut with polyplane option. Split the object into two largest parts.(figure 8)
c. Mirror the left half face and superimpose on right half .(figure 9)
d. We find the multiple region where defect is anticipated.
e. Boolean subtraction operation is performed by subtracting original right half from the mirrored image. (figure 10)
f. The region of the defect are thus revealed. The subtracted object is than split into small parts. The significant large parts are retained and quantified. (figure 11 and 12) The volume of the defect can be known in the properties option of the object. This volume corresponds with the amount of fat required.
g. These defect object files are exported as *.stl file for 3D printing.(figure 13)
h. These 3D printed guides (figure 14) were used as guide to mark the areas requiring fat grafting.
i. Also made 3D printed whole face model for exact simulation of case for teaching and discussion purposes (figure 15A,B,C and D)
Step 5: Conclusion:
Hence, this non-invasive novel technique can be applied for fat transfer process in other soft tissue body part defect correction as well in soft tissue augmentation surgeries .