Response to "comments on 'evaluation of a microfocused ultrasound system for improving skin laxity and tightening in the lower face'".

We thank Dr Friedmann for his thoughtful comments. Striving for objective measurements to guide clinical efficacy is clearly important, particularly in this field. Our study has tried to address this issue by utilizing a number of measurements, both qualitative and quantitative. We recognize that validated subjective and objective measurements remain the gold standard in clinical research. Three-dimensional (3D) imaging was used for all our subjects (Vectra M3, Canfield Imaging, Fairfield, NJ). We captured the 3D images using Mirror software’s alignment method, which utilizes two pairs of vertical lines and one pair of horizontal lines to align the position of the subject’s head. This technique eliminates variation in the positioning of the subject’s height, distance from the camera, and rotation of the head. Then we saved the 3D images to 2D to perform the quantitative analysis as described in the manuscript. We recognize and appreciate that a change in head position, particularly anteriorly, can have an impact on the appearance of the neck and impair objective assessment. We also recognize that standardizing the neck position is an equally important endeavor. We are not familiar with any other method to establish consistent head position and feel confident that we undertook this in an objective manner. The points used for the quantitative measurement were fixed for each subject. In this way we have attempted to minimize the amount of variables and have created an objective assessment of the change in the contour of the neck. Whilst we take the point that this is not a validated method, the quantitative methodology was approved by the US Food and Drug Administration after extensive consultation. We understand that the removal of fat via weight loss or surgery may have an impact on contour. We agree that weight measurements would help assess this confounding variable. We specifically looked at the effect of body mass index (BMI) and its influence on the qualitative assessment. Indeed, we demonstrated that if you look specifically at those with a high BMI the efficacy goes down to 50%. This is important in patient selection when considering using this device. A review of our article will confirm that the results of the subjective or qualitative methodologies were all included in the manuscript in the Results section. Both patient satisfaction scores (65.6% improved) and scores for the masked clinical observers (58.1% improved) were reported. Interestingly, despite not being officially validated, there was good correlation between the quantitative and qualitative results. Of those patients that showed a qualitative improvement, 82.1% felt they had improved on the patient satisfaction survey and 75% from masked clinician assessments. We want to thank Dr Friedmann for his insight and comments regarding our study, the largest cohort of patients treated with this device. Long hours were undertaken to create a study that objectively assessed this device and we feel our data does measure it qualitatively and quantitatively in an unbiased manner. We look forward to publications by plastic surgeons and other colleagues, such as Dr Friedmann, in the future to help us answer many of our challenges in aesthetic surgery.