The non-invasive treatment of Fat Reduction and the results measurement
Currently available noninvasive fat reduction and body shaping procedures include cryolipolysis (coolsculpting and cool shaping) (coolsculpting and cool shaping), photobiomodulation (sculpsure ), radiofrequency (Vellashape), high-intensity focused Ultrasound (Vellashape and Ultrashape ) (Ulthera), and chemical adipocytolysis (meso-injection). Lots of studies have shown the safety and effectiveness of these procedures, but there is lack of the quantitative measurement techniques selected for demonstrating improvement. The different methods used can complicate the comparison of outcomes across trials.
The purpose of this post is to report the measurement of in vivo fat change after noninvasive treatment and to discuss the pros and cons for each one of them.
Reviewing all the articles that studied the fat reduction, body shaping and body slimming including The various methods of noninvasive fat reduction— cryolipolysis (coolsculpting and cool shaping) (coolsculpting and coolshaping, photobiomodulation (Sculpsure), radiofrequency (Velashape and Ultrashape), chemical lipolysis, and high-intensity focused Ultrasound ( vellashape and ultrashape )(Ulthera)—were statistically equally.
The results of the fat reduction were reported using one and five assessment methods for fat reduction. Most studies utilized four or more techniques. Circumference measurements were most commonly reported. Other objective techniques such as caliper measurements, Ultrasound ( vellashape and ultrashape ), magnetic resonance imaging (MRI), and three-dimensional (3D) photography were also used. Standardized photographs and patient satisfaction surveys were the most commonly reported subjective methods.
In fact, fat reduction and body shaping were investigated by a large number of research articles. Typical study goals include detection of clinically meaningful, cosmetically beneficial, and statistically significant improvements. Since individual treatments of noninvasive fat reduction often lead to subtle changes that are not immediately discernible, there are difficulties inherent in such measurement, and hence variability in the quantification techniques across studies. Unlike more invasive techniques like abdominoplasty or liposuction, which may result in clearly evident changes in body contour after a single procedure, noninvasive contouring may generate significant improvement, but over the course of several treatments which provide incremental benefits.
Limitations of commonly used methods and potential solutions are summarized in the table below. Circumference measurements were most often reported as a tape measure is an inexpensive and readily accessible option requiring minimal technical skill. However, while girth assessment may intuitively appear valid, values can be biased by patient-specific factors (e.g., patient position, fluid retention, height, misalignment of anatomic landmarks, the bulkiness of clothing, recency of bowel movements, weight changes, respiration) and influenced by the measurer through the degree of external pressure applied. Controlling for weight and focusing on isolated body parts, like the upper arms, as well as taking the measurement at the same time of day may help reduce measurement error. Self-adhering tape that does not require external manual compression or an apparatus that standardizes tension, may also improve reproducibility.
Table 2. Limitations and potential solutions for commonly used measurement techniques
|Circumference||1) Affected by positioning, posture, height, dress, bloating, weight changes, and breathing||1) Repetitive measures 2) Controlling for weight 3)Self-adhering tape or apparatus with constant height and tension|
|Ultrasound ( vellashape and ultrashape )||1) Landmarks subjectively assigned 2) User dependent 3) Compression of fat layer by transducer||1) Template to make marks on the patient to guide Ultrasound ( vellashape and ultrashape )|
|MRI||1) Availability and high cost 2) Dependent on respiration||1) Limit use for measurements on extremities|
|Photographs||1) Affected by positioning and lighting 2) Potentially biased if ratings performed by study investigator||1) Standardize conditions. Use blinded evaluator|
Ultrasound ( vellashape and ultrashape ) is an appealing measurement method as it is technologically more sophisticated than a tape measure, widely accessible, and able to visualize the fat layer. On the other hand, designation of landmarks, which are critical for reproducibility, is inherently subjective and may be difficult to precisely replicate across sessions. Ultrasound ( vellashape and ultrashape ) is also highly user dependent, and pressure from the transducer can compress the fat layer making findings less reproducible. Transparencies with anatomical landmarks indicated have been used by some to facilitate consistent ascertainment. Importantly, it is unclear how much of a change in fat layer thickness is needed to induce the minimum detectable change on Ultrasound ( vellashape and ultrashape ). Thresholds of detection may differ for individual patients and may improve with technological advances. Most relevant investigations did not specify whether the technical acquisition of the Ultrasound ( vellashape and ultrashape ) studies was by an Ultrasound ( vellashape and ultrashape ) technician or an investigator]. In one study a blinded radiologist was said to be the evaluator.
MRI is more reproducible and less user-dependent than Ultrasound ( vellashape and ultrashape ), but the high cost of scans can be prohibitive for research. Additionally, fat reduction studies are frequently performed in private practice settings which may not have access to MRI. Reliability of MRI for fat measurements appears to be greater on the extremities than the trunk, which moves with respiration. When MRI is used, complex computations are required to derive volumetric measurements from 2- and 3-dimensional image slices centered on a relevant tissue plane and obtained under conditions of consistent subject positioning.
Standardized photographs were taken as part of almost every contouring study reviewed. Blinded observer ratings were less common. Studies utilizing blinded review often entailed blinded evaluators being able to reliably choose between the baseline and treated side. Even when observers were blinded, they were usually subject to the pitfalls of relying on static photographs, which can vary due to position and lighting. Blinded ratings also rely on the sensitivity of the rater, with the so-called expert or trained observers likely more attuned to minor changes than casual observers. However, this does not make the findings of trained observers any less valid than those of untrained observers. Similarly, while blinded observer ratings are subjective and may be flawed in particular circumstances, they have the distinction of being largely unbiased. At a philosophical level, while patients have various reasons for undergoing noninvasive fat reduction procedures, the usual goal is to achieve the aesthetic improvement that can be detected by the human eye, and this type of change is best captured by a trained, blinded observer.
Observer rating scales based on photographs tend to be ordinal, with higher values associated with improved outcomes. Some scales value outcomes in the absolute sense, from bad outcomes to better and best; other scales compare outcomes relative to a starting point (e.g., much improved, slightly improved, no change, slightly worsened, much worsened). The number of rungs in scales also varies. Not all observer and patient scales are formally validated, but validated scales are considered reliable and are accepted as primary outcome measures by the US Food and Drug Administration (FDA) and other regulators.
Many studies included a patient reported the outcome, most commonly a patient satisfaction survey. The design of these surveys was variable. Often subjects were queried on overall satisfaction, which might be reported as a percentage, or on an ordinal, Likert-type scale, as well as whether they would have the procedure again or recommend it to a friend. Patients were also asked to report the degree of improvement, either overall improvement (e.g., on a Global Aesthetic Improvement Scale), or improvement on specific parameters (e.g., compactness, volumetric reduction of fat, and comfort) or at particular anatomic sites (e.g., submental area)
To address the need for more objective reproducible measurements, efforts are underway to develop and validate new instruments that characterize volumetric changes. Garibyan et al. utilized a 3D camera to obtain quantitative volume measurements after treatment with cryolipolysis (coolsculpting and cool shaping). Preliminary work has been performed to validate 3D imaging for measurement of body circumference. A so-called “lipometer” comprised of a light emitting diode and photodetector placed at strategically selected points can help assess fat thickness and yield volumetric totals. Mathematical models for quantifying fat reduction are also being developed. A faux-fat simulation method has been used to populate a geometric prediction model comparing torso circumference and abdominal fat layer reduction. Further work is required to ensure that computed quantitative measures correspond with real physical changes as well as blinded ratings.
Although the FDA requests reporting of performance data in the approval process, there are no rigid specifications as to the particular measures. Individual companies seeking approvals submit plans for clinical studies with proposed metrics, and FDA may respond with suggestions to render these more suitable for regulatory assessment. For body contouring devices, ordinal outcome scales assessed by blinded raters have been used, with FDA requiring that a certain proportion of raters note a post-treatment improvement of a certain degree (e.g., 1 or 2 points on the rating scale). Scales may be developed for a single study, and FDA may want a simple validation before their use. Fat layer measures, including circumference measured in centimeters, fat assessed by Ultrasound ( vellashape and ultrashape ) compared to baseline and sham treatment, and MRI, have also been accepted as key metrics. Patient-reported outcomes such as patient surveys are additionally considered by FDA. In general, the data required for device approval is more substantial than that required for clearance of a device similar to one that has already been approved (i.e., a predicate device) through the 510K process. FDA’s Center for Devices and Radiological Health has a forward-seeing administration that is open to improved measurement methodology.
Skeptics of noninvasive fat reduction may attribute the subtle improvements to weight loss. However, all reviewed studies except for one monitored baseline and post-treatment weight, usually requiring subjects to maintain weight or BMI within a narrow band during the study course. However, despite study admonitions to maintain previous lifestyle and diet, subjects may be motivated to change behavior to a healthier lifestyle.
There are no systematic data that suggest that any method of detecting noninvasive fat change is relatively more generous, that is, likely to show a greater change with an equivalent fat-reducing stimulus. In general, the less precise and reproducible methods may produce more variable outcomes, including possibly dramatic benefits, and due to potential publication bias, may be more highly represented in the literature.
Limitations of this study include that few head-to-head studies have compared the accuracy and precision of different fat measurement methods. Another limitation was that some articles might have been missed using Boolean system search strategy “AND ‘fat reduction’,” because some articles might not have referred to “fat reduction” as a singular term. Future advances in measurement are also beyond our ability to evaluate.
This study suggests that there is no single measure of subcutaneous fat change that supersedes all others in reliability and utility. For the foreseeable future, when assessing specific studies, investigators and patients will need to consider several such measures, keeping in mind measure-specific strengths and limitations. Similarly, investigators embarking on new effectiveness studies of noninvasive fat reduction will need to deploy multiple measures, carefully selected to collectively provide accurate and complete information about outcomes.
In reviewing studies of body contouring to date, we found no single objective technique that is sufficient for quantifying noninvasive fat reduction. Circumference measurements are easily obtainable but fraught with variability. Ultrasound ( vellashape and ultrashape ) is a readily accessible method to measure fat thickness, but accuracy can be highly dependent on operator expertise. MRI is likely reliable at quantifying fat on the extremities, but feasibility in studies is limited by high costs and availability and the complexity of the protocols that are necessary to make this modality reproducible. Subjective measures like blinded observer ratings of standardized photographs, or patient-reported outcomes, also have value. Subjective measures may most closely mimic the ultimate goals of the patient, who wants a perceptible improvement in body contour.
We propose a standard routine method for measuring fat reduction that entails the concurrent use of multiple measurement modalities such as circumference measurements, Ultrasound ( vellashape and ultrashape ) measurements, MRI if possible, blinded ratings of standardized photographs, and patient-reported outcomes. Weight measurements taken at the same time of day should always be included to determine if the fat reduction or lack thereof could be attributed to changes in weight. Standardized photographs should also always be included to show the change or lack thereof of the contour of the treated area. Widespread use of such a common measurement standard may facilitate comparative effectiveness studies and guide further refinement of current technologies and devices.
Important note: most of the post info and paragraph were taken and cited from an article published by Poon et al. entitled ” Quantification of noninvasive fat reduction: A systematic review” published in Lasers in Surgery and Medicine
Dr. Kamal Alhallak
Ph.D., MSc, CDE, CRE, APA, MBA candidate