Ultrasonographic and Shear Wave Elastographic Evaluation of the Effects of Collagen Thread Treatment on Skin Structure: A Prospective Study

Abstract

Background: Non-invasive skin rejuvenation techniques that stimulate collagen remodeling have gained increasing popularity in aesthetic dermatology.

Objective: Collagen thread treatment is a non-invasive cosmetic procedure based on topical application of collagen fibers derived from natural sources. This study aimed to evaluate the short- and mid-term effects of collagen thread treatment on epidermal, dermal, and subcutaneous tissues using ultrasonography (US) and shear wave elastography (SWE).

Materials and Methods: This prospective observational study included a total of 31 patients (30 females, 1 male) presenting with fine facial wrinkles. Collagen thread treatment was applied once weekly for three months. Baseline and third-month evaluations were performed in all patients. After completion of treatment, no additional procedures were applied, and a sixth-month follow-up was conducted to assess the persistence of treatment effects. Sixth-month data were evaluated in 16 patients.

Results: After three months of treatment, a significant increase in thickness was observed in all skin layers (p < 0.001). At the sixth month, epidermal and dermal thickness showed partial regression but remained significantly higher than baseline values (p < 0.01). Subcutaneous tissue thickness continued to increase. Elasticity values demonstrated a significant increase in the early period. No serious adverse events were observed.

Conclusion: Collagen thread treatment appears to be an effective non-invasive method capable of inducing structural changes in the skin without the need for invasive procedures. The effect appears to persist partially after treatment cessation, particularly in the subcutaneous tissue. Ultrasonography and SWE are reliable methods for objectively evaluating these changes.

Keywords: Collagen thread treatment; skin rejuvenation; ultrasonography; shear wave elastography; dermal thickness

Introduction

Collagen is the most abundant protein in the human body and constitutes the primary structural component of the skin and connective tissues. Collagen fibers in the dermis provide mechanical strength, elasticity, and structural integrity to the skin. With aging, collagen synthesis decreases and the structure of existing fibers deteriorates, leading to wrinkles, sagging, and loss of elasticity.

Ultraviolet radiation, smoking, hormonal changes, and environmental factors are major contributors to accelerated collagen degradation. Therefore, numerous invasive and non-invasive methods have been developed in aesthetic dermatology to stimulate collagen production.

Collagen thread treatment, which has become increasingly popular in recent years, is a non-invasive procedure involving the application of collagen fibers derived from natural materials or cocoon filaments onto the skin surface, where they interact with superficial skin layers. This application is thought to stimulate fibroblast activity, enhance collagen synthesis, and result in skin tightening.

The aim of this study was to objectively evaluate the structural effects of collagen thread treatment on skin layers using ultrasonography and shear wave elastography.

Methods

This prospective observational study included 31 patients (30 females and 1 male) who presented to the dermatology outpatient clinic with complaints of fine facial wrinkles. The mean age of the patients was 47 years (range: 28–59).

Collagen thread treatment was applied once weekly for three months (total of 12 sessions) by a trained aesthetic specialist. The procedure was performed on facial and cervical areas presenting with wrinkles, including the forehead, infraorbital region, nasolabial folds, and neck.

Prior to application, the skin was cleansed and disinfected. DS-V Line collagen threads derived from natural fibers and cocoon filaments were placed onto the skin surface using a customized tweezer technique without needle insertion. The number of threads used in each session was determined individually according to the patient’s clinical needs and the severity of wrinkles.

The threads were subsequently moistened with a proprietary serum to facilitate adherence and interaction with the skin surface. The serum contained hyaluronic acid, niacinamide, water, and castor oil. The threads were allowed to dissolve gradually while remaining in contact with the skin.

No invasive procedures were performed. Each treatment session lasted approximately 30 minutes. The procedure was painless and well tolerated, and no adverse events were observed during the treatment period. Patients were monitored throughout the study and were instructed not to undergo additional cosmetic procedures during the treatment and follow-up periods.

All patients were evaluated using ultrasonography at baseline and at the third month. The sixth-month follow-up was performed solely to assess the persistence of treatment effects, and data from 16 patients were obtained. Epidermal, dermal, and subcutaneous tissue thicknesses were measured using B-mode ultrasonography. All measurements were performed by the same operator under identical imaging conditions to minimize variability. Tissue elasticity properties were evaluated using SWE. All ultrasound examinations were performed by a single radiologist using the same ultrasound device. An ultrasound device (Aplio i800, Canon Medical Systems Corporation, Otawara, Japan) equipped with a multi-frequency linear array transducer (i18LX5) was used.

All imaging examinations were performed with the patient in the supine position from the right temporal region adjacent to the infraorbital area. When examining the described area, care was taken to apply a gel pad at least 1 cm thick. In B-mode US, the thickness of the epidermis, dermis, and subcutaneous layer was measured separately for each patient. The measurements were performed under similar standards in all patient examinations.

In SWE, the epidermis, dermis, and subcutaneous tissues of patients were again evaluated. The 2D-SWE map and propagation mode were examined in split-screen mode. The propagation mode provides reliable data when the lines appear parallel and smooth. In the spread mode, an increase in the distance between the lines is parallel to an increase in elasticity. Subsequently, a region of interest (ROI) with a diameter of 1 mm was used to take measurements at six different points in the axial plane. The ROI was placed twice in each region by the radiologist performing the sonography. To reduce measurement error, each recording was repeated at least twice, and the stiffness value was calculated as the average of the measurements. In all measurements, stiffness was recorded in meters per second (m/s).

Statistical analyses were performed using SPSS software. Baseline and third-month comparisons were evaluated using the Wilcoxon test, while three-time-point comparisons in patients with sixth-month data were analyzed using the Friedman test. A p value < 0.05 was considered statistically significant.

The study was approved by the local Institutional Ethics Committee and was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants.

Results

After three months of treatment, significant increases in epidermal, dermal, and subcutaneous tissue thickness were observed.

Mean epidermal thickness increased from 0.50 mm to 0.66 mm (p < 0.001). Dermal thickness increased from 1.02 mm to 1.31 mm (p < 0.001), and subcutaneous tissue thickness increased from 1.69 mm to 1.96 mm (p < 0.001).

At the sixth month, epidermal thickness was measured as 0.64 mm and dermal thickness as 1.20 mm, both remaining significantly higher than baseline values (p < 0.01). Subcutaneous tissue thickness reached 2.00 mm and continued to increase (Figure 1).

SWE evaluation demonstrated increased elasticity in the epidermis and dermis at the third month. At the sixth month, elasticity values decreased compared with the third month and approached baseline levels, with no significant differences observed in most parameters (Table 1).

Clinical evaluation revealed visible skin tightening and reduction of fine wrinkles (Figure 2).

Discussion

Collagen loss represents one of the fundamental mechanisms of skin aging resulting from both intrinsic and extrinsic processes, leading to weakening of dermal structure, loss of elasticity, and wrinkle formation (1–3). Age-related decline in fibroblast activity and degeneration of existing collagen fibers disrupt the structural integrity of the dermal matrix. Consequently, non-invasive approaches aimed at stimulating collagen production or reorganizing existing collagen have gained increasing popularity due to their low complication rates and minimal recovery time (4,5). The growing demand for non-surgical skin rejuvenation procedures in aesthetic dermatology has further emphasized the importance of treatments capable of inducing tissue-level remodeling.

In the present study, collagen thread treatment produced objectively measurable effects on skin structure. The significant increase in epidermal, dermal, and subcutaneous thickness observed after three months suggests that the procedure does not merely create a superficial cosmetic effect but may induce structural alterations in deeper tissue layers. In particular, the increase in dermal thickness may be explained by fibroblast activation, neocollagenesis, extracellular matrix deposition, and dermal remodeling. Previous studies evaluating energy-based devices and other non-invasive skin-tightening techniques have similarly reported increases in dermal thickness and collagen reorganization (4,5), indicating that collagen thread treatment may share common biological mechanisms with established non-invasive rejuvenation modalities.

Although partial regression in epidermal and dermal thickness was observed at six months, values remained above baseline levels, suggesting that the treatment effect is more likely attributable to true tissue remodeling rather than transient edema or inflammatory responses. In contrast, the continued increase in subcutaneous tissue thickness indicates that deeper tissue components may exhibit more sustained responses to treatment. Since collagen reorganization and extracellular matrix remodeling occur over extended periods, the persistent changes observed in the subcutaneous layer may reflect long-term biological effects of the procedure.

The marked early increase in tissue elasticity followed by gradual decline over time is consistent with the dynamic nature of collagen remodeling (6). Increased stiffness in the early phase may be associated with transient tissue reactions, compaction of collagen fibers, or inflammatory processes, whereas subsequent maturation and reorganization of newly synthesized collagen may stabilize the biomechanical properties of the tissue, resulting in elasticity values approaching baseline levels. Elastography studies have similarly demonstrated that tissue mechanical properties evolve over time and closely reflect underlying biological processes (6).

Objective imaging data regarding collagen thread treatment remain scarce in the literature. Most previous studies have relied primarily on clinical assessments, patient satisfaction scores, or subjective evaluation methods. In this context, the quantitative findings obtained through ultrasonography and shear wave elastography in the present study provide important objective evidence of treatment efficacy. High-frequency ultrasonography has been shown to reliably assess skin layer thickness and structural characteristics (7–10), while elastography enables quantitative evaluation of tissue stiffness and elasticity, making it increasingly valuable for assessing the biomechanical effects of aesthetic procedures.

The findings of this study suggest that collagen thread treatment induces not only superficial cosmetic improvement but also measurable structural changes at the tissue level. The persistent increase in subcutaneous thickness, in particular, indicates that the procedure may influence deeper tissue components and contribute to comprehensive skin remodeling. These results imply that collagen thread applications may play a broader role in skin rejuvenation beyond the correction of superficial wrinkles alone.

Conclusion

Collagen thread treatment appears to induce measurable structural changes in skin tissues, particularly within the subcutaneous layer, with partial persistence after treatment cessation. Ultrasonography and shear wave elastography provide objective and reliable methods for assessing these effects. These findings suggest that collagen thread treatment may represent a promising non-invasive option for skin rejuvenation, although further controlled studies are needed to confirm long-term efficacy and safety.

Funding

This study received no financial support from any pharmaceutical company, medical device manufacturer, or commercial organization.

Conflict of Interest

The authors declare no conflicts of interest related to this study.

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Figure 1. Mean Thickness of Skin Layers Following Collagen Thread Treatment

Table 1. Shear Wave Elastography (SWE) Outcomes

Parameter	3rd Month Observation	6th Month Observation	Clinical Meaning
Tissue Stiffness	Significant Increase	Regression to Baseline	Initial compaction vs. later maturation
Epidermal Elasticity	Increased (p < 0.05)	No significant difference	Dynamic collagen reorganization
Dermal Elasticity	Increased (p < 0.05)	No significant difference	Stabilization of biomechanical properties