The Effects of Non-Invasive External Ultrasound On Tissue Temperature and Adipocyte Morphology

The Effects of Non-invasive External Ultrasound on Tissue Temperature and Adipocyte Morphology

 

  Goals/Purpose:   This past decade has seen a significant decline in liposuction with a 44% decrease in the number of procedures reported [1].  During this same period there has been a significant proliferation of non-invasive body contouring devices in the marketplace.  The VASER Shape is a non-invasive ultrasound (US) system which received FDA clearance in 2010 for relief of pain, muscle spasms and joint contractures [2].  The device has been used “off- label” for non-invasive body contouring on the premise that US diathermy may have a reducing effect on adipose tissues.  This study documents both the time/temperature relationships and cellular changes following VASER Shape treatments.

Methods/Technique: This study (DB 334) was conducted in compliance with all IACUC protocols regarding treatment of laboratory animals. Treatment and control areas were marked on the lower abdomen of 3 anesthetized 70 kg Yorkshire pigs.  Thermocouples were placed into the treatment area at depths of 2mm, 14mm and 30mm under Touchview ultrasound guidance (Fig. 1).  Tissue temperatures were recorded throughout the treatment phase [3, 4].  Treatments were applied at manufacturer's recommended settings for 12 minute intervals.  A thermal camera recorded skin surface temperature (Fig.2).  Lymph samples were taken pre-treatment from control side and post treatment from treated side.  Biopsies were taken of the skin, adipose tissues and lymph nodes on both the control (pre-treatment) and the VASER-Shape treated side (post-treatment).  The skin specimens were evaluated via TriChrome and NADH stains.  The lymph nodes samples were evaluated by electron microscopy and also treated with Oil Red O stain.  The adipose tissue was evaluated by electron microscopy.

                                                                              

Figure 1. Thermocouples in treatment areas.

 Figure 2. Skin temperature monitoring via thermal camera.

   

 Results/Complications:   The skin biopsies did not reveal evidence of thermal damage.  Lymph analysis revealed that average triglycerides values were 1598 mg/dl treated side versus 232 mg/dl for control.  Analysis of lymph node biopsies revealed free vacuoles of fat within the lymph node tissue on treated side compared to normal lymph node histology on control side (Fig. 3).  Post treatment side lymph nodes stained with Oil Red O as opposed to the control (Fig. 4).  Temperature measurements for typical study subject are depicted in (Fig. 5).  Electron microscopy of the treated adipose tissue revealed alterations in the cellular architecture without necrosis. (Fig. 6).

 

Control                                                                                                     

Post treatment

Figure 3.  Control LN displays normal histology, post treatment LN contains numerous free lipid vacuoles.

Figure 5.  Time/temperature relationships.

Figure 6. Electron microscopy of treated adipose tissue displays 3 adipocytes with intact cell walls and free lipids within the extracellular space.

 

 Conclusion:   The tissue temperatures produced were not associated with thermal tissue damage at energy levels recommended for clinical use. Based on the 7 fold increase of free lipids in the lymph system following the treatments, the increase in free lipids within the lymph nodes on the treated side and the cellular changes (free lipids in the extracellular space without fat cell necrosis), we conclude that treatment with this device may have a reducing effect on adipose tissue at clinically relevant energy settings, possibly by altering the permeability of the adipocytes.

References                                                                                                                                                                                             

1.  American Society for Aesthetic Plastic Surgery Statistics 2010.

2.  ter Haar G. Therapeutic ultrasound. Eur J Ultrasound 9: 3- 9, 1999.                                                                   

 3.  Hendrik Demmink J.,  Helders P., et al. The variation of heating depth with therapeutic ultrasound frequency in physiotherapy. Ultrasound in Med.&Biol 29: 113-118, 2003.                                                                                           

4.  Lorincz A.  Application of the ultrasound hyperthermia model for a multi-layered

     tissue system. J  Physics conference series, 1: 224-229, 2004.

Disclosures/Financial Support

This study was conducted according to IACUC protocol and funded by Sound Surgical Technologies (Louisville, CO).   The study was presented in part at the Research and Technology section of the 2011 ASPS annual meeting.