Measuring Temperature Induced Phase Change Kinetics in Subcutaneous Adipose Tissues Using Near Infrared Spectroscopy, MR Imaging and Spectroscopy and OCT

Abstract

Monitoring phase transition in adipose tissue and formation of lipid crystals is important in Cryo-procedures such as Selective Cryolipolysis (SC). We exploited a Near-Infrared Spectroscopy (NIRS) method to monitor the onset of fat phase transition (freezing/melting) in human abdominal adipose tissue. The changes in optical scattering were compared to Differential Scanning Calorimetry (DSC) measurements as the gold standard method for measuring phase transition. For some samples, concurrent in vitro measurements of optical scattering using NIRS and the MR signal parameters (T2*) as well as spectral parameters using MR Spectroscopy were performed in a 3 T MR scanner during a cooling/heating cycle. To further investigate phase-transition in adipose tissue in microscopic level, an identical cooling/heating procedure was replicated on a small piece of fat harvested from the same tissue while being imaged under Optical Coherence Tomography (OCT). For all methods, their relationship with temperature shows inflexions in a narrow range, characteristic of lipid phase transition. In particular, the good agreement between DSC and Optical measurements suggests that such NIRS methods can be used to improve dosimetry and to minimize variations of clinical outcome for cryo-procedures.

Abdominal Fat Reduction through Cryolipolysis

“…We could not find any clear biological plausible mechanism why the cross sectional areas of visceral adipose tissue decreased. However, we suggest that cooling method might induce apoptosis in visceral fat beyond peritoneum depending upon the depth of thermal probe according to recent experimental study [20]. Visceral fat associated hormone such as vaspin, adipokine with Cryolipolysis is still relatively new technology that requires further research.…”

Cryolipolysis: The future of cryolipolysis

“…37,39 MRI offers a more precise and objective quantification of fat volume loss, 36 and has been used to quantify submental fat volume reduction with other fat loss procedures. 40 One study evaluated the phase change kinetics of adipose tissue from human pre-abdominoplasty patients using MRI, 38 implying that MRI may ultimately be developed into another way of monitoring the progress and efficacy of cryolipolysis applicators and devices. Finally, new techniques such as 3D body scanning have been evaluated to successfully quantify the volume of fat loss after cryolipolysis treatments.…”

“…Advanced imaging techniques, such as ultrasound, magnetic resonance imaging (MRI), and threedimensional body scanning, are also emerging as valuable tools for adipose assessment with potential for use in personalized cryolipolysis. 5,24,[36][37][38] Ultrasound, which can be done in-office, is the best modality to assess the thickness of subcutaneous adipose tissue, and has long been used as a tool for evaluating fat loss objectively in cryolipolysis studies. 37,39 MRI offers a more precise and objective quantification of fat volume loss, 36 and has been used to quantify submental fat volume reduction with other fat loss procedures.…”

“…These local measurements can be effective in tracking and monitoring progress. Advanced imaging techniques, such as ultrasound, magnetic resonance imaging (MRI), and three‐dimensional body scanning, are also emerging as valuable tools for adipose assessment with potential for use in personalized cryolipolysis 5,24,36–38 . Ultrasound, which can be done in‐office, is the best modality to assess the thickness of subcutaneous adipose tissue, and has long been used as a tool for evaluating fat loss objectively in cryolipolysis studies 37,39 .…”