@article{10.1117/1.JBO.30.3.035002,
author = {Hinnerk Schulz-Hildebrandt and Michael Wang-Evers and Naja Meyer-Schell and Daniel Karasik and Malte J. Casper and Tim Eixmann and Felix Hilge and Reginald Birngruber and Dieter Manstein and Gereon H{\"u}ttmann},
title = {{Optical coherence tomography needle probe for real-time visualization of temperature-induced phase changes within subcutaneous fatty tissue}},
volume = {30},
journal = {Journal of Biomedical Optics},
number = {3},
publisher = {SPIE},
pages = {035002},
abstract = {Significance: Selective cryolipolysis is a widely used aesthetic procedure that cools subcutaneous adipose tissue to temperatures as low as −11°C to induce fat cell destruction. However, real-time monitoring techniques are lacking, limiting the ability to optimize safety and efficacy. Traditional imaging methods either fail to provide adequate penetration depth or lack the resolution necessary for visualizing subcutaneous fatty tissue dynamics.Aim: This paper aims to demonstrate that an optical coherence tomography (OCT) needle probe can be used for real-time observation of temperature-induced changes in subcutaneous fatty tissue, potentially enhancing the assessment and optimization of cryolipolysis procedures.Approach: We developed a side-viewing OCT-based needle probe designed for subcutaneous imaging. The probe consists of a fiber-optic system encased in a transparent, biocompatible polymer catheter with an outer diameter of 900 μm. A 49-degree angled fiber enables imaging, while a piezoelectric scanning system moves the fiber transversely within the catheter. The probe achieves a lateral resolution of <15 μm, a working distance of 600 μm, and a lateral field of view dictated by the scanning system length. OCT imaging was performed on porcine skin with a subcutaneous fat layer >3 cm thick during controlled heating and cooling.Results: OCT imaging revealed increased optical scattering in subcutaneous fatty tissue during cooling, corresponding to the phase transition from liquid to solid. This effect was reversible upon warming, indicating that OCT can dynamically monitor adipocyte crystallization in real time. The observed transition temperatures varied, likely due to differences in lipid composition.Conclusions: OCT-based needle imaging enables direct, high-resolution visualization of adipocyte crystallization, offering a potential tool for optimizing selective cryolipolysis treatments. This technology could improve safety and efficacy by providing real-time feedback on tissue response, facilitating a better understanding of the cooling-induced fat reduction process.},
keywords = {optical coherence tomography, endoscope, fiber probe, cryolipolysis, Optical coherence tomography, Adipose tissue, Tissues, Visualization, Crystallization, Skin, Tissue optics, Scattering, Monochromatic aberrations, Refractive index},
year = {2025},
doi = {10.1117/1.JBO.30.3.035002},
URL = {https://doi.org/10.1117/1.JBO.30.3.035002}
}

@inproceedings{10.1117/12.2577822,

title = {Novel method to assess the impact of aging and sun exposure on skin morphology by optical coherence tomography},

author = {Felix Hilge and Michael Evers and Malte Casper and Joshua Zev Glahn and Weeranut Phothong M.D. and Garuna Kositratna M.D. and Hinnerk Schulz-Hildebrandt and Gereon H\"{u}ttmann and Dieter Manstein M.D.},

editor = {Bernard Choi and Haishan Zeng},

url = {https://doi.org/10.1117/12.2577822},

doi = {10.1117/12.2577822},

year  = {2021},

date = {2021-01-01},

booktitle = {Photonics in Dermatology and Plastic Surgery 2021},

volume = {11618},

publisher = {SPIE},

organization = {International Society for Optics and Photonics},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@article{RN5217,
   author = {Spahr, Hendrik;Pfäffle, Clara;Burhan, Sazan;Kutzner, Lisa;Hilge, Felix;Hüttmann, Gereon and Hillmann, Dierck},
   title = {Phase-sensitive interferometry of decorrelated speckle patterns},
   journal = {Scientific Reports},
   volume = {9},
   number = {1},
   pages = {11748},
   ISSN = {2045-2322},
   DOI = {10.1038/s41598-019-47979-8},
   url = {https://doi.org/10.1038/s41598-019-47979-8},
   year = {2019},
   type = {Journal Article}
}

@article{Hillmann2019,
   author = {Hillmann, D.;Pfaffle, C.;Spahr, H.;Burhan, S.;Kutzner, L.;Hilge, F. and Hüttmann, G.},
   title = {Computational adaptive optics for optical coherence tomography using multiple randomized subaperture correlations},
   journal = {Opt Lett 44 (15)},
 
   pages = {3905-3908},
   ISSN = {1539-4794 (Electronic)
0146-9592 (Linking)},
   DOI = {10.1364/OL.44.003905},
   url = {https://www.ncbi.nlm.nih.gov/pubmed/31368998},
   year = {2019},
   type = {Journal Article}
}

@article{Pfäffle2019,
   author = {Pfäffle, C;Spahr, H;Kutzner, L;Burhan, S;Hilge, F;Miura, Y;Hüttmann, G and Hillmann, D},
   title = {Simultaneous functional imaging of neuronal and photoreceptor layers in living human retina},
   journal = {Optics Letters 44(23)},
 
   pages = {5671-5674},
   DOI = {10.1364/OL.44.005671},
   
   year = {2019},
   type = {Journal Article}
}