Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, 02129, USA.
Cutaneous Biology Research Center, Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, 02129, USA.
Sci Rep. 2017 Dec 19;7(1):17786. doi: 10.1038/s41598-017-18145-9.
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 (T*) 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.
监测脂肪组织的相变和脂晶的形成对于冷冻程序（如选择性冷冻解脂术）非常重要。我们利用近红外光谱（NIRS）方法来监测人类腹部脂肪组织中脂肪相转变（冷冻/融化）的开始。将光学散射的变化与差示扫描量热法（DSC）测量结果进行比较，后者是测量相变的金标准方法。对于一些样本，在 3T 磁共振扫描仪中，在冷却/加热循环期间，使用 NIRS 和磁共振信号参数（T*）进行光学散射的同时进行体外测量，以及使用磁共振波谱进行光谱参数测量。为了进一步研究脂肪组织在微观水平上的相变，在对同一组织中采集的一小块脂肪进行相同的冷却/加热程序的同时，对其进行光学相干断层扫描（OCT）成像。对于所有方法，它们与温度的关系在一个狭窄的范围内呈现出拐点，这是脂质相变的特征。特别是，DSC 和光学测量之间的良好一致性表明，这种 NIRS 方法可用于改进剂量学并最小化冷冻程序的临床结果的变化。
