Pakarinen Tomppa, Joutsen Atte, Oksala Niku, Vehkaoja Antti
Faculty of Medicine and Health Technology, Tampere University, Postal: Tampereen Yliopisto, Korkeakoulunkatu 3, 33720, Tampere, Finland.
Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Postal: Sädetie 6, 33520, Tampere, Finland.
J Therm Biol. 2023 Feb;112:103467. doi: 10.1016/j.jtherbio.2023.103467. Epub 2023 Jan 12.
Current chronic limb threatening ischemia (CLTI) diagnostics require expensive equipment, using ionizing radiation or contrast agents, or summative surrogate methods lacking in spatial information. Our aim is to develop and improve contactless, non-ionizing and cost-effective diagnostic methods for CLTI assessment with high spatial accuracy by utilizing dynamic thermal imaging and the angiosome concept.
Dynamic thermal imaging test protocol was suggested and implemented with a number of computational parameters. Pilot data was measured from 3 healthy young subjects, 4 peripheral artery disease (PAD) patients and 4 CLTI patients. The protocol consists of clinical reference measurements, including ankle- and toe-brachial indices (ABI, TBI), and a modified patient bed for hydrostatic and thermal modulation tests. The data was analyzed using bivariate correlation.
The thermal recovery time constant was on average higher for the PAD (88%) and CLTI (83%) groups with respect to the healthy young subjects. The contralateral symmetry was high for the healthy young group and low for the CLTI group. The recovery time constants showed high negative correlation to TBI (ρ = -0.73) and ABI (ρ = -0.60). The relation of these clinical parameters to the hydrostatic response and absolute temperatures (|ρ|<0.3) remained unclear.
The lack of correlation for absolute temperatures or their contralateral differences with the clinical status, ABI and TBI disputes their use in CLTI diagnostics. Thermal modulation tests tend to augment the signs of thermoregulation deficiencies and accordingly high correlations were found with all reference metrics. The method is promising for establishing the connection between impaired perfusion and thermography. The hydrostatic modulation test requires more research with stricter test conditions.
目前慢性肢体威胁性缺血（CLTI）的诊断需要使用电离辐射或造影剂的昂贵设备，或者缺乏空间信息的汇总替代方法。我们的目标是通过利用动态热成像和血管体概念，开发和改进用于CLTI评估的非接触式、非电离且经济高效的诊断方法，以实现高空间精度。
提出并实施了具有多个计算参数的动态热成像测试方案。从3名健康年轻受试者、4名外周动脉疾病（PAD）患者和4名CLTI患者中测量了试点数据。该方案包括临床参考测量，包括踝肱指数（ABI）和趾肱指数（TBI），以及用于静水压和热调节测试的改良患者床。使用双变量相关性分析数据。
与健康年轻受试者相比，PAD组（88%）和CLTI组（83%）的热恢复时间常数平均更高。健康年轻组的对侧对称性高，而CLTI组的对侧对称性低。恢复时间常数与TBI（ρ = -0.73）和ABI（ρ = -0.60）呈高度负相关。这些临床参数与静水压反应和绝对温度的关系（|ρ|<0.3）仍不清楚。
绝对温度或其对侧差异与临床状态、ABI和TBI缺乏相关性，这对它们在CLTI诊断中的应用提出了质疑。热调节测试往往会加剧体温调节缺陷的迹象，因此发现与所有参考指标都有高度相关性。该方法有望建立灌注受损与热成像之间的联系。静水压调节测试需要在更严格的测试条件下进行更多研究。
