Focal dynamic thermal imaging for label-free high-resolution characterization of materials and tissue heterogeneity

Abstract

Evolution from static to dynamic label-free thermal imaging has improved bulk tissue characterization, but fails to capture subtle thermal properties in heterogeneous systems. Here, we report a label-free, high speed, and high-resolution platform technology, focal dynamic thermal imaging (FDTI), for delineating material patterns and tissue heterogeneity. Stimulation of focal regions of thermally responsive systems with a narrow beam, low power, and low cost 405 nm laser perturbs the thermal equilibrium. Capturing the dynamic response of 3D printed phantoms, ex vivo biological tissue, and in vivo mouse and rat models of cancer with a thermal camera reveals material heterogeneity and delineates diseased from healthy tissue. The intuitive and non-contact FDTI method allows for rapid interrogation of suspicious lesions and longitudinal changes in tissue heterogeneity with high-resolution and large field of view. Portable FDTI holds promise as a clinical tool for capturing subtle differences in heterogeneity between malignant, benign, and inflamed tissue.

Luminescence‐Based Infrared Thermal Sensors: Comprehensive Insights

“…Movable and non‐contact focal dynamic thermal imaging (FDTI) technique has potential of high resolution, label free and high speed in clinical diagnosis for detecting heterogeneity in malignant, benign, and inflammatory tissue. With a low power 405 nm power source and a narrow beam, 3D printed phantoms thermal imaging, mouse in‐vivo, biological tissue ex vivo, as well as rat cancer models confronts diversity of material and distinguishes infected and healthy tissue [ 215 ] (Figure 19d). Contactless FDTI approach enables fast, high‐resolution examination of worrisome lesions and alteration in tissue heterogeneity longitudinally.…”

“…d) Focal dynamic thermal imaging of one rat throughout tumor progression. Reproduced with permission, [ 215 ] Copyright 2022, Springer Nature. e) WIR‐384A uncooled infrared thermal imager.…”

Ablation of porcine subcutaneous fat and porcine aorta tissues by a burst‐mode nanosecond‐pulsed laser at 355 nm

“…Porcine subcutaneous fat [28][29][30][31] Porcine aorta [32][33][34] Absorption coefficient μ a From Figure 15A, we can see that the high temperature is limited in the area of about 1 mm away from the laser action point, and temperature increases at a slower rate as the average power increases, which is because of the higher advancement rate of fiber bundle when porcine subcutaneous fat is irradiated by laser with higher average power and melting point of porcine subcutaneous fat (95 C) [35]. Tissue maximum temperature as a function of irradiation time varying from 2 to 10 s with average power kept at 2.537 W is shown in Figure 15B.…”

Application of the Machine Vision Technology and Infrared Thermography to the Detection of Hoof Diseases in Dairy Cows: A Review

“…Resolution of Thermal Images [64] 60 × 80 (0.005 MP) [65,66] 160 × 120 (0.019 MP) [67][68][69][70][71][72][73][74][75][76][77][78][79][80] 320 × 240 (0.077 MP) [63,81,82] 320 × 256 (0.085 MP) [83,84] 336 × 256 (0.086 MP) [85,86] 384 × 288 (0.111 MP) [59][60][61][62][87][88][89][90][91][92][93][94] 640 × 480 (0.307 MP) [95,96] 640 × 512 (0.328 MP)…”

“…If a neuron's threshold is reached, i.e., if the sum of the products of the input values with the corresponding synaptic weights is equal to or greater than this value, the output signal of the neurons is produced by an activation function whose prescription is the same for all neurons in a single layer. Within multiple layers, the activation functions may differ, for example, in [72], a three-layer neural network with different activation functions was presented, applying a hyperbolic tangent function for the hidden layer and a linear function for the output layer. In contrast, both Gang et al and Wu chose the same activation function, the standard (logistic) sigmoid function, for the hidden and output layers [104,115].…”