Changes in birefringence as markers of thermal damage in tissues

Abstract

Light microscopy using polarized transmission illumination of routinely stained histologic sections shows changes of the native birefringence of certain tissue constituents when heated by laser irradiation or electrosurgical current. The naturally occurring birefringence of cardiac muscle disappears permanently when the muscle is frozen, thawed, and heated to temperatures in excess of 42 degrees C in vitro. This loss of birefringence is produced with temperatures at which other morphologic thermal changes are hard to detect; thus, it is a low-temperature tissue marker which can be used to observe the extent of thermal damage in tissues. Partial loss of the native birefringence of collagen occurs in canine urinary bladder coagulated by laser irradiation and pericardium heated with electrodes. In addition, thermally coagulated collagens have variable birefringence color shifts when compared to the adjacent unaffected collagens in stained histologic sections. The gradual birefringence color changes are seen at tissue temperatures higher than those at which the thermally induced hyalinization (coagulation) of collagen usually occurs (about 60-70 degrees C), but below those at which carbonization is seen (200+ degrees C). Birefringence changes can be measured to test mathematical models of thermal damage necessary for development of dosimetry models in medical applications of laser irradiation.

Pathologic Analysis of Photothermal and Photomechanical Effects of Laser–tissue Interactions

“…Video recordings have been correlated with light microscopic observations of laser coagulation and ablation lesions to study water-dominated mechanisms of tissue damage (LeCarpender et al, 1990;Verdaasdonk et al, 1990;Thomsen, S. and W-F. Cheong, unpublished data). These studies suggest that increased subsurface heating produces hot pockets of superheated steam and tissue constituents that influence the progression and distribution of thermal injury.…”

Applicator for RF Thermokeratoplasty: Feasibility Study Using Theoretical Modeling and Ex Vivo Experiments

“…Table 4 This could be due to the fact that the A and ∆E parameters used in the formulation of the thermal damage model correspond with the birefringence loss in the coagulated tissue (Pearce et al 2005), whereas the H&E color change boundary was used to assess the experimental lesions. This makes sense, as the loss of birefringence occurs at lower temperatures than other histological markers (Thomsen et al 1989).…”

“…Similar behavior can be inferred from This study has certain limitations. Firstly, the experimental method used to assess lesion dimensions was routine light microscopy, which does not allow high-resolution observation of some morphological changes, as opposed to other techniques such as transmission polarizing microscopy (Thomsen et al 1989). Secondly, the parameters A and ∆E used in the formulation of the thermal damage model correspond with birefrigence loss in coagulated tissue (Pearce et al 2005).…”

Three Dimensional Comparison of Interventional MR Radiofrequency Ablation Images with Tissue Response

“…Upon thermal injury, a loss of birefringence occurs due to the disarray of the regular matrix of the actin and myosin molecules, and this has been previously shown to correspond to a region of eventual necrosis [5].…”

“…Using the video microscopy system and software program, we determined the location of tissue damage boundaries on the slide, and marked the appropriate position on the map image. Cellular damage was defined by a loss of muscle's naturally occurring birefringence, which has been shown to be a reliable indicator of irreversible cell damage [5]. Birefringence properties were determined by examining the slide under polarized light.…”