Keywords:
Experimental, Not applicable, Tissue characterisation, Technical aspects, CT, Animal (veterinary) studies, Performed at one institution
Authors:
S. Mizukami, H. Hara, D. Hatakeyama, E. Kanai, D. Yokoyama, H. Muraishi, T. Gomi; Sagamihara, Kanagawa/JP
DOI:
10.26044/ecr2020/C-07853
Results
Fig. 7 shows the CT-Temp conversion table of the histological samples, and Fig. 8 shows the first order approximation of the CT-Temp conversion table. In all samples, CT value decreased with increasing temperature (Thermal sensitivity: -0.2 to -1.3 HU/°C) between 5 and 60 °C. However, between -20 and -5 °C, liver, kidney, and muscle CT values increased with the increasing temperature (Thermal sensitivity: 0.6 to 1.4 HU/°C), but fat decreased (Thermal sensitivity: -0.6 HU/°C). At around -5 ° C, liver, kidney, and muscle containing much water showed increased CT value due to negative thermal expansion. However, when cooled to around -20 ° C, the CT value approached a nearly constant value.
In the living swine, CT value of liver at 36.6 °C was 55.6 HU, kidney at 36.8 °C was 39.7 HU, muscle at 35.7 °C was 55.6 HU and fat at 35.5 °C was -93.6 HU. CT values of living organs did not match on CT-Temp conversion tables of the samples (Fig. 9). So living organ CT-Temp conversion tables were obtained by parallel shifting the sample tables to living organ CT values (Fig. 10). In this study, the temperature sensitivity of the sample was reflected because the temperature of the swine living body was not changed. Further study using thermal treatment is needed in animal experiments.
Fig. 11 shows the temperature maps of samples at -10 °C, 20 °C, 50 °C. These were roughly reflected the temperature distribution. The edge of samples was shown as high temperature because of diffusion of heat and low CT value due to partial volume effect. The sample maps using a look-up table at 5 °C intervals were low noise images.
Fig. 12 and Fig. 13 show the temperature maps of living swine at liver and kidney level. These were also roughly reflected the temperature distribution. However these maps were slightly noisy. To evaluation of detailed temperature information, the noise reduction techniques must be used. Moreover, swine living body has a plurality of organs, so it is necessary to perform a segmentation of organs and convert CT value into temperature information. Real time acquisition of temperature maps requires the introduction of auto-segmentation technology.