A Correlational Study of THz and MRI Hydration Mapping in In vivo Skin Burns

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DESCRIPTION (provided by applicant): This proposal aims to compare terahertz (THz) reflectivity maps and MRI hydration indicators, specifically changes in T2 relaxation times, to validate tissue water content as the dominant contrast mechanism in THz burn imaging and study differences in THz imagery of partial and full thickness burn pathophysiology for early and accurate diagnosis of wound severity. Burn extent is most often examined by visual and tactile assessment with successful prognosis in only 50-70% of cases. Several burn treatment centers have implemented Laser Doppler Imaging (LDI) as a complementary diagnostic; however, this procedure relies on measurements of blood perfusion which can be a poor marker immediately following thermal insult. Preliminary in vivo results acquired by our group in rats suggest that ou non-invasive THz imaging system rapidly and accurately generates skin reflectivity imagery of burns; clearly delineating burn wound zones and burn severity within the first few hours of injury. Resultant changes in the optical properties of tissue by burn induction create contrast between injured and uninjured areas evident in acquired reflective THz images. However, THz reflectivity values around the burn region may often be spatially and temporally variable, and these findings do not always correlate with histological analysis. Given its advantages in tissue specificity and water sensitivity, MRI can be used as a supplementary tool to further understand and substantiate what appear to be hydration changes in THz maps of burn pathophysiology and reinforce the clinical potential of medical THz imaging as a point-of-care technology for rapid detection of burn wounds. Recent T2 weighted multi slice multi echo (T2w MSME) 7 Tesla MR and THz parallel imaging studies in in vivo rat skin demonstrate that both modalities can be used to localize the burn region and detect water movement in tissue; T2 relaxation times, a common MR index of hydration, and THz reflectivity measurements of the burn area increase following burn induction. These preliminary results appear to support the sufficiency of the sensitivity and specificity of MRI for measuring tissue water content and the use of this modality to verify the hydration sensing capabilities of THz burn imaging for acute diagnosis of skin burns and monitoring of edematous responses. This study will commence with pilot, parallel MRI and THz in vivo skin imaging experiments, providing the necessary groundwork for large scale in vivo rat studies. Year 2 will encompass extensive work on 20 live rats, a sample size based on a paired t-test with a power of 0.9 and a confidence interval of 0.05. Correlations between these modalities will be assessed by co-registration with histological analysis.