Recently, a positive association was found between outdoor temperature and glycated hemoglobin (HbA1c), 17 indicating that systemic glucose homeostasis is influenced by environmental temperature. 14–16 Considering the putative role of BAT in the control of insulin action, combined with the effect of ambient temperature on BAT activity, we hypothesized that the global increase in temperature contributes to the current type 2 diabetes epidemic. It has previously been shown that BAT activity is negatively associated with outdoor temperature and is highest in winter. 12 It is conceivable that an increased flux of fatty acids toward BAT will result in a compensatory increased flux of glucose to other metabolically active tissues, thereby improving systemic insulin sensitivity. 11 A recent landmark paper showed that acclimatization of patients with type 2 diabetes to moderate cold for only 10 days already improved insulin sensitivity as determined by a markedly higher glucose infusion rate during a hyperinsulinemic–euglycemic clamp, while body weight was unaltered. 9 10 Indeed, prolonged cold acclimatization recruits BAT activity 10 and is able to induce modest weight loss. 8 Physiologically, BAT is activated by cold exposure. Recently, brown adipose tissue (BAT) has emerged as an organ that is capable of combusting large amounts of lipids to generate heat. 6 Interestingly, a very low-calorie diet can rapidly diminish steatosis and insulin resistance independent of weight loss 7 indicating dissociation between insulin resistance and obesity perse. 3–5 For example, South Asians are prone to develop type 2 diabetes at a relatively low BMI, presumably because of the limited lipid storage capacity of their adipose tissue depots. 3 The variability in the degree of steatosis and the heterogeneity of body fat distribution over subcutaneous and visceral fat depots probably explains the only modest association between measures of overall body fat and insulin resistance. However, according to the lipid overflow hypothesis, when the storage capacity of adipose tissue is exceeded, lipids can accumulate in organs (steatosis) including the pancreas, liver, heart and skeletal muscle, resulting in insulin resistance of those organs. With increasing body mass index (BMI), glucose and lipids are initially stored in expanding (subcutaneous) adipose tissue compartments. 1 The type 2 diabetes epidemic accompanies the increasing prevalence of obesity. 1 In high-income countries, 91% of adults affected by diabetes have type 2 diabetes. In 2015, 415 million adults globally were suffering from diabetes, and expectations are that the prevalence will rise by almost 55%, up to 642 million cases by 2040. Furthermore, several performance metrics are computed to present an aggregate overview of the proposed method advantages.The prevalence of type 2 diabetes is increasing rapidly worldwide. Several images from BRATS database with tumors anywhere in images and having different sizes, contrast, and shape, are used to test the proposed system. Equally important, for a comparison purposes, we considered different active contour models and investigated their impact on the performance of the segmentation task. As a result, this initial contour assists the algorithm to evolve an active contour model towards the exact tumor boundaries. Further, in the segmentation part, the detected initial contour is used to define an active contour model and presenting the problematic as an energy minimization problem. The simulated optical correlation, computed between Magnetic Resonance Images (MRI) and this filter, estimates precisely and automatically the initial contour inside the tumorous tissue. The tumor filter, used in the simulated optical correlation, is tailored to all the brain tumor types and especially to the Glioblastoma, which considered to be the most aggressive cancer. In the proposed method, a numerical simulation of the optical Vander Lugt correlator is used for automatically detecting the abnormal tissue region.
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