Dengue : Real Time Imaging Helps Monitor Progression of Infection

Positron emission tomography (PET) is an imaging technique where small quantities of radioactive materials, known as radiotracers, a computer and a camera are used to examine a patient’s tissues and organs. The images are used to determine the cellular changes that occur in the body and can be used for early detection of cancerous conditions. Initially this technique, combined with fluorodeoxyglucose (FDG), a glucose metabolism probe, was used to identify solid tumors by using PET. However, the procedure is gradually being considered archaic with newer and better imaging techniques becoming available.

A research team from the Singapore General Hospital (SGH) and the Duke-NUS Medical School (Duke-NUS) has shown that this imaging technique could be used to identify early onset of infectious diseases, bringing life back to this ‘old’ technique. The technique can now be used

• As an imaging tool to identify and trace the progress of dengue infections in real time
• To determine the effectiveness of a dengue treatment program

Mechanism of Function

In general PET, a radioactive material is either injected or inhaled into the body, which then accumulates in the organ or tissues. The emissions from the radiotracer are detected by a special camera and monitored on a computer. FDG is a radioactive version of glucose that can be used to track where the cells take up body glucose.

In the current study, the FDG was injected into mice. The research team knew that dengue infected mice had inflammation of the large and small intestines; this was used as a marker for detection of dengue. Inflammation resulted in an increased uptake of glucose by the cells in the intestines, which could be visualized by the PET-FDG technique.

Dr. Ann-Marie Chacko who is the lead author of the study and an Assistant Professor of Duke-NUS said that this was the first time that PET was used to determine the presence of an acute viral infection. This finding can be used to obtain quality images of dengue infection in the body using non-invasive technology.

The findings of the study included:

• Inflammation was detected in the small, large intestines and the spleen of dengue infected mice
• After anti-viral therapy was administered to the mice, the inflammation subsided
• The severity of the infection could be predicted by assessing glucose uptake by the FDG-PET

Dr. Subhash Vasudevan, who is the senior author of the study and a Professor at Duke-NUS’s Department of Emerging Infectious Diseases Programme, said that visualizing dengue infection could revolutionize the dengue treatment and care as it would help in assessing the effectiveness of treatment. The research team will soon be collaborating with scientists to improve dengue detection by utilizing this imaging procedure.

The viral load present in the blood has been the important method of measuring the severity of infection, according to Dr. Jenny Low, a senior consultant at Duke-NUS. The scientist revealed that the major factor in a clinical trial is the absence of an effective measure of treatment, which this imaging technique could solve. The various potential treatment procedures used in clinical trials for dengue can now be monitored in real time using this FDG-PET procedure, identifying the effectiveness of the treatment.

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The current findings need to be translated for application in clinical trials which will provide a better measure of effectiveness.

Dengue Infections

Dengue esults in flu-like symptoms and is a mosquito borne viral infection. It is an infectious disease which occurs in tropical and sub-tropical regions in the world. There has been an increase in the global incidence of dengue,and, since there is no cure for dengue, treatment is focused on lowering the intensity of symptoms.

Early detection of dengue is very important as it helps in lowering fatality to 1%. A lot of research is being conducted on dengue infections to identify a potential cure for the disease, although, there is no known cure till now. The PET imaging technique could be used to determine the presence of the dengue infection and for monitoring the progression of the disease, irrespective of the severity of the symptoms. This will help to identify high risk patients or can be used to determine if the infection has truly subsided or not.
References:

1. Positron Emission Tomography - Computed Tomography (PET/CT) - (https://www.radiologyinfo.org/en/info.cfm?pg=pet)
2. Dengue and severe dengue - (http://www.who.int/mediacentre/factsheets/fs117/en/)
3. Positron Emission Tomography - Computed Tomography (PET/CT) - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5414563/)

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Source-Medindia