Specific PET scan for TB for more effective treatment

A more accurate way to scan for tuberculosis has been developed by researcher based in the U.K. and the U.S. using positron emission tomography (PET).

The team has developed a new radiotracer, which is taken up by live TB bacteria in the body. Radiotracers are radioactive compounds which give off radiation that can be detected by scanners and turned into a 3D image. The new radiotracer, called FDT, enables PET scans to be used for the first time to accurately pinpoint when and where the disease is still active in a patient’s lungs.

The researchers have put the new radiotracer through extensive pre-clinical trials with no adverse effects and it is now ready to go into Phase I trials in humans. The study has been published in the journal Nature Communications.

Currently, two methods exist for TB diagnosis: testing for the TB bacteria in a patient’s sputum using smear microscopy or a molecular test. The other is the use of a PET scan to look for signs of inflammation in the lung, using the common radiotracer FDG.

While a sputum test can show a negative long before the disease has been fully treated in the lungs, which could result in patients finishing treatment too early, scanning for inflammation can be helpful in seeing the extent of the disease, but it is not specific to TB, as inflammation can be caused by other conditions. Inflammation can also persist in the lung after the TB bacteria has been eliminated, leading to treatment continuing longer than necessary.

The new approach developed by the researchers is more specific as it uses a carbohydrate that is only processed by the TB bacteria. A key advantage of the new approach is that it only requires a hospital to have standard radiation control and PET scanners, which are becoming more widely available throughout the world. The new molecule is created from FDG using a relatively simple process involving enzymes developed by the research team. This means it can be produced without specialist expertise or laboratories and so would be a viable option in low- and middle-income countries with less developed healthcare systems. These countries currently see over 80% of global TB cases and deaths from the disease.