Novel MR-based test shortens sepsis detection time

2016 08 09 13 53 34 187 T2 Dx Instrument 2015 400

A Massachusetts start-up has developed a tabletop device that uses MR technology to scan blood samples from patients with a suspected sepsis infection. The company, T2 Biosystems, hopes its technology will speed the use of targeted treatment for sepsis patients, enhancing clinical outcomes and reducing hospital costs.

The novel T2MR nanotechnology works on the same principle as diffusion-tensor MRI. Rather than acquiring an MR image, the company's T2Dx scanner examines blood samples to provide a T2 value, which measures how water molecules react in the presence of magnetic fields to identify infection in a blood sample. In this case, a high T2 value indicates the presence of a certain pathogen.

"Our [U.S. Food and Drug Administration (FDA)] clinical trial data shows that we detect [sepsis in] more than 90% of patients, whereas blood culture studies are detecting only 60% to 70%," said T2 Biosystems CEO John McDonough. "Not only is there a huge labor and time advantage with our system, but we are detecting more patients with sepsis."

Severity of sepsis

Sepsis is a severe blood infection that can cause organ deterioration and death, if not treated quickly and properly. It can be caused by a simple accident such as a scraped knee or cut to the skin, or result from a more serious condition such as pneumonia, meningitis, or a urinary tract infection, according to WebMD.

T2 Biosystems CEO John McDonough.T2 Biosystems CEO John McDonough.

The U.S. Centers for Disease Control and Prevention (CDC) estimates there are more than 1 million cases of sepsis in the U.S. each year, and more than 258,000 Americans die from the infection, making it the ninth-leading cause of disease-related death in the country. As many as 50% of survivors have postsepsis syndrome and damaged organs, according to the CDC.

Sepsis is also the most expensive hospital-treated condition and accounts for more than $20 billion in annual costs for U.S. healthcare systems, based on numbers from the U.S. Department of Health and Human Services.

A 2013 study by Neely et al in Science Translational Medicine found that the average in-hospital stay for a patient with sepsis is 40 days. Recovery time includes an average of nine days in an intensive care unit and a total average cost to the facility of more than $130,000 per patient.

"In the meantime, people are being blasted by drugs and many of them don't need it," McDonough added. "Data shows that if patients get on the right drug sooner, that mortality rate can be cut in half or better."

Research roots

T2 Biosystems' roots go back to research conducted at the Massachusetts Institute of Technology (MIT) and Massachusetts General Hospital in Boston. Given the promise of the technology, capital was raised from several Boston-based venture firms to create the company and commercialize the test.

T2MR technology requires that only 2 mL of blood be drawn from the patient for scanning in the T2Dx system, a device about the size of a desktop computed radiography (CR) reader. The T2Dx process adds superparamagnetic particles to the blood sample that are designed to bind to certain pathogens, such as Candida, a type of fungus that can cause sepsis. If the targeted pathogens are present, the particles will bind to them and cluster, changing the magnetic properties of the water molecules in the blood sample.

"We rely on the same basic principles behind MRI to measure how long these water molecules have been in their rate of decay during the measurements," explained Tom Lowery, PhD, T2 Biosystems' chief scientific officer. "The nuclei of the water molecules are very sensitive to their microenvironment. Like a weighted MR image, T2 will be brighter or dimmer if the T2 value is higher or lower based on the microenvironment of the water in the sample."

Thus, a higher T2 value indicates a positive result and the presence of the pathogen, while a low T2 number indicates a negative result. The test takes only three to five hours to complete, compared with a blood culture that can take three to five days and also generally requires more than twice as much blood for a sample.

The T2Dx device uses the company's T2MR technology to scan blood samples drawn from patients. Image courtesy of T2 Biosystems.The T2Dx device uses the company's T2MR technology to scan blood samples drawn from patients. Image courtesy of T2 Biosystems.

The quick availability of the results is critical, McDonough said, as previous studies have found that for every hour of delayed treatment for sepsis, mortality increases by approximately 8%. Knowing the correct species of infection can lead to a patient receiving the right treatment.

The company's T2Candida panel, which detects five species of Candida, received 510(k) clearance from the FDA last year after clinical trials reported overall sensitivity of 91% and specificity of 99%.

Future targets

More current customer feedback suggests the T2MR technology is having a positive effect on patients' length of stay from sepsis, with fewer days in the intensive care unit, lower mortality, and reduced hospital costs, McDonough said.

As of the end of June, T2 Biosystems had contracts with approximately 100 hospitals in the U.S. and in three European countries. The company launched its T2Candida panel in Europe earlier this year after receiving CE Mark regulatory approval. T2 Biosystems also has some 50 issued patents and another 50 patents pending around the world.

In addition, the company has several other T2MR applications in development. The next product would target several types of bacteria, such as E. coli, that also are currently only detected through days-long testing of blood cultures. The panel is planned for marketing as soon as next year, subject to FDA clearance.

The company is also developing a T2Lyme panel for Lyme disease, which is caused by the infiltration of bacteria into the bloodstream. The CDC estimates that as many as 90% of people with the condition are not correctly diagnosed.

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