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Detecting Pulmonary Blood Clots With Portable Device

Noninvasive technique uses electrical currents to probe impedance changes

Electrical-engineering researchers at the University of Sydney in Australia are developing new technology to safely diagnose blockages in lung arteries in real time.

The results of a 3-year project investigating an alternate method for diagnosing pulmonary embolism (PE) that combines electrical impedance tomography (EIT) and a saline-based contrast solution were published in the Journal of Physiological Measurement.

Lead author Trang Nguyen, a PhD candidate, said the team was focused on developing a portable, radiation-free, nontoxic device to replace the current invasive procedure, which relies on methods such as computed tomography (CT) pulmonary angiograms. Regarding the latter technology, Nguyen remarked: “This approach exposes a patient to ionizing radiation and nephrotoxic contrast agents. It also requires a patient to be moved to a dedicated imaging chamber, which is far from ideal for critically ill patients.”

“EIT is an emerging clinical tool. It is a noninvasive medical imaging technique that uses electrical currents to probe impedance changes within the body,” Nguyen explained.

“Ventilation and perfusion are two sides of the same coin. We started from the premise that in order to understand the physiological state of the patient’s lungs, both ventilation and pulmonary perfusion information are required. We were particularly motivated by the possibility of using EIT for diagnosis of PE [pulmonary embolism],” she added.

The investigators concluded that EIT can reliably detect the difference between normal and embolized lungs with a one-sided perfusion defect. They pointed out, however, that a larger trial is required before the method can be used clinically for the diagnosis of PE.

“While PE can lead to severe and possible long-term damage of the cardiovascular system, its symptoms are highly unspecific,” said senior author Dr. Alistair McEwan. “As EIT is less invasive and does not use radiation, we are hopeful that it can be used as a first-stop imaging diagnosis for PE before a CT pulmonary angiogram is prescribed, to reduce radiation and contrast exposure in patients.”

“Understanding these properties will enable us to better address a range of major health challenges relating to cardiovascular disease, cancer, and nutrition,” he said.

Sources: University of Sydney; June 10, 2015; and MedicalPhysicsWeb; June 3, 2015.

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