Researchers at the University of Texas at Arlington are using an unusual tool: NASA-inspired lower body negative-pressure (LBNP) pants, to enhance how cardiac stress tests are performed inside MR machines.

Typically, patients undergoing exercise stress testing in an MR scanner lie flat, a position that increases blood flow back to the heart. This artificially elevated stroke volume can obscure heart dysfunction and limit the test’s diagnostic value.

To address this, Michael Nelson, an associate professor at UTA, and his team adapted LBNP pants, originally designed to simulate gravity’s effects on astronauts in space, to replicate upright posture inside the MR. The pants reduce pressure in the lower body, limiting blood return to the heart and producing a more realistic cardiovascular response during exercise imaging.
“We’ve completely transformed the way we look at exercise cardiac MR,” Nelson said. “In my opinion, the recent developments we’ve made should become the new standard. You shouldn’t be doing exercise cardiac MR without lower body negative-pressure pants.”

The technology is currently patent-pending and is part of a broader effort by UTA to refine noninvasive cardiac diagnostics.

In a related development, the team has demonstrated that MR can measure venous oxygen saturation without inserting a catheter into the inferior vena cava. This method allows for safer, repeatable assessments of how much oxygen a person’s body uses during exercise — data that can help predict health risks. Findings from this work were recently published in the American Journal of Physiology and the European Heart Journal.

The research is being conducted at UTA’s $6.2 million Clinical Imaging Research Center, which features a 3-Tesla MR system designed to accommodate exercise protocols.

“We’ve eliminated a lot of the risks since it’s noninvasive and there’s no ionizing radiation,” said Mark Haykowsky, a senior investigator from the University of Alberta and former UTA professor.

Researchers say the ultimate goal is to better understand and treat exercise intolerance, a key predictor of disease and mortality.

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