Researchers at Kyushu University have developed a seven-second X-ray scan that can detect a common heart complication after Tetralogy of Fallot surgery with 93% accuracy, according to a study published in the journal Radiology.
The technique uses dynamic chest radiography (DCR), a method that relies on standard X-ray equipment to capture sequential images while the patient holds their breath. It is designed to evaluate pulmonary valve regurgitation, a condition where blood leaks backward into the right ventricle after each heartbeat.
Tetralogy of Fallot, or TOF, affects roughly 1 in 3,500 newborns and is the most common cyanotic congenital heart defect. The condition involves structural problems that reduce blood flow to the lungs, leading to low oxygen levels.
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Why monitoring matters after TOF repair
Thanks to improved surgical techniques, more than 90% of TOF patients now survive into adulthood. Yet pulmonary regurgitation remains a frequent long-term complication.
“Pulmonary Regurgitation is a common long-term complication after surgical repair that can lead to increased risk of sudden cardiac arrest if left untreated,” said Assistant Professor Yuzo Yamasaki of Kyushu University Hospital Radiology Center, the study’s first author. “Monitoring PR severity is essential to determine when patients should be treated.”
Cardiac MRI is currently the standard method for measuring PR severity. But MRI scans are expensive, require specialized equipment, and cannot be used on patients with incompatible pacemakers, defibrillators, or severe claustrophobia.
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How the new scan works
Instead of relying on visual assessment of DCR images, the researchers analyzed changes in pixel values over the pulmonary arteries across the sequential images. Those changes were converted into waveforms that reflect blood flow.
“In patients with PR, blood flows back into the right ventricle during each heartbeat. The more severe the regurgitation, the more blood flows and that shows up as a more prominent waveform,” Yamasaki said.
They tested the technique on 58 post-surgical patients and 14 healthy volunteers. Severe PR was detected with 93% accuracy.
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Radiation and cost advantages
Because DCR uses X-ray technology, it requires no contrast media and exposes patients to roughly 0.2 mSv of radiation. A standard chest CT delivers around 6 mSv.
The approach could expand access to accurate diagnosis for patients who cannot tolerate MRI, while also reducing costs for hospitals. The team thinks the technique may have applications beyond PR. “DCR can also be used to study and diagnose other heart diseases like heart failure and pulmonary hypertension,” Yamasaki noted.
The group is now planning a multicenter study to validate the findings further, with the goal of establishing DCR in routine clinical practice. The study was conducted at Kyushu University Hospital.