New MRI Approach Captures Rapidly Decaying Tissue Signals

MRI measures signals generated as excited proton spins return toward equilibrium. However, some tissue signals decay so rapidly that conventional systems can miss them during the brief interval after excitation, known as receiver “dead time.” This is particularly challenging for rapidly decaying signals from tissues such as the lungs. Researchers have now developed a technique that enables excitation and signal detection to occur simultaneously, virtually eliminating measurement dead time.

Researchers at the University of Stuttgart developed a method known as concurrent excitation and detection in magnetic resonance using voltage-controlled oscillators. In conventional systems, electromagnetic energy stored in the receive coil must dissipate before the much weaker spin signal can be measured. The new approach instead shifts this stored energy to another frequency, allowing signal detection to begin even while the excitation pulse is still being applied.

Laboratory testing showed virtually no measurement dead time, according to the researchers. The frequency-shifting process occurs many orders of magnitude faster than waiting for the stored energy to decay naturally. The findings were published in Science Advances on September 16, 2026.

The researchers are now working with Ulm University Hospital to refine the method for medical applications. In collaboration with Charité in Berlin and Helmholtz-Zentrum Berlin, they are also evaluating the approach for electron paramagnetic resonance (EPR), including potential applications in skin cancer diagnosis and treatment. EPR can also be used to measure free radicals in blood samples and monitor how they break down.

Beyond medicine, the University of Stuttgart’s Materials Testing Institute is applying the technique to assess material porosity, while the Q NOVA project is exploring its use in more compact and cost-effective systems.

“During the excitation pulse, a large amount of electromagnetic energy is stored in the resonant circuit of the receive coil. By comparison, the actual spin signal is minuscule. In conventional systems, this energy must first decay before the weak spin signal can be measured again,” said Michal Kern, Group Leader at the Institute of Smart Sensors (IIS) at the University of Stuttgart and co-author of the paper. 

“With our approach, we don’t wait for it but rather shift the energy to a different frequency. This process is many orders of magnitude faster and even allows for detection during the excitation pulse. We demonstrated that this results in virtually no dead time during the measurement,” added Prof. Jens Anders, director of the IIS at the University of Stuttgart.

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