Ventilation Percussion Improves Cardiac MRI Accuracy

Developed at University Hospital Lausanne (CHUV; Switzerland), the percussive ventilation (VP) technique involves the patients wearing a mask over their mouth, which is connected to a ventilator that delivers small volumes of air (percussions). Instead of the 10-15 large breaths patients would take naturally per minute, air is provided in 300-500 small VP pulses per minute. The air volumes inhaled are so small the chest does not move, allowing acquisition of higher quality images in less time.

In a study designed to test the feasibility and tolerability of high frequency PV during CMR, the researchers recruited two patients, one healthy volunteer and one patient with a thymic lesion. The procedure was well tolerated, and there was no need to correct for respiratory motion. Lung volumes were "frozen" in full inspiration, allowing the researchers to see both coronary arteries and pulmonary vessels. The study was presented at EuroCMR, held during May 2016 in Florence, Italy.

“The possibilities with high frequency PV are huge. You could run all the CMR sequences in one batch, which would be much faster; data could be acquired constantly with fewer artifacts,” said lead author and study presenter Professor Juerg Schwitter, MD, director of the CHUV CMR Centre. “We might be able to use this technique for diagnosis of sicker patients, who find breath holding difficult and need the imaging to be done quickly.”

"This technique would help us to collect high resolution images where we want millimetric precision, for example to localize scar in the myocardium or to see the anatomy of coronary arteries or valves and malformations,” added Professor Schwitter. “We could even imagine that if the patient is not breathing for 20 minutes, or even longer, this technique could give a precise 3D representation of cardiac structures and help guide electrophysiology procedures such as ablation."

CMR is a medical imaging technology for the non-invasive assessment of the function and structure of the cardiovascular system that is based on the same basic principles as magnetic resonance imaging (MRI), with optimizations that use rapid imaging sequences. As a result, CMR images are currently acquired in steps. Patients breathe in and then hold their breath for each image, then recover before repeating the process for the next image. PV could offer the potential to acquire all images in one go, with no need to correct for respiratory motion.

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