Chest-MRI under pulsatile flow ventilation: A new promising technique

Abstract

ObjectivesMagnetic resonance imaging (MRI) of the chest has long suffered from its sensitivity to respiratory and cardiac motion with an intrinsically low signal to noise ratio and a limited spatial resolution. The purpose of this study was to perform chest MRI under an adapted non invasive pulsatile flow ventilation system (high frequency percussive ventilation, HFPV®) allowing breath hold durations 10 to 15 times longer than other existing systems.MethodsOne volunteer and one patient known for a thymic lesion underwent a chest MRI under ventilation percussion technique (VP-MR). Routinely used sequences were performed with and without the device during three sets of apnoea on inspiration.ResultsVP-MR was well tolerated in both cases. The mean duration of the thoracic stabilization was 10.5 min (range 8.5–12) and 5.8 min (range 5–6.2) for Volunteer 1 and Patient 1, respectively. An overall increased image quality was seen under VP-MR with a better delineation of the mediastinal lesion for Patient 1. Nodules discovered in Volunteer 1 were confirmed with low dose CT.ConclusionVP-MR was feasible and increased spatial resolution of chest MRI by allowing acquisition at full inspiration during thoracic stabilization approaching prolonged apnoea. This new technique could be of benefit to numerous thoracic disorders.

MR Volumetry of Lung Nodules: A Pilot Study

“…In particular, the reliability of volume measurements close to the lung bases needs confirmation. Although the respiratory stabilization method used (21) greatly diminishes motion compared to free-breathing acquisitions, residual motion artifacts may remain, particularly at the lung bases. Related to this issue, it also remains to be ascertained that respiratory stabilization can also be reliably achieved in patients with lung disease.…”

“…We also compared the CT and UTE-MR volumetric assessment of a real nodule incidentally detected in the upper part of the right upper lobe of a volunteer from a recent study that explored a new technique allowing prolonged apnea-like MR acquisition performed at full inspiration (21). UTE acquisition was carried out during a 6-min long respiratory stabilization period.…”

Ultrashort echo time imaging of the lungs under high‐frequency noninvasive ventilation: A new approach to lung imaging

“…For each volunteer, the UTE acquisition was carried out during a 6‐minute long respiratory stabilization period. Stabilization was achieved with HF‐NIV using a Monsoon III ventilator (Acutronic Medical Systems, Hirzel, Switzerland) and a noninvasive patient interface (Phasitron; Percussionaire, Sandpoint, ID) at a respiratory rate of 250 per minute as previously published . In summary, subjects were ventilated delivering small tidal volumes, around 50 ml, at high frequency, which allows supporting gas exchange, in particular CO 2 clearing, and thus limits the need to breathe.…”

“…A technique allowing high‐resolution MRI of the lung at an end‐inspiratory volume could approach the appearance of CT, facilitating intermodality comparison, and thus make it a viable alternative in clinical practice. High‐frequency noninvasive ventilation (HF‐NIV) has been recently applied to achieve respiratory stabilization at inspiratory volume during multiple minutes for radiotherapy and an initial pilot study subsequently demonstrated the feasibility of this technique for MRI . However, a systematic evaluation of the image quality obtained with this new technique remains to be carried out.…”

“…Highfrequency noninvasive ventilation (HF-NIV) has been recently applied to achieve respiratory stabilization at inspiratory volume during multiple minutes for radiotherapy 15 and an initial pilot study subsequently demonstrated the feasibility of this technique for MRI. 16 However, a systematic evaluation of the image quality obtained with this new technique remains to be carried out. One goal of the present study was to confirm the difference in organ positions when HF-NIV was used compared with current dedicated MR sequences for lung imaging, especially at the diaphragmatic level.…”