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

Abstract

BackgroundAlthough ultrashort echo time (UTE) sequences allow excellent assessment of lung parenchyma, image quality remains lower than that of computed tomography (CT).PurposeTo investigate a high‐frequency noninvasive ventilation (HF‐NIV) technique allowing a stabilized inspiration and to compare image quality with current dedicated MR sequences.Study TypeProspective.PopulationTen healthy volunteers.Field Strength/Sequence3D radial UTE sequence at 1.5T.AssessmentUTE‐HF‐NIV sequence was compared with UTE‐free‐breathing (UTE‐FB), reconstructed at end expiration (UTE‐Exp) and average (UTE‐Avg), and breath‐hold VIBE sequences. The distance from lung apex to the dome of the right hemidiaphragm was measured. Visual assessment of the visibility and sharpness of normal anatomical structures was carried out. Dedicated software also quantitatively evaluated vessel–lung and right lung–liver interface sharpness. Apparent signal ratio (Sr) and contrast ratios (Cr) were quantitatively evaluated.Statistical TestsWilcoxon signed rank test for visual scores, paired t‐test for continuous variables, significance at P < 0.05.ResultsThe distance between apex and the right hemidiaphragmatic dome was significantly larger (P < 0.001) with UTE‐HF‐NIV compared with UTE‐FB and VIBE acquisitions. Vessel and airway visibility had identical median visual scores with all UTE methods. Median visual scores for sharpness of vessels and airways were significantly higher (P < 0.001) with HF‐NIV (vessels = 3; airways = 2) than in UTE‐FB (vessels = 2; airways = 1) and VIBE (vessels = 1; airways = 1). Software‐based vessel sharpness evaluation resulted in larger values in 8/10 volunteers with UTE‐HF‐NIV (67.3 ± 9.8) compared with UTE‐Avg (62.3 ± 12.6) but the average difference was not significant (P = 0.28). The sharpness of the lung–liver interface was significantly higher (P < 0.001) with HF‐NIV (17.3 ± 5.3) compared with UTE‐Avg (14.1 ± 3.9). Significantly higher values (P < 0.01) of Sr and Cr were observed with UTE‐HF‐NIV compared with UTE‐FB and VIBE.Data ConclusionHF‐NIV allowing acquisition at full inspiration significantly improves image quality for lung imaging. This could offer the option to alternate some follow‐up CT studies by using this technique. Level of Evidence: 2 Technical Efficacy: Stage 1J. Magn. Reson. Imaging 2019;50:1789–1797.

Comparison Between Magnetic Resonance Imaging and Computed Tomography in the Detection and Volumetric Assessment of Lung Nodules: A Prospective Study

“…The HF-NIV was performed on patients with a Monsoon III ventilator (Acutronic Medical Systems, Hirzel, Switzerland) and a non-invasive patient interface (Phasitron, Percussionnaire, Idaho, USA) ( 14 ), according to a set-up described in Delacoste et al ( 9 ). The oxygen delivery has been set to 100% at the monitor.…”

“…Moreover, given that acquisition at full lung volume is of major importance for optimized management of indeterminate pulmonary nodules, a study has been investigating the combination of a high-frequency noninvasive ventilation (HF-NIV) technique that allows an apnea-like respiratory stabilization of several minutes at full lung volume with lung MRI. The higher image quality provided by MR images acquired under HF-NIV vs. without has been recently demonstrated in healthy volunteers ( 9 ). Several MR sequences such as UTE Spiral VIBE (volumetric interpolated breath-hold examination) without and with correction and 3D radial UTE have also been investigated under HF-NIV and the later was the sequence that would provide the highest image quality scores ( 9 , 10 ).…”

“…The higher image quality provided by MR images acquired under HF-NIV vs. without has been recently demonstrated in healthy volunteers ( 9 ). Several MR sequences such as UTE Spiral VIBE (volumetric interpolated breath-hold examination) without and with correction and 3D radial UTE have also been investigated under HF-NIV and the later was the sequence that would provide the highest image quality scores ( 9 , 10 ).…”

The current status and further prospects for lung magnetic resonance imaging in pediatric radiology

“…This also applies to older children with limited lung function [14]. Therefore only sequences that are acquired in expiration with different trigger techniques [15] or that have recently been offered as "self-gated sequences" can be considered [16].…”

Phase‐cycled balanced SSFP imaging for non‐contrast‐enhanced functional lung imaging

“…Functional lung imaging is of great importance for diagnosis and follow‐up of prevalent lung diseases 1,2 . To this end, novel non‐contrast‐enhanced MRI methods have been proposed to acquire regional pulmonary functions as well as morphological information without the use of ionizing radiation, 3,4 such as Fourier decomposition (FD), 5,6 self‐gated non‐contrast‐enhanced functional lung imaging, 7 perfusion‐weighted phase‐resolved functional lung, 8 or ultrashort TE–based techniques 9–12 …”