Magnetic resonance lung function – a breakthrough for lung imaging and functional assessment? A phantom study and clinical trial

Abstract

Background: Chronic lung diseases are a major issue in public health. A serial pulmonary assessment using imaging techniques free of ionizing radiation and which provides early information on local function impairment would therefore be a considerably important development. Magnetic resonance imaging (MRI) is a powerful tool for the static and dynamic imaging of many organs. Its application in lung imaging however, has been limited due to the low water content of the lung and the artefacts evident at air-tissue interfaces. Many attempts have been made to visualize local ventilation using the inhalation of hyperpolarized gases or gadolinium aerosol responding to MRI. None of these methods are applicable for broad clinical use as they require specific equipment.

Comparative evaluation of chest radiography, low-field MRI, the Shwachman-Kulczycki score and pulmonary function tests in patients with cystic fibrosis

“…In the second approach, low-field imaging is performed at or below 0.5 Tesla in which susceptibility artifacts are within acceptable ranges due to the lower field strength. The limited signalto-noise ratio is balanced by thicker slices of up to 55 mm [16]. Since the information contained in thick slices is averaged into one image, this technique is, to a certain extent, more comparable with radiography, where all the information is averaged into one image.…”

“…The major advantage of high-field MRI is the possibility to assess structural information together with functional information, e.g., local ventilation, in one examination [16,35], thereby reducing imaging costs and increasing patient compliance. In two recent studies, hyperpolarized 3-helium MRI has been successfully investigated in comparison with PFT in children [36] and in comparison with spirometry and high-resolution CT in adults [37].…”

“…However, it has been shown that, when using a low-field strength of 0.2 Tesla, the T2* decay is significantly slower than with imaging at 1.5 Tesla [13]. Various authors [14][15][16] have proposed different sequences at 0.2 Tesla for lung imaging. When compared with true FISP imaging (fast imaging in steady-state precession) [17], the CISS (constructive interference in steady-state precession) sequence proved slightly more advantageous with respect to pixel resolution and the detection of lung pathology.…”

Assessment of Regional Lung Function with Multivolume1H MR Imaging in Health and Obstructive Lung Disease: Comparison with3He MR Imaging

“…The use of proton MR imaging has historically been hampered by the combination of low proton density and short T2* of lung tissue (14,15), but it has regained attention with the development of short-acquisition-time techniques (16,17) and frequency-swept nuclear MR (18). Enhanced techniques developed with free-breathing MR imaging have been proposed to assess regional ventilation by using Fourier decomposition (19,20) and by using image registration (21,22).…”

Ultrashort echo time (UTE) MRI of the lung: Assessment of tissue density in the lung parenchyma

“…Bankier et al described multiple inversion recovery turbo spin‐echo sequence with the shortest possible TE (4.2 msec) for imaging human lungs and demonstrated that the gravity‐dependent gradients of MR signal changed in different postures, in which the signal represented the parenchymal tissue/blood density (19). Using a true fast imaging with steady state precession with TE of 2 msec, Zapke et al reported that the quantification of the change in the parenchymal signal during respiratory cycle could be a diagnostic tool for the pulmonary disorders (20). Recently, Failo et al showed the correlation in diagnostic quality between “very‐short” pulse repetition time (TR)/TE (TE of 800 μsec) two‐dimensional steady state free precession MRI and CT in patients with cystic fibrosis (21).…”