Proton MRI Based Ventilation Imaging: Oxygen-Enhanced Lung MRI and Alternative Approaches

Review of oxygen‐enhanced lung mri: Pulse sequences for image acquisition and T1 measurement

“…The T 1 differences in publications through 30 June 2016 are depicted in Dietrich's detailed review paper 26 . According to Dietrich's analyses, the weighted mean value of T 1 after breathing room air and pure oxygen was 1196 and 1054 ms, respectively, for a 118 ms or 10% reduction 16 . Based on Dietrich's research, we referenced recent publications and further summarized the T 1 values at different magnetic field strengths through June 2022 in Table 2.…”

“…Generalized autocalibrating partially parallel acquisition (GRAPPA) is beneficial in regions where coil sensitivity maps are difficult to obtain due to the local inhomogeneities and low spin density 74 . It is commonly used in IR‐HASTE for lung imaging, reducing the acquired phase‐encoding steps with a 128 × 128 matrix from 72 to 36 without sacrificing image quality and decreasing the acquisition time by approximately 50% 16,70 . Concerning the IR‐HASTE, the blurring resulting from phase encoding is reduced, while the resolution is increased 75 .…”

“…In particular, the UTE sequence is beneficial for short T 2 * tissue, 15 providing a method for measurement of the T 2 * on OE‐MRI. Additionally, parallel imaging and compressed sensing have been employed on OE‐MRI in some studies to accelerate image acquisition, 16,17 while current motion‐related lung imaging techniques, such as Fourier Decomposition, 18 have not been reported on OE‐MRI. T 1 decrease between air and oxygen conditions depends on the actual state of the diseased lung tissue so that it can be measured as an important parameter indicating lung function 19,20 .…”

“…Several review articles have described the basic concepts and clinical application of OE‐MRI, including the theory of oxygen enhancement and its relationship with pulmonary physiology and meta‐analyses of T 1 ‐relaxation time constants 6,16,24–26 . However, previous reviews have not described the pulse sequence design in detail.…”

“…22,23 Several review articles have described the basic concepts and clinical application of OE-MRI, including the theory of oxygen enhancement and its relationship with pulmonary physiology and meta-analyses of T 1 -relaxation time constants. 6,16,[24][25][26] However, previous reviews have not described the pulse sequence design in detail. This review aims to summarise and analyze imaging pulse sequences and T 1 assessment methods for oxygen-enhanced lung MRI, followed by applying dynamic and lower-field OE-MRI.…”