Bioxydyn Ltd.

A method is proposed to quantify cerebral blood volume () and intravascular water residence time () using MR fingerprinting (MRF), applied using a spoiled gradient echo sequence without the need for contrast agent.

An in silico study optimized an acquisition protocol to maximize the sensitivity of the measurement to and changes. Its accuracy in the presence of variations in , , and was evaluated. The optimized protocol (scan time of 19 min) was then tested in a exploratory healthy volunteer study (10 volunteers, mean age 24 3, six males) at 3 T with a repeat scan taken after repositioning to allow estimation of repeatability.

Simulations show that assuming literature values for and , no variation in , while fitting only and , leads to large errors in quantification of and , regardless of noise levels. However, simulations also show that matching , , , and , simultaneously is feasible at clinically achievable noise levels. Across the healthy volunteers, all parameter quantifications fell within the expected literature range. In addition, the maps show good agreement between hemispheres suggesting physiologically relevant information is being extracted. Expected differences between white and gray matter (p < 0.0001) and (p < 0.0001) are observed, and show no significant differences, p = 0.4 and p = 0.6, respectively. Moderate to excellent repeatability was seen between repeat scans: mean intra‐class correlation coefficient of , , , and .

We demonstrate that regional simultaneous quantification of , , , and using MRF is feasible in vivo.

Recent years have witnessed major advances in lung imaging in patients with COPD. These include significant refinements in images obtained by computed tomography (CT) scans together with the introduction of new techniques and software that aim for obtaining the best image whilst using the lowest possible radiation dose. Magnetic resonance imaging (MRI) has also emerged as a useful radiation-free tool in assessing structural and more importantly functional derangements in patients with well-established COPD and smokers without COPD, even before the existence of overt changes in resting physiological lung function tests. Together, CT and MRI now allow objective quantification and assessment of structural changes within the airways, lung parenchyma and pulmonary vessels. Furthermore, CT and MRI can now provide objective assessments of regional lung ventilation and perfusion, and multinuclear MRI provides further insight into gas exchange; this can help in structured decisions regarding treatment plans. These advances in chest imaging techniques have brought new insights into our understanding of disease pathophysiology and characterising different disease phenotypes. The present review discusses, in detail, the advances in lung imaging in patients with COPD and how structural and functional imaging are linked with common resting physiological tests and important clinical outcomes.

Dynamic lung oxygen‐enhanced MRI (OE‐MRI) is challenging due to the presence of confounding signals and poor signal‐to‐noise ratio, particularly at 3 T. We have created a robust pipeline utilizing independent component analysis (ICA) to automatically extract the oxygen‐induced signal change from confounding factors to improve the accuracy and sensitivity of lung OE‐MRI.

Dynamic OE‐MRI was performed on healthy participants using a dual‐echo multi‐slice spoiled gradient echo sequence at 3 T and cyclical gas delivery. ICA was applied to each echo within a thoracic mask. The ICA component relating to the oxygen‐enhancement signal was automatically identified using correlation analysis. The oxygen‐enhancement component was reconstructed, and the percentage signal enhancement (PSE) was calculated. The lung PSE of current smokers was compared with nonsmokers; scan–rescan repeatability, ICA pipeline repeatability, and reproducibility between two vendors were assessed.

ICA successfully extracted a consistent oxygen‐enhancement component for all participants. Lung tissue and oxygenated blood displayed the opposite oxygen‐induced signal enhancements. A significant difference in PSE was observed between the lungs of current smokers and nonsmokers. The scan–rescan repeatability and the ICA pipeline repeatability were good.

The developed pipeline demonstrated sensitivity to the signal enhancements of the lung tissue and oxygenated blood at 3 T. The difference in lung PSE between current smokers and nonsmokers indicates a likely sensitivity to lung function alterations that may be seen in mild pathology, supporting future use of our methods in patient studies.