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Gas inhale mr contrast11/6/2022 ![]() ![]() On the other hand, the field of study of pulmonary airflow has recently benefited from advancements in imaging and computation methodology. However, very little data have been published on the influence of CO f on airflow pattern and gas distribution within the lung. CO f can be detected in most subjects during the whole breathing cycle and in all regions of the lung ( 11). In the present study, only cardiogenic flow oscillations (CO f), present in the conducting airways, are considered. Therefore, the cardiac action has an uncontested influence on lung function, but it is unclear how the different observations of cardiogenic oscillations are related to each other. The cardiac cycle is thought to be an important component of gas mixing within the lung ( 12, 13, 15) and leads to oscillations in the concentration of oxygen and carbon dioxide in expired gas ( 5, 6). Cardiogenic oscillations have been intensively observed and recorded in the past in the context of pulmonary physiology measurements made at the mouth with pressure transducers, pneumotachographs ( 1, 20, 29), or gas analyzers ( 6, 15) but also directly inside of the intrathoracic airways during bronchoscopy ( 30). In the literature, the term cardiogenic oscillation has been used to refer to the modulation of the pulmonary gas pressure, flow, or concentration produced by the cardiac cycle. In conclusion, cardiogenic flow oscillations have a significant effect on regional gas flow and distribution within the lungs. Additional 1H structural MR images of the lung volume and synchronized ECG recording revealed that maximum inspiratory flow rates in the LLL of the lungs occurred during systole when the corresponding left lung volume increased, whereas the opposite effect was observed during diastole, with gas flow redirected to the other parts of the lung. In four of the subjects, backflows were observed for a short period of time of the cardiac cycle, demonstrating a pendelluft effect at the carina bifurcation between the left and right lungs. The airflow in the main bronchi showed periodic oscillations at the frequency of the cardiac cycle. The ventilation MR signal and gas inflow in the left lower lobe (LLL) of the lungs were found to oscillate clearly at the cardiac frequency in all subjects, whereas the MR signals in the other parts of the lungs had a similar oscillatory behavior but were smaller in magnitude and in anti-phase to the signal in the left lower lung. This effect is investigated further using dynamic and phase-contrast flow MRI with inhaled 3He during slow inhalations (flow rate ∼100 ml/s) to elucidate airflow dynamics in the main lobes in six healthy subjects. Recently, dynamic MRI of hyperpolarized 3He during inhalation revealed an alternation of the image intensity between left and right lungs with a cardiac origin (Sun Y, Butler JP, Ferrigno M, Albert MS, Loring SH. ![]()
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