Three-dimensional oxygen-enhanced MRI of the human lung at 1.5T with ultra-fast balanced steady-state free precession

Background Emerging quantitative cardiac magnetic resonance imaging (CMRI) techniques use cine balanced steady-state free precession (bSSFP) to measure myocardial signal intensity and probe underlying physiological parameters. This correlation assumes that steady-state is maintained uniformly throughout the heart in space and time. Purpose To determine the effects of longitudinal cardiac motion and initial slice position on signal deviation in cine bSSFP imaging by comparing two-dimensional (2D) and three-dimensional (3D) acquisitions. Material and Methods Nine healthy volunteers completed cardiac MRI on a 1.5-T scanner. Short axis images were taken at six slice locations using both 2D and 3D cine bSSFP. 3D acquisitions spanned two slices above and below selected slice locations. Changes in myocardial signal intensity were measured across the cardiac cycle and compared to longitudinal shortening. Results For 2D cine bSSFP, 46% ± 9% of all frames and 84% ± 13% of end-diastolic frames remained within 10% of initial signal intensity. For 3D cine bSSFP the proportions increased to 87% ± 8% and 97% ± 5%. There was no correlation between longitudinal shortening and peak changes in myocardial signal. The initial slice position significantly impacted peak changes in signal intensity for 2D sequences ( P < 0.001). Conclusion The initial longitudinal slice location significantly impacts the magnitude of deviation from steady-state in 2D cine bSSFP that is only restored at the center of a 3D excitation volume. During diastole, a transient steady-state is established similar to that achieved with 3D cine bSSFP regardless of slice location.

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MRI Study on Tibial Nerve of the Ankle Canal and Its Branches: A method of multiplanar reconstruction with three-dimensional dual-excitation balanced steady-state free precession sequence

10.21203/rs.3.rs-34907/v1 ◽

2020 ◽

Author(s):

Yan Zhang ◽

Xucheng He ◽

Juan Li ◽

Ju Ye ◽

Wenjuan Han ◽

...

Keyword(s):

Steady State ◽

Steady State Free Precession ◽

Tibial Nerve ◽

Three Dimensional ◽

Multiplanar Reconstruction ◽

Medial Malleolus ◽

Free Precession ◽

Medial Plantar Nerve ◽

Lateral Plantar Nerve ◽

Starting Point

Abstract Background: The display of tibial nerve and its branches in the ankle canal is helpful for the diagnosis of local lesions and compression, and also for clinical observation and surgical planning.The aim of this study was to investigate the feasibility of three-dimensional dual-excitation balanced steady-state free precession sequence (3D-FIESTA-C) multiplanar reconstruction (MPR) display of tibial nerve and its branches of the ankle canal.The subjects were 20 healthy volunteers (40 ankles), aged 22-50, with no history of ankle joint desease. 3D-FIESTA-Csequence was used in the 3.0t magnetic resonance equipment for imaging. During the scanning, each foot was at a 90-degree angle to the tibia so that the results of measurement are more accurate .The tibial nerve of the ankle canal and its branches were displayed and measured at the same level through multiplanar reconstruction.Results: Most of the tibial nerve bifurcation points were located in the ankle canal (57.5%), few (42.5%) were located at the proximal end of the ankle canal, and none was found away from the distal end. The bifurcation between the medial plantar nerve and the lateral plantar nerve is on the line between the tip of the medial malleolus and the calcaneus, and it’s angle is between 6° and 35°.The average cross-sectional diameter of the medial plantar nerve is about mm, and the lateral plantar nerve about mm. In MPR images, the display rates of both the medial calcaneal nerve and the subcalcaneal nerve were 100%, and the starting point of the subcalcaneal nerve was always at the distal end of the starting point of the medial calcaneal nerve. In 55% of cases, there were more than 2 medial calcaneal nerve innervations.Conclusion: The 3D-FIESTA-C MPR can display the morphological features and positions of tibial nerve and its branches. By measuring the distance between each bifurcation point, the tip of the medial malleolus and the angle between this line and the horizontal line that passes the tip of the medial malleolus, the bifurcation point’s projection position on the body surface can be accurately marked. This method not only benefited the imaging diagnosis of tibial nerve and branch-related lesions of the ankle canal, but also provided a good imaging basis to plan the clinical operation of the ankle canal and avoid surgical injury.

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