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Lung parenchyma: magnetic susceptibility in MR imaging
C J Bergin1, G H Glover, J M Pauly
1Department of Radiology, Stanford University School of Medicine, CA 94305-5105.
Radiology
|September 1, 1991
Summary
Magnetic susceptibility effects in lung MR imaging cause signal loss and frequency shifts. Quantifying these magnetic field variations is crucial for developing advanced lung imaging techniques.
Area of Science:
- Medical Imaging
- Biophysics
- Pulmonary Medicine
Background:
- Magnetic susceptibility variations in lung parenchyma create magnetic field inhomogeneities.
- These inhomogeneities impact magnetic resonance (MR) imaging by causing intravoxel phase dispersion (T2') and resonant frequency shifts (delta v).
Purpose of the Study:
- To quantify magnetic susceptibility effects in normal lung parenchyma using MR imaging.
- To measure T2' decay and delta v at 1.5 Tesla in vivo and ex vivo lung specimens.
Main Methods:
- Quantitative MR imaging at 1.5 T.
- Measurement of T2' decay and delta v in normal lung parenchyma.
- Inclusion of excised inflated human lung and in vivo lungs from adult volunteers.
Main Results:
- Average T2' was 7 msec in excised lung and 6.3 msec in vivo.
- A gravitational gradient in T2' was observed from nondependent to dependent lung regions.
- T2' values increased significantly in atelectatic lung (35 msec) and tumor ( > 140 msec).
- Macroscopic resonant lung frequency increased by 3.6 ppm compared to mediastinal muscle.
Conclusions:
- Magnetic susceptibility effects significantly influence lung MR imaging.
- Quantified T2' and delta v values provide essential data for optimizing MR pulse sequences for lung imaging.
- Understanding these effects is key to improving diagnostic accuracy in pulmonary MR.