Lung Air Spaces: MR Imaging Evaluation with Hyperpolarized 3He Gas
Eduard E. de Lange, MD1,
John P. Mugler, III, PhD1,
James R. Brookeman, PhD1,
Jack Knight-Scott, PhD1,
Jonathon D. Truwit, MD2,
C. David Teates, MD1,
Thomas M. Daniel, MD3,
Paul L. Bogorad, PhD4 and
Gordon D. Cates, PhD5
1 Departments of Radiology (E.E.d.L., J.P.M., J.R.B., J.K.S., C.D.T.)
2 Internal Medicine (J.D.T.)
3 Surgery (T.M.D.), University of Virginia Health Sciences Center, Box 170, 1000 Lee St, Charlottesville, VA 22908
4 Magnetic Imaging Technologies, Durham, NC (P.L.B.)
5 Department of Physics, Princeton University, Princeton, NJ (G.D.C.).
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Figure 1. Schematic depicts optical pumping and spin exchange. The glass cell is filled with 3He gas and a small quantity of rubidium. Heating of the cell produces rubidium vapor. When the mixture is illuminated by laser light, absorption of the light causes high electronic polarization in the rubidium atoms by means of the process called "optical pumping." When the polarized rubidium atoms collide with the 3He atoms, the polarization is transferred to the 3He nuclei. Transfer of the polarization is referred to as "spin exchange."
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Figure 2. Photograph of the prototypic, close-fitting, 48-MHz radio-frequency coil (arrow) used for acquisition of the hyperpolarized 3He images. The coil is a Helmholtz pair with an element diameter of 28.5 cm, covering the extent of the lungs in most subjects. One coil element is above the subject and the other beneath. Separation between the elements is adjusted for the chest size of the subject.
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Figure 3a. (a) Coronal, (b) axial, and (c) sagittal 3He MR images (two-dimensional FLASH) of the lungs of a healthy subject. Each image was obtained in a single breath hold after inhalation of 1 L of 3He gas. There is uniform distribution of the gas, which displays high signal intensity. The low-intensity structures are the normal blood vessels. The major fissure (arrows) of the lung is seen in a and c. The images were obtained with a 28.5-cm Helmholtz coil. The high signal intensity of the anterior and posterior aspects of the lung shown in b and c, respectively, is caused by the proximity of the coil elements to the chest wall.
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Figure 3b. (a) Coronal, (b) axial, and (c) sagittal 3He MR images (two-dimensional FLASH) of the lungs of a healthy subject. Each image was obtained in a single breath hold after inhalation of 1 L of 3He gas. There is uniform distribution of the gas, which displays high signal intensity. The low-intensity structures are the normal blood vessels. The major fissure (arrows) of the lung is seen in a and c. The images were obtained with a 28.5-cm Helmholtz coil. The high signal intensity of the anterior and posterior aspects of the lung shown in b and c, respectively, is caused by the proximity of the coil elements to the chest wall.
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Figure 3c. (a) Coronal, (b) axial, and (c) sagittal 3He MR images (two-dimensional FLASH) of the lungs of a healthy subject. Each image was obtained in a single breath hold after inhalation of 1 L of 3He gas. There is uniform distribution of the gas, which displays high signal intensity. The low-intensity structures are the normal blood vessels. The major fissure (arrows) of the lung is seen in a and c. The images were obtained with a 28.5-cm Helmholtz coil. The high signal intensity of the anterior and posterior aspects of the lung shown in b and c, respectively, is caused by the proximity of the coil elements to the chest wall.
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Figure 4a. (a) Coronal and (b) axial lung 3He MR images (two-dimensional FLASH) in a middle-aged heavy smoker. There are multiple small ventilation defects (several indicated with arrows) in both lungs. Note that the outer (lateral) edge of the right lung is only faintly visible in a due to incomplete coverage of the chest by the 28.5-cm Helmholtz coil. The coil was repositioned before b was acquired.
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Figure 4b. (a) Coronal and (b) axial lung 3He MR images (two-dimensional FLASH) in a middle-aged heavy smoker. There are multiple small ventilation defects (several indicated with arrows) in both lungs. Note that the outer (lateral) edge of the right lung is only faintly visible in a due to incomplete coverage of the chest by the 28.5-cm Helmholtz coil. The coil was repositioned before b was acquired.
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Figure 5a. (a) Coronal MR image (two-dimensional FLASH) in a 71-year-old patient with severe emphysema was obtained immediately after inhalation of 1 L of hyperpolarized 3He gas. A very large ventilation defect is seen in the lower aspect of the left lung (large straight arrow), and faint signal intensity (open arrow) from the gas is seen at the lung base adjacent to the hemidiaphragm. A large defect is also present at the right base (curved arrow) and a small defect more medially (small straight arrow). (b) Ventilation (wash-in) 133Xe scintigraphic image shows similar bilateral defects (curved and straight arrows) and faint uptake of 133Xe activity (open arrow) adjacent to the left diaphragm. The small defect in the medial aspect of the lower right lung (small straight arrow in a) is difficult to appreciate probably due to the planar whole-lung image, in which the surrounding nuclear activity obscures the small focal defect.
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Figure 5b. (a) Coronal MR image (two-dimensional FLASH) in a 71-year-old patient with severe emphysema was obtained immediately after inhalation of 1 L of hyperpolarized 3He gas. A very large ventilation defect is seen in the lower aspect of the left lung (large straight arrow), and faint signal intensity (open arrow) from the gas is seen at the lung base adjacent to the hemidiaphragm. A large defect is also present at the right base (curved arrow) and a small defect more medially (small straight arrow). (b) Ventilation (wash-in) 133Xe scintigraphic image shows similar bilateral defects (curved and straight arrows) and faint uptake of 133Xe activity (open arrow) adjacent to the left diaphragm. The small defect in the medial aspect of the lower right lung (small straight arrow in a) is difficult to appreciate probably due to the planar whole-lung image, in which the surrounding nuclear activity obscures the small focal defect.
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Figure 6a. (a) Coronal lung 3He image (two-dimensional FLASH) in a 22-year-old healthy subject with mild seasonal allergies and a history of asthma. A very small defect (arrow) but otherwise normal distribution of the gas are seen. (b) Follow-up image obtained 1 week later at the same anatomic level demonstrates a new, large defect (arrow) on the right. The small defect on the left has disappeared. (c) Repeat follow-up image obtained 1 week after b shows that the lungs are normal again.
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Figure 6b. (a) Coronal lung 3He image (two-dimensional FLASH) in a 22-year-old healthy subject with mild seasonal allergies and a history of asthma. A very small defect (arrow) but otherwise normal distribution of the gas are seen. (b) Follow-up image obtained 1 week later at the same anatomic level demonstrates a new, large defect (arrow) on the right. The small defect on the left has disappeared. (c) Repeat follow-up image obtained 1 week after b shows that the lungs are normal again.
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Figure 6c. (a) Coronal lung 3He image (two-dimensional FLASH) in a 22-year-old healthy subject with mild seasonal allergies and a history of asthma. A very small defect (arrow) but otherwise normal distribution of the gas are seen. (b) Follow-up image obtained 1 week later at the same anatomic level demonstrates a new, large defect (arrow) on the right. The small defect on the left has disappeared. (c) Repeat follow-up image obtained 1 week after b shows that the lungs are normal again.
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Figure 7a. Coronal (a) two-dimensional FLASH image (one of 15 sections obtained in a 20-second breath hold [1.3 seconds per section]) and (b) interleaved echo-planar image (one of 15 sections obtained in a 5.7-second breath hold [0.4 seconds per section]) were obtained at approximately the same anatomic level in a healthy subject. Note that the hyperpolarized 3He gas displays similar high signal intensity and there are no substantial differences in diagnostic quality.
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Figure 7b. Coronal (a) two-dimensional FLASH image (one of 15 sections obtained in a 20-second breath hold [1.3 seconds per section]) and (b) interleaved echo-planar image (one of 15 sections obtained in a 5.7-second breath hold [0.4 seconds per section]) were obtained at approximately the same anatomic level in a healthy subject. Note that the hyperpolarized 3He gas displays similar high signal intensity and there are no substantial differences in diagnostic quality.
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Copyright © 1999 by the Radiological Society of North America.
