HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tooker, A. C. Articles by Albert, M. S. Search for Related Content PubMed PubMed Citation Articles by Tooker, A. C. Articles by Albert, M. S.

Distal Airways in Humans: Dynamic Hyperpolarized ³He MR Imaging—Feasibility¹

¹ From the Department of Radiology, Brigham and Women’s Hospital, 221 Longwood Ave, Boston, MA 02115. Received January 10, 2002; revision requested March 4; final revision received August 8; accepted August 21. Address correspondence to M.S.A. (e-mail: malbert@bwh.harvard.edu).

View larger version (132K): [in a new window]   Figure 1a. Comparison of (a-c) dynamic and (d) static images of the human lung. Dynamic (a) coronal, (b) transverse, and (c) sagittal projection images obtained during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition). (d) Static coronal multisection image obtained during breath hold after inhalation of 1 L of hyperpolarized 3He gas by using GRE pulse sequence (2.8/70, 18° flip angle, 256 x 128 matrix, 39-cm FOV, 0.75 phase FOV, 13-mm section thickness, and 31.25-kHz bandwidth). On dynamic images, the airways are clearly visible; on the static image, the airways are obscured by the lung periphery.

View larger version (116K): [in a new window]   Figure 1b. Comparison of (a-c) dynamic and (d) static images of the human lung. Dynamic (a) coronal, (b) transverse, and (c) sagittal projection images obtained during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition). (d) Static coronal multisection image obtained during breath hold after inhalation of 1 L of hyperpolarized 3He gas by using GRE pulse sequence (2.8/70, 18° flip angle, 256 x 128 matrix, 39-cm FOV, 0.75 phase FOV, 13-mm section thickness, and 31.25-kHz bandwidth). On dynamic images, the airways are clearly visible; on the static image, the airways are obscured by the lung periphery.

View larger version (113K): [in a new window]   Figure 1c. Comparison of (a-c) dynamic and (d) static images of the human lung. Dynamic (a) coronal, (b) transverse, and (c) sagittal projection images obtained during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition). (d) Static coronal multisection image obtained during breath hold after inhalation of 1 L of hyperpolarized 3He gas by using GRE pulse sequence (2.8/70, 18° flip angle, 256 x 128 matrix, 39-cm FOV, 0.75 phase FOV, 13-mm section thickness, and 31.25-kHz bandwidth). On dynamic images, the airways are clearly visible; on the static image, the airways are obscured by the lung periphery.

View larger version (133K): [in a new window]   Figure 1d. Comparison of (a-c) dynamic and (d) static images of the human lung. Dynamic (a) coronal, (b) transverse, and (c) sagittal projection images obtained during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition). (d) Static coronal multisection image obtained during breath hold after inhalation of 1 L of hyperpolarized 3He gas by using GRE pulse sequence (2.8/70, 18° flip angle, 256 x 128 matrix, 39-cm FOV, 0.75 phase FOV, 13-mm section thickness, and 31.25-kHz bandwidth). On dynamic images, the airways are clearly visible; on the static image, the airways are obscured by the lung periphery.

View larger version (35K): [in a new window]   Figure 2. Graph shows the SNRs of the trachea, first- through fourth-generation airways, and the lung periphery for dynamic coronal projection images of the lung obtained by using the fast GRE pulse sequence with a 9° flip angle. The SNR in the central airways increases during inhalation. The SNR in the airways reaches a steady-state value, at which point the SNR in the airways is five to 20 times greater than the SNR in the lung periphery.

View larger version (150K): [in a new window]   Figure 3a. Time series of dynamic coronal projection images of the lung acquired during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence with a flip angle of 16°. As the inhalation continued, the SNR in the airways increased while the SNR in the lung periphery remained constant. On images obtained during (a, b) early inhalation, the distal airways are not as clearly distinguishable from the lung periphery as on images obtained during (c, d) late inhalation.

View larger version (130K): [in a new window]   Figure 3b. Time series of dynamic coronal projection images of the lung acquired during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence with a flip angle of 16°. As the inhalation continued, the SNR in the airways increased while the SNR in the lung periphery remained constant. On images obtained during (a, b) early inhalation, the distal airways are not as clearly distinguishable from the lung periphery as on images obtained during (c, d) late inhalation.

View larger version (126K): [in a new window]   Figure 3c. Time series of dynamic coronal projection images of the lung acquired during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence with a flip angle of 16°. As the inhalation continued, the SNR in the airways increased while the SNR in the lung periphery remained constant. On images obtained during (a, b) early inhalation, the distal airways are not as clearly distinguishable from the lung periphery as on images obtained during (c, d) late inhalation.

View larger version (120K): [in a new window]   Figure 3d. Time series of dynamic coronal projection images of the lung acquired during inhalation of 500 mL of hyperpolarized 3He mixed with 500 mL of 4He by using the fast GRE pulse sequence with a flip angle of 16°. As the inhalation continued, the SNR in the airways increased while the SNR in the lung periphery remained constant. On images obtained during (a, b) early inhalation, the distal airways are not as clearly distinguishable from the lung periphery as on images obtained during (c, d) late inhalation.

View larger version (148K): [in a new window]   Figure 4a. (a-c) Dynamic coronal projection images of the lung acquired by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition) and (a) 9°, (b) 16°, and (c) 21° flip angles. The number of airway generations distinguishable from the lung periphery increased as the flip angle increased from 9° to 16°. As the flip angle continued to increase beyond 16°, the number of visible airway generations decreased.

View larger version (135K): [in a new window]   Figure 4b. (a-c) Dynamic coronal projection images of the lung acquired by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition) and (a) 9°, (b) 16°, and (c) 21° flip angles. The number of airway generations distinguishable from the lung periphery increased as the flip angle increased from 9° to 16°. As the flip angle continued to increase beyond 16°, the number of visible airway generations decreased.

View larger version (90K): [in a new window]   Figure 4c. (a-c) Dynamic coronal projection images of the lung acquired by using the fast GRE pulse sequence (1.2/4.4, 160 x 128 matrix, 46-cm FOV, 0.75 phase FOV, 62.5-kHz bandwidth, and 50-msec delay after acquisition) and (a) 9°, (b) 16°, and (c) 21° flip angles. The number of airway generations distinguishable from the lung periphery increased as the flip angle increased from 9° to 16°. As the flip angle continued to increase beyond 16°, the number of visible airway generations decreased.