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Published online before print March 27, 2003, 10.1148/radiol.2272012146
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(Radiology 2003;227:575-579.)
© RSNA, 2003

Technical Developments

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

Angela C. Tooker, MEng, Kwan Soo Hong, PhD, Erin L. McKinstry, BS, Philip Costello, MD, Ferenc A. Jolesz, MD and Mitchell S. Albert, PhD

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).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Dynamic hyperpolarized helium 3 (3He) magnetic resonance (MR) imaging of the human airways is achieved by using a fast gradient-echo pulse sequence during inhalation. The resulting dynamic images show differential contrast enhancement of both distal airways and the lung periphery, unlike static hyperpolarized 3He MR images on which only the lung periphery is seen. With this technique, up to seventh-generation airway branching can be visualized.

© RSNA, 2003

Index terms: Bronchi, 60.92 • Helium • Lung, anatomy, 60.92 • Lung, MR, 60.12143 • Magnetic resonance (MR), contrast enhancement, 60.121412, 61.12143 • Magnetic resonance (MR), nuclei other than H, 60.121412, 60.12147


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Since its inception (1), hyperpolarized helium 3 (3He) magnetic resonance (MR) imaging has rapidly advanced as a technique for depicting the human lungs (2–11). Most hyperpolarized 3He MR imaging to date has been static imaging, in which the lungs are filled with hyperpolarized 3He gas before MR imaging begins. Static ventilation images show only the lung periphery (ie, alveolar space). Radio-frequency pulses simultaneously destroy signal in all parts of the lung, and thus, signal from the lung periphery and signal from the airways cannot be differentiated. Images of the lung periphery provide information about the ventilation patterns in the lungs and are useful for making diagnoses, tracking the time course of diseases, and determining the effectiveness of various treatments (4–11). Visualization of the airways, however, may be as important as visualization of the lung periphery. Information about airways and how they function during inspiration and expiration can determine the causes of and suggest possible treatments for various pulmonary diseases (12,13).

Chen et al (14) have obtained dynamic images of the distal airways of guinea pigs. The relatively few dynamic images of the human airways that have been obtained, however, show only the larger central airways (8,14,15). Unfortunately, current dynamic imaging techniques rely on fast pulse sequences (ie, high temporal resolution) that must be specially programmed (8,15). The purpose of our study was to report our approach, which allows visualization of distal airways in humans during one inhalation of hyperpolarized 3He gas, without the need for specialized pulse sequences.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Six adult volunteers (five women, one man; age range, 22–40 years) underwent imaging by using a protocol approved by the institutional review board at our hospital, and informed consent was obtained from all volunteers. All subjects were nonsmokers and reported no history of lung disease.

The 3He nuclei were hyperpolarized by means of collisional spin exchange (16,17) with optically pumped rubidium vapor by using a custom-built polarization device. After 7 hours of optical pumping, 1 L of hyperpolarized 3He gas was produced, with polarization levels of 10%–20%. For each imaging experiment, 500 mL of hyperpolarized 3He gas was mixed with 500 mL of helium 4 (4He) for a total of 1 L. The gas was transferred to a plastic bag (Tedlar; Jensen Inert Products, Coral Springs, Fla), with an attached 30-cm plastic breathing tube, and was transported 30 m to the imager for inhalation by the subject. After two inspirations of room air, the hyperpolarized 3He gas was inhaled over 5–8 seconds. No breath holding was required of the subjects during dynamic imaging experiments.

A 1.5-T MR imaging system (Signa LX, software version 8.4; GE Medical Systems, Milwaukee, Wis) was used for hyperpolarized 3He imaging. To perform hyperpolarized 3He MR imaging, a heterodyne system (18) was added to enable it with broadband capabilities. The radio-frequency coil used was a flexible quadrature wraparound lung coil (Midwest RF, Hartland, Wis), 115 x 34 cm2, tuned to the 3He frequency. Coronal proton images of the lung were first acquired for shimming and localization. Hyperpolarized 3He dynamic coronal projection images of the lung were obtained with the fast gradient-echo (GRE) pulse sequence. Imaging was initiated before the inhalation of hyperpolarized 3He gas and continued for the duration of the inhalation. Fifty dynamic images were acquired, and the time per image was 433 msec. Other imaging parameters were the following: repetition time msec/echo time msec, 1.2/4.4; flip angle, 9°–25°; matrix, 160 x 128; field of view (FOV), 46 cm; phase FOV, 0.75 (by decreasing the FOV in the right and left direction to 34.5 cm [ie, 75% of 46] and the number of pulses or phase-encoding steps per image to 96 [ie, 75% of 128], with no change in spatial resolution); bandwidth, 62.5 kHz; and delay after acquisition, 50 msec.

All images were analyzed (MATLAB, version 6; The Mathworks, Natick, Mass) by multiple authors (A.C.T., K.S.H., E.L.M.), with consensus regarding the resulting data. Regions of interest containing only the desired airway or the lung periphery were selected. The signal-to-noise ratio (SNR) was then calculated as the average signal of the pixels in that region divided by the average noise. The noise was the average signal in a region of interest, 50 x 50 pixels, outside of the body. The average SNRs of different airway generations and of the periphery were calculated for five to 10 images from each experiment. This enabled the SNRs in particular airways and the periphery to be tracked during both inhalation and exhalation. To evaluate how clearly the airways can be distinguished from the periphery with different flip angles, the ratios of the average airway SNR to the average periphery SNR were calculated for each airway generation.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Dynamic projection images of the lung were obtained during inhalation of hyperpolarized 3He gas with the fast GRE pulse sequence. Figure 1a shows a representative coronal image. The coronal imaging plane allows easy quantification of visible airway generations. Transverse (Fig 1b) and sagittal (Fig 1c) images demonstrate the versatility of this technique. The technique enables the airways to be clearly distinguished from the surrounding periphery, regardless of the imaging plane. For purposes of comparison, one representative section of a static coronal multisection ventilation image is also shown (Fig 1d). The static image was obtained during a breath hold after inhalation of 1 L of hyperpolarized 3He gas by using the GRE pulse sequence. Unlike on the dynamic projection images obtained with our technique, the airways are not visible on the static ventilation image because they are obscured by the signal from the lung periphery.



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  		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.

 


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  		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.

 


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  		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.

 


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  		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.

 
SNRs were tracked from the beginning of inhalation to the end of exhalation for several representative airway generations, as well as the lung periphery (Fig 2), for a time series of images obtained with a 9° flip angle. A representative time series of the dynamic coronal projection images of the lung (Fig 3) illustrates the changing SNRs in both the airways and the lung periphery during inhalation and exhalation. The SNR of the trachea, bronchi (first-generation airway), second- through fourth-generation airways, and the lung periphery (identified according to the Weibel model [19] of airway structure) are shown. At the onset of inhalation (image numbers 1–4, Fig 2), the mean SNR of the airways is approximately 30, while the mean SNR of the lung periphery is approximately 10 (ie, they differ by a factor of 3). Thus, the airways at the beginning of inhalation cannot be clearly distinguished from the lung periphery (Fig 3a, 3b). As the inhalation progresses, SNRs in the airways increase (image numbers 4–8, Fig 2); hence, more airways are distinguishable from the lung periphery during the late inhalation phase (Fig 3c, 3d) than during the early inhalation phase (Fig 3a, 3b). Approximately 4 seconds after the start of inhalation, (image number 8, Fig 2), the SNRs of the airways plateau (image numbers 8–11, Fig 2) and remain relatively constant until the inhalation is complete (image number 11, Fig 2), whereupon the SNRs begin to decrease. This plateau marks the beginning of the steady-state period of airway visualization, during which the SNRs of the airways are five to 20 times greater than the mean SNR of the lung periphery, allowing the sole visualization of the airways up to the seventh generation. Once the exhalation has begun (image numbers 11 and 12, Fig 2), the SNRs of both the airways and the periphery decrease. These trends in the airways and periphery SNRs have been observed with all flip angles tested and have been repeated with multiple subjects.



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  		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.

 


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  		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.

 


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  		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.

 


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  		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.

 


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  		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.

 
The ratio of the airway SNRs to the mean lung periphery SNR is a crucial indicator in determining the visibility of the airways. If the ratio is not large enough (ie, below ~3), the airways will not be easily distinguishable from the lung periphery. The Table shows a quantitative analysis of the ratio of airway SNRs to lung periphery SNR for flip angles 9°, 13°, 16°, 21°, and 25°. Several observations can be made from the data in the Table. The trachea SNR is 20 to 50 times greater than the mean SNR of the lung periphery. The SNR decreases as the airway generation increases so that by the fourth generation, the SNR is only five to 15 times greater than the mean SNR of the lung periphery. The central airways, therefore, are more clearly distinguishable than the distal airways with all flip angles. Figure 4 shows representative dynamic coronal projection images of the lung with flip angles of 9° (Fig 4a), 16° (Fig 4b), and 21° (Fig 4c). Figure 4a (small 9° flip angle) reveals some distal airways but still captures mostly lung periphery. Figure 4b (moderate 16° flip angle), however, reveals predominantly airways. As seen in the Table, the SNRs for all generations captured with 13° and 16° flip angles are two to three times greater than those captured with a 9° flip angle. Thus, as the flip angle increases from 9° to 16°, the number of distal airway generations distinguishable from the lung periphery increases. As the flip angle increases further, however, the SNRs from the distal airways begin to decrease. The SNRs for 21° and 25° flip angles in the distal airways (Table) are smaller than the SNRs for 16° flip angles. In Figure 4c, obtained with a large 21° flip angle, fewer airway generations are visible compared with those that are visible in Figure 4b, which was obtained with a moderate 16° flip angle.


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  		Ratio of Airways SNR to Lung Periphery SNR for Trachea and First Through Seventh Generations

 


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  		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.

 


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  		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.

 


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  		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.

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The approach presented in this article allows us to obtain images that show up to the seventh-generation distal airways (ie, depict the endoluminal column of hyperpolarized 3He gas). The airway information gathered with this technique does not require a high temporal resolution. Moreover, we have captured human airway images by using a single inhalation of hyperpolarized 3He gas.

The number of airway generations observed with this technique is dependent on the flip angle, as was noted by Chen et al (14). In general, for greater flip angles, more airway generations are visible and for smaller flip angles, more lung periphery is visible. If the flip angle is increased beyond a critical flip angle, fewer airway generations can be visualized. Because of the nonrenewability of the polarized magnetization of hyperpolarized noble gases, very large flip angles yield little information because they destroy excessive amounts of the polarized magnetization of the gas. Typical hyperpolarized noble gas imaging with GRE techniques is performed with flip angles between 5° and 30°.

The nonrenewability of the polarized magnetization in the hyperpolarized 3He gas establishes a critical flip angle of approximately 16°. The exact value of the critical flip angle is dependent on the airway generation to be visualized. For flip angles greater than the critical flip angle, the polarized magnetization is destroyed before the hyperpolarized 3He gas can reach the distal airways, thereby decreasing the signal in both these airways and in the lung periphery. This can be quantitatively observed in the decreasing SNRs as the flip angle increases for the 16°, 21°, and 25° flip angles (Table), as well as qualitatively in the corresponding images (Fig 4). Below the critical flip angle, we observe only the beneficial destruction of the lung periphery signal; the airway signal is maintained due to the constant inhalation of hyperpolarized 3He gas. For 9°, 13°, and 16° flip angles, the Table shows an increase in the SNR ratios of the airways to the lung periphery as the flip angle increases, which corresponds to an increase in the number of airway generations distinguishable from the lung periphery.

Findings in recent studies with hyperpolarized 3He dynamic human lung imaging have provided useful information about the function of lungs, and the dynamic techniques used enabled depiction of the central airways (8,14,15). Salerno et al (8) obtained dynamic airway images in humans by using a specialized spiral pulse sequence with a high temporal resolution. With this technique, they were able to image the lung periphery and the central airways. Chen et al (14) and Viallon et al (20) obtained airway images of guinea pigs with varying degrees of airway resolution. In their studies, a radial trajectory projection reconstruction sequence, requiring eight inhalations of hyperpolarized 3He gas per image, was used. Their approach has limited applicability for human studies, however, because it requires multiple breaths of hyperpolarized 3He gas and has long image acquisition times. Given current polarization methods, it is impractical to produce the large volumes of hyperpolarized 3He gas necessary for several continuous breaths by humans. By contrast, the techniques presented here produce human airway images with similar resolution (ie, similar numbers of visible airway generations) as those obtained by Chen et al (14) and Viallon et al (20), while only requiring one breath of hyperpolarized 3He gas.

Two general methods are currently used in pulmonary MR imaging with hyperpolarized noble gases: static (6) and dynamic imaging (8,14,15,20–22). Static pulmonary MR imaging involves imaging several sections of the lung during a single breath hold, this gives three-dimensional information about the lung periphery structure. Researchers have obtained static multisection images of the lungs by using a variety of imaging protocols. The ventilation defects observed with static imaging characterize various lung diseases, such as asthma (9), emphysema (5–7), cystic fibrosis (10), and bronchiolitis obliterans (11). However, depiction of airways by using static hyperpolarized 3He methods is limited, because the lung periphery overshadows the signal from the airways. During static imaging, radio-frequency pulsing simultaneously destroys the polarized magnetization in the airways and periphery, and hence, the signal intensity in the lung periphery is comparable with that in the airways.

Dynamic pulmonary hyperpolarized 3He MR imaging consists of imaging the lungs during inspiration. The images are obtained as the gas flows through the airways to the lung periphery. There is limited time during the early inspiration phase, however, in which the gas travels solely through the airways and during which the signal will result only from the polarized magnetization in the airways. After this point, the signal from the lung periphery obscures the signal from the airways. Therefore, it has traditionally been necessary to use a pulse sequence with a high temporal resolution (8,14,15,20–22) to obtain images of the airways as the hyperpolarized 3He gas initially enters the lungs. Such fast imaging sequences are not typically available with most MR imagers and must be specially programmed. Our dynamic technique does not require fast imaging sequences but rather exploits the nonrenewability of the hyperpolarized 3He gas to visualize the distal airways.

Our approach can easily be applied in a clinical setting to image the airways and the lung periphery. Clearly a new direction for MR imaging research, the imaging approach presented in this article provides information currently not available with other techniques. Moreover, this technique provides the ability to quantify airway images (ie, airway diameters and volumes) that can prove invaluable in building models of airway structure and function. In the future, dynamic hyperpolarized 3He imaging of the airways may play a role in the investigation of the distinctive nature of pulmonary airway narrowing and expansion in asthmatic lungs. Hyperpolarized 3He dynamic airway imaging might provide a quantitative assessment of the degree of airway closure and the subsequent number of nonventilated alveolar regions.


   FOOTNOTES
 
Abbreviations: FOV = field of view, GRE = gradient echo, SNR = signal-to-noise ratio

Author contributions: Guarantors of integrity of entire study, P.C., F.A.J., M.S.A.; study concepts and design, A.C.T., K.S.H., M.S.A.; literature research, A.C.T., E.L.M.; experimental studies, A.C.T., K.S.H., E.L.M.; data acquisition and analysis/interpretation, A.C.T., K.S.H., E.L.M., M.S.A.; manuscript preparation, A.C.T., E.L.M., M.S.A.; manuscript definition of intellectual content, A.C.T., M.S.A.; manuscript editing, A.C.T., E.L.M., K.S.H., M.S.A.; manuscript revision/review and final version approval, all authors.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Albert MS, Cates GD, Driehuys B, et al. Biological magnetic resonance imaging using laser-polarized 129Xe. Nature 1994; 370:199-201.[CrossRef][Medline]
  2. Black RD, Middleton HL, Cates GD, et al. In vivo He-3 MR images of guinea pig lungs. Radiology 1996; 199:867-870.[Abstract/Free Full Text]
  3. Macfall JR, Charles HC, Black RD, et al. Human lung air spaces: potential for MR imaging with hyperpolarized He-3. Radiology 1996; 200:553-558.[Abstract/Free Full Text]
  4. Kauczor HU, Hofmann D. Kreitner KF, et al. Normal and abnormal pulmonary ventilation: visualization at hyperpolarized He-3 MR imaging. Radiology 1996; 201:564-568.[Abstract/Free Full Text]
  5. Kauczor HU, Ebert M, Kreitner KF, et al. Imaging of the lungs using 3He MRI: preliminary clinical experience in 18 patients with and without lung disease. J Magn Reson Imaging 1997; 7:538-543.[Medline]
  6. De Lange EE, Mugler JP, III, Brookeman JR, et al. Lung air spaces: MR imaging evaluation with hyperpolarized 3He gas. Radiology 1999; 210:851-857.[Abstract/Free Full Text]
  7. Saam BT, Yablonskiy DA, Kodibagkar VD, et al. MR imaging of diffusion of 3He gas in healthy and diseased lungs. Magn Reson Med 2000; 44:174-179.[CrossRef][Medline]
  8. Salerno M, Altes TA, Brookeman JR, de Lange EE, Mugler JP, III. Dynamic spiral MRI of pulmonary gas flow using hyperpolarized 3He: preliminary studies in healthy and diseased lungs. Magn Reson Med 2001; 46:667-677.[CrossRef][Medline]
  9. Altes TA, Powers PL, Knight-Scott J, et al. Hyperpolarized 3He MR lung ventilation imaging in asthmatics: preliminary findings. J Magn Reson Imaging 2001; 13:378-384.[CrossRef][Medline]
  10. Donnelly LF, Macfall JR, McAdams HP, et al. Cystic fibrosis: combined hyperpolarized 3He-enhanced and conventional proton MR imaging in the lung–preliminary observations. Radiology 1999; 212:885-889.[Abstract/Free Full Text]
  11. McAdams H, Palmer S, Donnelly L, et al. Hyperpolarized 3He-enhanced MR imaging of lung transplant recipients: preliminary results. AJR Am J Roentgenol 1999; 173:955-959.[Abstract/Free Full Text]
  12. Gillis HL, Lutchen KR. Airway remodeling in asthma amplifies heterogeneous smooth muscle shortening causing hyperresponsiveness. J Appl Physiol 1998; 86:2001-2012.
  13. Lutchen KR, Hantos A, Petak F, Adamicza A, Suki B. Airway inhomogeneities contribute to apparent lung tissue mechanics during constriction. J Appl Physiol 1996; 80:1841-1849.[Abstract/Free Full Text]
  14. Chen XJ, Chawla MS, Hedlund LW, Möller HE, MacFall JR, Johnson GA. MR microscopy of lung airways with hyperpolarized 3He. Magn Reson Med 1998; 39:79-84.[Medline]
  15. Schreiber WC, Weiler N, Kauczor HU, et al. Ultraschnelle MRT der lungenventilation mittels hochpolarisiertem helium-3. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2000; 172:129-133.[Medline]
  16. Happer W, Miron E, Schaefer S, Schreiber D, van Wijngaarden WA, Zeng X. Polarization of the nuclear spins of noble-gas atoms by spin exchange with optically pumped alkali-metal atoms. Phys Rev A 1984; 29:3092-3110.[CrossRef]
  17. Leawoods JC, Yablonskiy DA, Saam B, Gierada DS, Conradi MS. Hyperpolarized 3He gas production and MR imaging of the lung. Concepts Magn Reson 2001; 13:277-293.[CrossRef]
  18. Tooker A, Zhang A, Venkatesh A, Hong KS, Albert M. Hardware for performing hyperpolarized helium imaging on a clinical MR imager (abstr) In: Proceedings of the Ninth Meeting of the International Society for Magnetic Resonance in Medicine. Berkeley, Calif: International Society for Magnetic Resonance in Medicine, 2001; 1154.
  19. Weibel ER. Morphometry of the human lung Berlin, Germany: Springer, 1963.
  20. Viallon M, Cofer GP, Suddarth SA, et al. Functional MR microscopy of the lung using hyperpolarized 3He. Magn Reson Med 1999; 41:787-792.[CrossRef][Medline]
  21. Moller HE, Chen XJ, Chawla MS, Driehuys B, Hedlund LW, Johnson GA. Signal dynamics in magnetic resonance imaging of the lung with hyperpolarized noble gases. J Magn Reson 1998; 135:133-143.[CrossRef][Medline]
  22. Moller HE, Chen XJ, Chawla MS, et al. Sensitivity and resolution in 3D NMR microscopy of the lung with hyperpolarized noble gases. Magn Reson Med 1999; 41:800-808.[CrossRef][Medline]



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M. Dolovich and R. Labiris
Imaging Drug Delivery and Drug Responses in the Lung
Proceedings of the ATS, December 1, 2004; 1(4): 329 - 337.
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