Hyperpolarized ³He MR lung ventilation imaging in asthmatics: Preliminary findings

Abstract

Asthma is a disease characterized by chronic inflammation and reversible obstruction of the small airways resulting in impaired pulmonary ventilation. Hyperpolarized 3 He magnetic resonance (MR) lung imaging is a new technology that provides a detailed image of lung ventilation. Hyperpolarized 3 He lung imaging was performed in 10 asthmatics and 10 healthy subjects. Seven asthmatics had ventilation defects distributed throughout the lungs compared with none of the normal subjects. These ventilation defects were more numerous and larger in the two symptomatic asthmatics who had abnormal spirometry. Ventilation defects studied over time demonstrated no change in appearance over 30 -60 minutes. One asthmatic subject was studied twice in a three-week period and had ventilation defects which resolved and appeared in that time. This same subject was studied before and after bronchodilator therapy, and all ventilation defects resolved after therapy. Hyperpolarized 3 He lung imaging can detect the small, reversible ventilation defects that characterize asthma. The ability to visualize lung ventilation offers a direct method of assessing asthmatics and their response to therapy. J. Magn. Reson. Imaging 2001;13: 378 -384.

Functional lung imaging using hyperpolarized gas MRI

“…Similar measures, combined with quantitative measures of airway lumen size and wall thickness, may also allow measurement of gas trapping and airway narrowing associated with other obstructive lung diseases such as asthma (24). Although HR CT can provide quantitative assessment and diagnosis of the anatomical features of lung diseases, HP MRI has the means to perform a range of functional measures including regional ventilation (25)(26)(27), and V A /Q mapping (28,29), while also providing images of regional microstructure-in some applications at length scales similar to or smaller than those depicted on CT (30,31)-and all of these measures are performed without ionizing radiation.…”

“…In particular, ventilation imaging using HP MRI in the study of asthma has shown the ability to detect regional patterns of airway closure in moderate to severe disease (Fig. 2) (26) before and after inhalation of albuterol (67) and in mild asthma after inhaled corticosteroid withdrawal (68). Similar studies directly comparing quantitative CT measures to HP He-3 MRI ventilation in COPD and smokers (69), and bronchiolitis obliterans (BO) in lung transplant (70,71) suggest similar sensitivity and regional specificity for detection of obstructive lung disease using the two imaging techniques.…”

“…Early diagnosis and therapy may be critical to help mitigate the severity of the disease in adulthood (4). Several important studies looking at the pattern of ventilation anomalies in asthma have been presented and show strong correlations between FEV 1 and number of ventilation defects (26,99). In one study of 40 subjects, including 20 subjects with moderate to severe asthma, the mean number of ventilation defects per slice was shown to correlate well with FEV 1 (r ϭ -0.735; P Ͻ 0.0001).…”

Combined MR proton lung perfusion/angiography and helium ventilation: Potential for detecting pulmonary emboli and ventilation defects

“…Recently, assessment of regional lung ventilation using hyperpolarized noble gas has emerged as an imaging technique for evaluating patients with lung disease, such as tumor, emphysema, bronchiectasis, cystic fibrosis, and asthma (17)(18)(19)(20)(21)(22)(23)(24). Compared to O 2 -enhanced lung MRI (25,26), which has the advantage of needing no special equipment, 3 He MRI provides high SNR and contrast-to-noise ratio (CNR), with image intensity directly proportional to the local concentration of inhaled 3 He.…”

Feasibility of combining MR perfusion, angiography, and 3He ventilation imaging for evaluation of lung function in a porcine model1

“…The latter technique has shown a high signal-to-noise ratio (SNR), and permits the visualization of pulmonary arteries beyond the subsegmental branches. On the other hand, assessment of regional lung ventilation with hyperpolarized noble gas has emerged as an imaging technique for evaluating lung diseases, including tumors, emphysema, bronchiectasis, cystic fibrosis, and asthma (16)(17)(18)(19)(20)(21)(22)(23). A promising MR technique for visualizing the air spaces of the lung is the use of 3 He gas as a contrast agent.…”