ABSTRACT
I. Introduction 413
II. Diagnosis of Asthma 414
III. Treatment of Asthma 415
IV. Radiologic Examination in Asthma 417
V. Hyperpolarized Noble Gas MR Imaging 417
VI. Hyperpolarized Helium-3 MR of Untreated Asthma 419
VII. Hyperpolarized Helium-3 MR Following
Provocation of Asthma 420
A. Exercise Challenge Testing 422
B. Methacholine Challenge Testing 423
VIII. Hyperpolarized Helium-3 MR Following
Treatment of Asthma 424
IX. Summary 425
Acknowledgments 426
References 426
I. Introduction
Asthma is a chronic inflammatory disorder characterized by airway inflam-
mation, recurrent episodes of wheezing, breathlessness, chest tightness, and
cough. The symptoms are usually associated with widespread but variable
airflow obstruction, caused by changes such as bronchoconstriction, edema,
mucus plug formation, and airway remodeling (defined as a process of sustained
disruption and modification of structural cells and tissues leading to the develop-
ment of new airway wall morphology). There is an increase in airway hyper-
responsiveness to a variety of stimuli such as allergens, irritants, cold air, and
viruses (1).
