Imaging of lung function using hyperpolarized helium-3 magnetic resonance imaging: Review of current and emerging translational methods and applications

Abstract

During the past several years there has been extensive development and application of hyperpolarized helium-3 (HP (3)He) magnetic resonance imaging (MRI) in clinical respiratory indications such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, radiation-induced lung injury, and transplantation. This review focuses on the state-of-the-art of HP (3)He MRI and its application to clinical pulmonary research. This is not an overview of the physics of the method, as this topic has been covered previously. We focus here on the potential of this imaging method and its challenges in demonstrating new types of information that has the potential to influence clinical research and decision making in pulmonary medicine. Particular attention is given to functional imaging approaches related to ventilation and diffusion-weighted imaging with applications in chronic obstructive pulmonary disease, cystic fibrosis, asthma, and radiation-induced lung injury. The strengths and challenges of the application of (3)He MRI in these indications are discussed along with a comparison to established and emerging imaging techniques.

Copyright © 2010 Wiley-Liss, Inc.

Figures

Figure 1. HP He Magnetic Resonance Imaging Static Ventilation Centre Coronal Slice Images

(a) Healthy volunteer 45y female with FEV1 predicted=118%; (b) Chronic Obstructive Pulmonary Disease 79y male with FEV1 predicted=54%; (c) Asthma subject at baseline without provocation 26yr male with FEV1 predicted=77%; (d) Cystic Fibrosis 23y female with FEV1 predicted=58%.

Figure 2. Comparison of high resolution Computed tomography and HP He Magnetic Resonance Imaging in Chronic Obstructive Pulmonary Disease

Female COPD subject 63y with FEV1 predicted=22%; (a) Centre slice coronal plane reconstruction of high resolution CT; (b) HP He MRI centre coronal slice ventilation image.

Figure 3. Comparison of HP He Apparent Diffusion Coefficient Maps for Healthy Volunteer and Subject with Chronic Obstructive Pulmonary Disease

(a) Healthy Volunteer male age 58y FEV1 predicted=108% (i) ventilation (ii) ADC map (iii) ADC histogram. (b) Chronic Obstructive Pulmonary disease male subject age 52y FEV1 predicted=51% (i) ventilation (ii) ADC map (iii) ADC histogram.

Figure 4

Spin density and ADC map using single inhalation of HP Xe-129 MRI. The ADC values are much lower due to high density of Xe-129, which may be advantageous in certain diseases for short range diffusion measures. Image courtesy Dr. Bastiaan Driehuys and GE Healthcare.

Figure 5

Comparison of short (top row) and long (bottom row) range diffusion in healthy subject (left) and asthma (middle) and COPD patients (right). Image courtesy Dr. Chengbo Wang, University of Virginia.

Figure 6

Coronal maximum intensity projections of a 3D dynamic imaging study using HP 3He-MRI to assess ventilation and gas trapping using a forced exhalation maneuver in asthma. Breath-hold encompasses the time from 10–13s followed by a forced exhalation maneuver showing gas trapping in the left lung most clearly visualized at 25 s (arrow). This patient’s FEV1 was normal, 94% predicted, before and after imaging suggesting significant subclinical heterogeneity and abnormalities of ventilation exist in this patient population.

Figure 7

Results from 3D dynamic MRI in a subclinical finding during inspiration, breath-hold and forced expiration. MRI results in a,b are compared to follow-up MDCT in the same subject in c,d showing hyperlucency in the RUL due to air trapping on MDCT (arrows c,d). Plots of signal time-course for dynamic MRI for the right upper lobe (yellow) compared with left upper lung (green) in the same case. Hyper-intense signal on HP 3He was found to correspond to the 2nd segment that was not blocked by by a pulmonary aneurysm (green). Note delayed filling as evident by the later time-to-peak signal enhancement relative to the expected trapezoidal shaped enhancement curve in the contra-lateral left lung region.