Second-order Texture Measurements of (3)He Ventilation MRI: Proof-of-concept Evaluation of Asthma Bronchodilator Response

Nanxi Zha; Damien Pike; Sarah Svenningsen; Dante P I Capaldi; David G McCormack; Grace Parraga

doi:10.1016/j.acra.2015.10.010

Second-order Texture Measurements of (3)He Ventilation MRI: Proof-of-concept Evaluation of Asthma Bronchodilator Response

Acad Radiol. 2016 Feb;23(2):176-85. doi: 10.1016/j.acra.2015.10.010. Epub 2015 Nov 18.

Authors

Nanxi Zha¹, Damien Pike², Sarah Svenningsen², Dante P I Capaldi², David G McCormack³, Grace Parraga⁴

Affiliations

¹ Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada.
² Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, London, Canada.
³ Division of Respirology, Department of Medicine, The University of Western Ontario, London, Canada.
⁴ Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, London, Canada. Electronic address: gparraga@robarts.ca.

PMID: 26601971
DOI: 10.1016/j.acra.2015.10.010

Abstract

Rationale and objectives: (3)He magnetic resonance imaging (MRI) can be used to quantify functional responses to asthma therapy and provocation. Ventilation imaging offers quantitative information beyond ventilation defects that have not yet been exploited. Therefore, our objective was to evaluate hyperpolarized (3)He MRI ventilation defect percent (VDP) and compare this and pulmonary function measurements to ventilation image texture features and their changes post-bronchodilator administration in patients with asthma.

Materials and methods: Volunteers with a diagnosis of asthma provided written informed consent to an ethics board-approved protocol and underwent pulmonary function tests and MRI before and after salbutamol inhalation. MR images were analyzed using VDP, and their texture was evaluated via gray-level run-length matrices. These texture classifiers were compared to VDP in responders to bronchodilation based on VDP (VDP responders) and forced expiratory volume in 1 s (FEV1) (FEV1 responders).

Results: In total, 47 patients with asthma (18 males 39 ± 13 years, FEV1 = 79 ± 21%) reported significantly improved FEV1, FEV1/forced vital capacity (FVC), residual volume (RV)/total lung capacity (TLC) (all P = .0001) and VDP (P = .01) post-salbutamol. Post-salbutamol, VDP responders and nonresponders to salbutamol were significantly different for coarse-texture features including long-run emphasis (LRE) and long-run, low gray-level emphasis (LRLGE, both P < .05) and for FEV1 responders to salbutamol, there was significantly different long-run, high gray-level emphasis (LRHGE, P = .04). There were significant relationships for VDP with LRE (R = .50, P = .0003), LRLGE (R = .34, P = .02), and LRHGE (R = .56, P = .0001). Receiver operating characteristic curves showed VDP with the strongest performance (AUC = .92), followed by coarse-texture classifier LRHGE (AUC = .83), FEV1 (AUC = .80), LRE (AUC = .66), FVC (AUC = .58), and LRLGE (AUC = .42).

Conclusions: In patients with asthma, differences in ventilation patchiness post-salbutamol can be quantified using coarse-texture classifiers that are significantly different in bronchodilator responders.

Keywords: (3)He MRI; Texture analysis; asthma; bronchodilator response.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Administration, Inhalation
Adult
Albuterol / administration & dosage*
Area Under Curve
Asthma / diagnostic imaging*
Asthma / physiopathology
Bronchial Provocation Tests / methods
Bronchodilator Agents / administration & dosage*
Female
Forced Expiratory Volume / drug effects
Helium
Humans
Image Enhancement / methods
Isotopes
Lung / diagnostic imaging
Lung / drug effects
Magnetic Resonance Imaging / methods*
Male
Maximal Midexpiratory Flow Rate / drug effects
Middle Aged
ROC Curve
Residual Volume / drug effects
Respiration / drug effects
Respiratory Function Tests / methods
Signal-To-Noise Ratio
Spirometry / methods
Total Lung Capacity / drug effects
Vital Capacity / drug effects

Substances

Bronchodilator Agents
Isotopes
Helium
Albuterol

Grants and funding

MOP 106437/Canadian Institutes of Health Research/Canada