Nuclear Medicine Enables Earlier COPD Diagnosis

In vivo ventilation/perfusion (V/Q) imaging can detect early lung alterations caused by cigarette smoke exposure and provides a noninvasive tool for evaluating lung dysfunction in preclinical studies. This new tool has the potential to be employed clinically to assess and identify the early stages of chronic obstructive pulmonary disease (COPD).

COPD is a slow-progressing, debilitating lung disease that is typically caused by cigarette smoking. Significant characteristics of COPD include chronic inflammation, increased mucus production, small-airway fibrosis, and airspace enlargement. Many individuals with COPD, however, go undetected until their disease has reached a more symptomatic stage and irreversible damage has transpired.

“Better diagnostic tools are needed to detect early changes in smokers to prevent further lung dysfunction and provide patients with individualized treatment regimens,” said N. Renee Labiris, PhD, department of medicine, division of respirology, McMaster University (Hamilton, Ontario, Canada), and one of the authors of the study. “Our preclinical study suggests that not only can V/Q imaging detect early and small changes in lung pathology, the type of V/Q mismatching could provide insight into the underlying pathologies, which current measures of lung function are unable to do.”

In the study, published in the April issue of the Journal of Nuclear Medicine, groups of mice were exposed to cigarette smoke for 50 minutes twice daily, five days a week, for either 8 or 24 weeks. Age-matched control groups of mice were also included in the study for comparison. After the final cigarette smoke exposure, V/Q single photon emission computed tomography (SPECT) was performed, followed by a computed tomography (CT) imaging scan. Histologic lung sections were then gathered and a semiautomated quantitative analysis of airspace enlargement was utilized on whole histology slices.

Functional impairment in the study was observed in the lungs caused by increased inflammation and airspace enlargement. This functional impairment, measured with SPECT V/Q imaging, identified COPD characteristics before CT was able to identify structural alterations in the lungs. Furthermore, V/Q mismatching progressively increased during cigarette smoke exposure in mice compared to age-matched control mice and offered insight into the underlying pathology causing COPD.

“V/Q imaging is a common nuclear medicine technique, and SPECT/CT systems are increasingly used in clinical practice,” noted Dr. Labiris. “As such, the technology examined in this study can be carried out in both preclinical and clinical settings, enabling researchers to translate preclinical investigations of disease, associated functional abnormalities and future drug targets into an improved understanding and management of the disease in patients.”

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