Identifying the heterogeneity of COPD by V/P SPECT: a new tool for improving the diagnosis of parenchymal defects and grading the severity of small airways disease

Abstract

Introduction

Airway obstruction and possible concomitant pulmonary diseases in COPD cannot be identified conventionally with any single diagnostic tool. We aimed to diagnose and grade COPD severity and identify pulmonary comorbidities associated with COPD with ventilation/perfusion single-photon emission computed tomography (V/P SPECT) using Technegas as the functional ventilation imaging agent.

Methods

94 COPD patients (aged 43–86 years, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I–IV) were examined with V/P SPECT and spirometry. Ventilation and perfusion defects were analyzed blindly according to the European guidelines. Penetration grade of Technegas in V SPECT measured the degree of obstructive small airways disease. Total preserved lung function and penetration grade of Technegas in V SPECT were assessed by V/P SPECT and compared to GOLD stages and spirometry.

Results

Signs of small airway obstruction in the ventilation SPECT images were found in 92 patients. Emphysema was identified in 81 patients. Two patients had no signs of COPD, but both of them had a pulmonary embolism, and in one of them we also suspected a lung tumor. The penetration grade of Technegas in V SPECT and total preserved lung function correlated significantly to GOLD stages (r=0.63 and −0.60, respectively, P<0.0001). V/P SPECT identified pulmonary embolism in 30 patients (32%). A pattern typical for heart failure was present in 26 patients (28%). Parenchymal changes typical for pneumonia or lung tumor were present in several cases.

Conclusion

V/P SPECT, using Technegas as the functional ventilation imaging agent, is a new tool to diagnose COPD and to grade its severity. Additionally, it revealed heterogeneity of COPD caused by pulmonary comorbidities. The characteristics of these comorbidities suggest their significant impact in clarifying symptoms, and also their influence on the prognosis.

Keywords:

• V/P SPECT
• COPD
• imaging interpretation criteria
• Technegas
• pulmonary comorbidities

Acknowledgments

The authors express their gratitude to Mr Michael Guo for the excellent management of the communication between and data collection from the study centers. The authors appreciate the dedication of the patients and the personnel and physicians at the Departments of Pulmonology as well as at the Departments of Nuclear Medicine of the study centers to the study protocol and procedures. This study was financially supported by Region of Scania (ALF) and Scania University foundation Skåne University Hospital (SUS Fonder). MB has, during the last 3 years, received research grants from Cyclomedica.

Author contributions

MB and XY He designed the study. Doctors Y Chen, J Wang, XY Li, WM Shen, CZ Wang, and H Huang carried out the study, contributed to data acquisition and analysis, and provided administrative support. MB was a central reader. AL contributed to the study design, statistical analysis, and manuscript drafting. All authors read and approved the final version of the manuscript. All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.