Grading obstructive lung disease using tomographic pulmonary scintigraphy in patients with chronic obstructive pulmonary disease (COPD) and long-term smokers

Abstract

The severity of chronic obstructive lung disease (COPD) is defined by the degree of flow limitation measured as forced expiratory volume in 1 s, which mainly reflects impairment of large and intermediate airways. However, COPD is primarily a small airways disease. Therefore, better diagnostic tools are needed. Ventilation-Perfusion (V/P) SPECT is a sensitive method to detect obstructive lung changes but criteria for staging airway obstruction are missing.PurposeTo define and validate criteria to stage COPD using V/P SPECT.Method74 subjects (healthy non-smokers, healthy smokers or with stable COPD) were included. All were examined with V/P SPECT in a hybrid SPECT/CT system. Spirometry was performed and patients were evaluated with the clinical COPD questionnaire (CCQ). V/P SPECT was interpreted independently. Preserved lung function (%) was evaluated. The degree of airway obstruction on V/P SPECT was graded according to newly-developed grading criteria. The degree of airway obstruction was graded from normal (0) to severe (3). The airway obstructivity-grade and degree of preserved lung function were compared to GOLD, CCQ and LDCT emphysema extent.ResultsObstructivity-grade (r = 0.66, P < 0.001) and the degree of preserved lung function (r = −0.70, P < 0.001) both correlated to GOLD. Total preserved lung function decreased in relation to higher GOLD stage. There was a significant difference between healthy controls and apparently healthy long time smokers both regarding obstructivity-grade (P = 0.001) and preserved lung function (P < 0.001). Long-time smokers did not differ significantly from GOLD 1 COPD patients (P = 0.14 and P = 0.55 for obstructivity-grade and preserved lung function, respectively). However, patients in GOLD 1 differed in obstructivity-grade from non-smoking controls (P = 0.02).ConclusionFunctional imaging with V/P SPECT enables standardized grading of airway obstruction as well as reduced lung function, both of which correlate with GOLD stage. V/P SPECT shows that long-term smokers in most cases have signs of ventilatory impairment and airway obstruction not shown by spirometry.

Correlation of 68Ga Ventilation–Perfusion PET/CT with Pulmonary Function Test Indices for Assessing Lung Function

“…Advances have improved the diagnostic performances of the test especially in pulmonary embolism diagnosis (23,24) and also in lung functional assessment (25,26). However, the relatively low resolution of SPECT imaging makes accurate delineation and quantification of lung functional volumes difficult (11).…”

Ventilation/perfusion SPECT or SPECT/CT for lung function imaging in patients with pulmonary emphysema?

“…Over the last decades, the advent of ventilation/perfusion single photon emission computed tomography (V/P SPECT) has improved the diagnostic value of lung imaging by nuclear medicine methods [1,2]. Further benefits are described for the use of hybrid scanners such as PET/CT and SPECT/CT [3][4][5].…”

Lung Volume Reduction in Pulmonary Emphysema from the Radiologist’s Perspective

“…Ventilation/perfusion-SPECT (V/P single-photon emission computed tomography) is known as a method for diagnosing pulmonary embolisms, among other conditions. V/P-SPECT was also used in multiple studies to detect and grade pulmonary emphysema [54,55]. As described above, COPD is diagnosed with the aid of spirometry, which reveals obstructive changes in primarily major and intermediate airways through FEV 1 .…”

“…Because, however, the pathological correlate primarily exhibited by COPD is an obstruction of the minor airways, a better diagnostic method would be desirable. V/P-SPECT can possibly reveal these changes in the minor airways [55]. Individual studies have shown that V/P-SPECT is more sensitive than lung function tests and high-resolution CT [55].…”

“…V/P-SPECT can possibly reveal these changes in the minor airways [55]. Individual studies have shown that V/P-SPECT is more sensitive than lung function tests and high-resolution CT [55]. However, the method is still highly experimental, and major comparative studies are required before a definitive assessment can be made regarding its diagnostic accuracy.…”