• Marika Bajc, Hanna Markstad, Linnea Jarenbäck, Ellen Tufvesson, Leif Bjermer, and Jonas Jögi.
• Department of Clinical Physiology and Nuclear Medicine, Department of Imaging and Physiology, Skåne University Hospital and Lund University, 22185, Lund, Sweden, marika.bajc@med.lu.se.
• Ann Nucl Med. 2015 Jan 1; 29 (1): 91-9.

UnlabelledThe 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.

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