title: 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.
  
  
  OBJECTIVE
  To define and validate criteria to stage COPD using V/P SPECT.
  
  
  METHODS
  74 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.
  
  
  RESULTS
  Obstructivity-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).
  
  
  CONCLUSIONS
  Functional 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.
authors.affiliation: 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.
authors.forename: Marika
authors.initials: M
authors.lastname: Bajc
authors.forename: Hanna
authors.initials: H
authors.lastname: Markstad
authors.forename: Linnea
authors.initials: L
authors.lastname: Jarenbäck
authors.forename: Ellen
authors.initials: E
authors.lastname: Tufvesson
authors.forename: Leif
authors.initials: L
authors.lastname: Bjermer
authors.forename: Jonas
authors.initials: J
authors.lastname: Jögi
mesh_terms: D000368:Aged; D000402:Airway Obstruction / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012720:Severity of Illness Index; D012907:Smoking / Q000473:pathology* / Q000503:physiopathology; D013147:Spirometry; D011795:Surveys and Questionnaires; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*