title: Ventilation/perfusion SPECT in chronic obstructive pulmonary disease: an evaluation by reference to symptoms, spirometric lung function and emphysema, as assessed with HRCT.
abstract: OBJECTIVE
  Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation which is not fully reversible. Despite the heterogeneity of COPD, its diagnosis and staging is currently based solely on forced expiratory volume in 1 s (FEV(1)). FEV(1) does not explain the underlying pathophysiology of airflow limitation. The relationship between FEV(1), symptoms and emphysema extent is weak. Better diagnostic tools are needed to define COPD. Tomographic lung scintigraphy [ventilation/perfusion single photon emission tomography (V/P SPECT)] visualizes regional V and P. In COPD, relations between V/P SPECT, spirometry, high-resolution computed tomography (HRCT) and symptoms have been insufficiently studied. The aim of this study was to investigate how lung function imaging and obstructive disease grading undertaken using V/P SPECT correlate with symptoms, spirometric lung function and degree of emphysema assessed with HRCT in patients with COPD.
  
  
  METHODS
  Thirty patients with stable COPD were evaluated with the Medical Research Council dyspnoea questionnaire (MRC) and the clinical COPD questionnaire (CCQ). Spirometry was performed. The extent of emphysema was assessed using HRCT. V/P SPECT was used to assess V/P patterns, total reduction in lung function and degree of obstructive disease.
  
  
  RESULTS
  The total reduction in lung function and degree of obstructive disease, assessed with V/P SPECT, significantly correlated with emphysema extent (r = 0.66-0.69, p < 0.0001) and spirometric lung function (r = 0.62-0.74, p < 0.0005). The correlation between emphysema extent and spirometric lung function was weaker. No correlation between MRC, CCQ and objective measurements was found.
  
  
  CONCLUSIONS
  V/P SPECT is sensitive to early changes in COPD. V/P SPECT also has the possibility to identify comorbid disease. V/P SPECT findings show a significant correlation with emphysema extent and spirometric lung function. We therefore recommend that scintigraphic signs of COPD, whenever found, should be reported. V/P SPECT can also be used to categorize the severity of functional changes in COPD as mild, moderate or severe.
authors.affiliation: Department of Clinical Physiology, Institution of Clinical Sciences, Lund University, Skåne University Hospital, 221 85 Lund, Sweden. jonas.jogi@med.lu.se
authors.forename: Jonas
authors.initials: J
authors.lastname: Jögi
authors.forename: Marie
authors.initials: M
authors.lastname: Ekberg
authors.forename: Björn
authors.initials: B
authors.lastname: Jonson
authors.forename: Gracijela
authors.initials: G
authors.lastname: Bozovic
authors.forename: Marika
authors.initials: M
authors.lastname: Bajc
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D011656:Pulmonary Emphysema / Q000150:complications*; D013147:Spirometry; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio