title: Enhanced perfusion defect clarity and inhomogeneity in smokers' lungs with deep-inspiratory breath-hold perfusion SPECT images.
abstract: OBJECTIVE
  Deep-inspiratory breath-hold (DIBrH) Tc-99m-macroaggregated albumin (MAA) SPECT images were developed to accurately evaluate perfusion impairment in smokers' lungs.
  
  
  METHODS
  DIBrH SPECT was performed in 28 smokers with or without low attenuation areas (LAA) on CT images, using a triple-headed SPECT system and a laser light respiratory tracking device. DIBrH SPECT images were reconstructed from every 4 degrees projection of five adequate 360 degrees projection data sets with almost the same respiratory dimension at 20 sec DIBrH. Perfusion defect clarity was assessed by the lesion (defect)-to-contralateral normal lung count ratios (L/N ratios). Perfusion inhomogeneity was assessed by the coefficient of variation (CV) values of pixel counts and correlated with the diffusing capacity of the lungs for carbon monoxide/alveolar volume (DLCO/VA) ratios. The results were compared with those on conventional images.
  
  
  RESULTS
  Five DIBrH projection data sets with minimal dimension differences of 2.9+/-0.6 mm were obtained in all subjects. DIBrH images enhanced perfusion defects compared with conventional images, with significantly higher L/N ratios (P<0.0001), and detected a total of 109 (26.9%) additional detects (513 vs. 404), with excellent inter-observer agreement (kappa value of 0.816). CV values in the smokers' lungs on DIBrH images were also significantly higher compared with those on conventional images (0.31+/-0.10 vs. 0.19+/-0.06, P<0.0001). CV values in smokers on DIBrH images showed a significantly closer correlation with DLCO/VA ratios compared with conventional images (R = 0.872, P<0.0001 vs. R=0.499, P<0.01).
  
  
  CONCLUSIONS
  By reducing adverse effect of respiratory motion, DIBrH SPECT images enhance perfusion defect clarity and inhomogeneity, and provide more accurate assessment of impaired perfusion in smokers' lungs compared with conventional images.
authors.affiliation: Department of Radiology, Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan. sugar@po.cc.yamaguchi-u.ac.jp
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Suga
authors.forename: Kawakami
authors.initials: K
authors.lastname: Yasuhiko
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Iwanaga
authors.forename: Norio
authors.initials: N
authors.lastname: Hayashi
authors.forename: Tomio
authors.initials: T
authors.lastname: Yamashita
authors.forename: Naofumi
authors.initials: N
authors.lastname: Matsunaga
mesh_terms: D016477:Artifacts; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D001239:Inhalation; D007834:Lasers; D008168:Lung / Q000000981:diagnostic imaging*; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D009068:Movement; D011652:Pulmonary Circulation; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012119:Respiration; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects*; D014652:Vascular Diseases / Q000000981:diagnostic imaging* / Q000209:etiology