title: Characteristics of images of angiographically proven normal coronary arteries acquired by adenosine-stress thallium-201 myocardial perfusion SPECT/CT-IQ[Symbol: see text]SPECT with CT attenuation correction changed stepwise.
abstract: OBJECTIVE
  Although several studies have shown the diagnostic and prognostic value of CT-based attenuation correction (AC) of single photon emission computed tomography (SPECT) images for diagnosing coronary artery disease (CAD), this issue remains a matter of debate. To clarify the characteristics of CT-AC SPECT images that might potentially improve diagnostic performance, we analyzed images acquired using adenosine-stress thallium-201 myocardial perfusion SPECT/CT equipped with IQ[Symbol: see text]SPECT (SPECT/CT-IQ[Symbol: see text]SPECT) from patients with angiographically proven normal coronary arteries after changing the CT attenuation correction (CT-AC) in a stepwise manner.
  
  
  METHODS
  We enrolled 72 patients (Male 36, Female 36) with normal coronary arteries according to findings of invasive coronary angiography or CT-angiography within three months after a SPECT/CT study. Projection images were reconstructed at CT-AC values of (-), 40, 60, 80 and 100 % using a CT number conversion program according to our definition and analyzed using polar maps according to sex.
  
  
  RESULTS
  CT attenuation corrected segments were located from the mid- and apical-inferior spread through the mid- and apical-septal regions and finally to the basal-anterior and basal- and mid-lateral regions in males, and from the mid-inferior region through the mid-septal and mid-anterior, and mid-lateral regions in females as the CT-AC values increased. Segments with maximal mean counts shifted from the apical-anterior to mid-anterolateral region under both stress and rest conditions in males, whereas such segments shifted from the apical-septal to the mid-anteroseptal region under both stress and rest conditions in females.
  
  
  CONCLUSIONS
  We clarified which part of the myocardium and to which degree CT-AC affects it in adenosine-stress thallium-201 myocardial perfusion SPECT/CT-IQ[Symbol: see text]SPECT images by changing the CT-AC value stepwise. We also identified sex-specific shifts of segments with maximal mean counts that changed as CT-AC values increased.
authors.affiliation: Department of Radiology, Hiroshima Red Cross Hospital and Atomic-bomb Survivors Hospital, Hiroshima, Japan.
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Haruki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Nami
authors.initials: N
authors.lastname: Kozono
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Tanakamaru
authors.forename: Naomi
authors.initials: N
authors.lastname: Idei
authors.forename: Norihiko
authors.initials: N
authors.lastname: Ohashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohtsubo
authors.forename: Takenori
authors.initials: T
authors.lastname: Okada
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yasunobu
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kaseda
mesh_terms: D000241:Adenosine / Q000008:administration & dosage; D000368:Aged; D016477:Artifacts; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D064847:Multimodal Imaging / Q000295:instrumentation / Q000379:methods; D055414:Myocardial Perfusion Imaging / Q000295:instrumentation / Q000379:methods; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals; D012146:Rest; D012727:Sex Characteristics; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013312:Stress, Physiological; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D014665:Vasodilator Agents; D000241:Adenosine