title: Semi-automated algorithm for calculating heart-to-mediastinum ratio in cardiac Iodine-123 MIBG imaging.
abstract: BACKGROUND
  We have developed novel software for semi-automatically measuring heart-to-mediastinum (H/M) ratio in cardiac Iodine-123 (¹²³I)-labeled meta-iodobenzylguanidine (MIBG) imaging. Our aim is to improve the reproducibility of the H/M ratio using the semi-automated method as opposed to the manual method.
  
  
  RESULTS
  The software algorithm automatically determined the mediastinal region of interest (ROI) using information from ¹²³I-MIBG uptake of the heart, lung, liver, and thyroid after a cardiac circular ROI was manually set. A total of 37 patients who underwent both early and delayed ¹²³I-MIBG imaging was retrospectively selected. The heart-to-mediastinum (H/M) ratios were calculated by both semi-automated and manual methods and assessed for the intra- and inter-observer variability. All H/M ratios were classified into three groups: normal, slight abnormality, and severe abnormality. The H/M ratios with the new method were higher than those obtained manually (P < .001). In the test-retest reliability, the intra-class correlation coefficient from the semi-automated method showed excellent reproducibility for early (0.99) and delayed (0.99) imaging. The Bland-Altman plots demonstrated better agreement using the semi-automated method (a range of 95% limits -0.11 to 0.10) than that in the manual method (-0.34 to 0.27). The inter-observer agreement was also good using the semi-automated method (κ = 0.866).
  
  
  CONCLUSIONS
  The H/M ratio using the semi-automated method showed high reproducibility in both early and delayed imaging.
authors.affiliation: Department of Biotracer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan. okuda@nmd.m.kanazawa-u.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Okuda
authors.forename: Kenichi
authors.initials: K
authors.lastname: Nakajima
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hosoya
authors.forename: Takehiro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Konishi
authors.forename: Kosuke
authors.initials: K
authors.lastname: Matsubara
authors.forename: Shinro
authors.initials: S
authors.lastname: Matsuo
authors.forename: Seigo
authors.initials: S
authors.lastname: Kinuya
mesh_terms: D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics; D000465:Algorithms; D005260:Female; D006331:Heart Diseases / Q000000981:diagnostic imaging* / Q000378:metabolism; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008482:Mediastinum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D015588:Observer Variation; D010363:Pattern Recognition, Automated / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine