title: Cut-off value for normal versus abnormal right-to-left shunt percentages using (99m)Tc-macroaggregated albumin.
abstract: OBJECTIVE
  To determine the cut-off value for distinguishing a normal versus an abnormal right-to-left shunt percentage on lung perfusion scintigraphy using (99m)Tc-macroaggregated albumin (MAA).
  
  
  METHODS
  Fifty-three patients (eight patients with a right-to-left shunt and 45 without a right-to-left shunt) who underwent MAA whole-body imaging for the evaluation of right-to-left shunts were divided into group 1 (eight patients with brain MAA uptake) and group 2 (45 patients without brain MAA uptake). Moreover, group 2 was subdivided into two categories (groups 2a and 2b) based on the results of lung computed tomography, electrocardiography examinations, and pulmonary function tests. The average and standard deviation (SD) of each group were compared. In addition, we estimated the cut-off value for a normal right-to-left shunt percentage using whole-body imaging.
  
  
  RESULTS
  The average right-to-left shunt percentage values and SD were 23.67±12.17% in group 1, 6.68±1.04% in group 2a, and 6.60±0.84% in group 2b. The shunt percentages of groups 2a and 2b were not significantly different (P=0.77). The estimated normal value (mean±2 SD) of group 2 was 6.64±0.94%. Meanwhile, the cut-off value was estimated as 10% based on the distributions of MAA shunt percentages for groups 1 and 2.
  
  
  CONCLUSIONS
  The normal range (mean±2 SD) was 6.64±1.88%. The cut-off value for the normal right-to-left shunt percentage in MAA scintigraphy was 10%.
authors.affiliation: Department of Radiology, National Center of Neurology and Psychiatry, Tokyo, Japan. itoukimiteru@yahoo.co.jp
authors.forename: Kimiteru
authors.initials: K
authors.lastname: Ito
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kurihara
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishibashi
authors.forename: Miyako
authors.initials: M
authors.lastname: Morooka
authors.forename: Takuya
authors.initials: T
authors.lastname: Mitsumoto
authors.forename: Ryogo
authors.initials: R
authors.lastname: Minamimoto
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kubota
mesh_terms: D000328:Adult; D000368:Aged; D001692:Biological Transport; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D003326:Coronary Circulation; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging / Q000378:metabolism; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000592:standards*; D012016:Reference Values; D013668:Technetium Tc 99m Aggregated Albumin / Q000378:metabolism; D051598:Whole Body Imaging
chemical_list: D013668:Technetium Tc 99m Aggregated Albumin