title: Tc-99m MAA total-body imaging to detect intrapulmonary right-to-left shunts and to evaluate the therapeutic effect in pulmonary arteriovenous shunts.
abstract: The appearance of radiotracer in the systemic circulation to document the visualization of the brain, kidneys, and spleen after intravenous administration of Tc-99m MAA indicates right-to-left shunts because MAA particles (20-60 microns) are supposedly trapped in the pulmonary bed (less than 15 microns). Six hypoxemia patients (1 male, 5 females; age range, 12-52 years) with intrapulmonary right-to-left shunts were evaluated by Tc-99m MAA dynamic perfusion imaging and total-body scans. Tc-99m MAA total-body imaging of the six patients with intrapulmonary right-to-left shunts (3 patients with chronic liver disease/cirrhosis of the liver and 3 patients with pulmonary arteriovenous fistulae) revealed significant radiotracer uptake in extrapulmonary organs such as the brain, kidneys, and spleen; a shunt ratio, estimated by a semiquantitative method, ranged from 17.8% to 52%. All dynamic pulmonary perfusion scans showed a normal sequence of cardiopulmonary flow without intracardiac shunts. Three patients with pulmonary arteriovenous fistulae underwent a second Tc-99m MAA total-body imaging after embolization therapy (2 patients) or lobectomy (1 patient). The result in lobectomized patients were negative for uptake in extrapulmonary organs; the two patients who underwent embolization therapy demonstrated only mild improvement. As a consequence of these findings, the authors conclude that Tc-99m MAA total-body imaging can be used for the diagnosis of intrapulmonary right-to-left shunts, as well as for the evaluation of postshunt therapy.
authors.affiliation: Department of Nuclear Medicine, Peijing Union Medical College Hospital, Beijing, China.
authors.forename: G
authors.initials: G
authors.lastname: Lu
authors.forename: W J
authors.initials: WJ
authors.lastname: Shih
authors.forename: C
authors.initials: C
authors.lastname: Chou
authors.forename: J Y
authors.initials: JY
authors.lastname: Xu
mesh_terms: D000328:Adult; D001164:Arteriovenous Fistula / Q000151:congenital / Q000000981:diagnostic imaging* / Q000628:therapy; D001165:Arteriovenous Malformations / Q000000981:diagnostic imaging*; D002648:Child; D004621:Embolization, Therapeutic; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000000981:diagnostic imaging; D008168:Lung / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D011013:Pneumonectomy; D011651:Pulmonary Artery / Q000002:abnormalities; D011667:Pulmonary Veins / Q000002:abnormalities; D011877:Radionuclide Imaging; D013668:Technetium Tc 99m Aggregated Albumin
chemical_list: D013668:Technetium Tc 99m Aggregated Albumin