title: Spontaneous abrupt changes in the distribution of ventilation: a cause for apparent mismatching on ventilation/perfusion scintigraphy.
abstract: A defect seen in the perfusion scan in a region of lung that is normally ventilated is usually interpreted as indicating pulmonary vascular disease. Since the distribution of 99Tcm macro-aggregated albumin (MAA) represents the distribution of perfusion (Q) only at the time of MAA injection, the assumption is required that the distribution of ventilation (V) remains unchanged between MAA injection and the commencement of imaging. We report the V/Q scintigraphic findings in six patients (including four children), in whom this assumption could not be sustained. Thus ventilation imaged with 81Krm was seen to change during image acquisition in lobes that showed perfusion abnormalities. In some, but not all, views the appearances were typical for pulmonary vascular disease, which might easily have been misdiagnosed if the changes in the distribution of ventilation had not announced themselves by occurring during image acquisition. A ventilation image obtained immediately before injection of 99Tcm-MAA may be useful.
authors.affiliation: Department of Paediatric Radiology, Hospital for Sick Children, London.
authors.forename: A M
authors.initials: AM
authors.lastname: Peters
authors.forename: I
authors.initials: I
authors.lastname: Gordon
authors.forename: A M
authors.initials: AM
authors.lastname: Kaiser
authors.forename: R N
authors.initials: RN
authors.lastname: Arnot
authors.forename: J P
authors.initials: JP
authors.lastname: Lavender
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D011877:Radionuclide Imaging; D013668:Technetium Tc 99m Aggregated Albumin; D014692:Ventilation-Perfusion Ratio
chemical_list: D013668:Technetium Tc 99m Aggregated Albumin