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Conflicting results between V/Q SPECT and angioscan in pulmonary embolism: what to do?


The objective of this study is to determine the final clinical diagnosis of patients who underwent the double investigation for pulmonary embolism with conflicting results. Pulmonary embolism is a prevalent pathology in the emergency department (ED). A certain proportion of patients undergo a double radiological investigation (V/Q SPECT and angioscan), which incurs higher costs and X-ray doses. However, no study to date has addressed this issue.


This retrospective study included patients who underwent a double investigation in the ED of Hôpital du Sacré-Coeur de Montréal from April 2008 to October 2012. Patients were selected from a computerized database of medical prescriptions (MediaMed Technologie). Data were then extracted from the patient's files: patient characteristics, radiology report, diagnosis and treatment. Descriptive statistics were conducted.


In all, 125 patients underwent the double investigation. Our sample had a mean age of 63.1 years (SD ±18.6) and was composed of 82 (65.6%) women. One hundred and fifteen patients (92%) underwent the V/Q SPECT first. The result of 66 (52.8%) SPECT was intermediate or indeterminate. The final diagnosis was pulmonary embolism for 23 patients (18.4%). A significant proportion of patients (19, 38.0%) had conflicting results with the two tests. In this subpopulation, four (21.1%) had a final diagnosis of pulmonary embolism. In the 16 patients with a result of high probability V/Q SPECT and negative angioscan, one (6.3%) had a final diagnosis of pulmonary embolism, but three (100%) with low probability SPECT and positive angioscan were given this final diagnosis.


Most patients underwent the double investigation because of intermediate or indeterminate V/Q SPECT results. In case of conflicting results, clinicians based their decision on the angioscan. In future studies, it would be useful to identify contributing factors for this discordance.

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Correspondence to JM Martel.

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Martel, J., Nadeau, M., Daoust, R. et al. Conflicting results between V/Q SPECT and angioscan in pulmonary embolism: what to do?. Crit Care 17, P230 (2013).

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  • Emergency Department
  • Retrospective Study
  • High Probability
  • Pulmonary Embolism
  • Clinical Diagnosis