Lung scintigraphy for pulmonary embolism diagnosis during the COVID-19 pandemic: does the benefit-risk ratio really just
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LETTER TO THE EDITOR
Lung scintigraphy for pulmonary embolism diagnosis during the COVID-19 pandemic: does the benefit-risk ratio really justify omitting the ventilation study? Pierre-Yves Le Roux 1
&
Grégoire Le Gal 2 & Pierre-Yves Salaun 1
Received: 7 July 2020 / Accepted: 15 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Dear Sir, The COVID-19 pandemic is challenging nuclear medicine facilities around the world. One important complication associated with COVID-19 disease is coagulopathy, with an increased risk of venous thromboembolism [1]. Lung ventilation/perfusion (V/Q) scintigraphy is a well-established test for pulmonary embolism (PE) diagnosis. Lung scintigraphy has been validated in several large multicenter management outcome studies [2], in which the V/Q scan was interpreted based on the recognition of the well-known perfusion mismatched defect, i.e., a perfusion defect with normal ventilation. With the recent COVID-19 outbreak, it has been repeatedly proposed in the nuclear medicine community to omit the ventilation scintigraphy and to only perform a perfusion planar scan or a perfusion SPECT/CT, in patients with suspected acute PE [3–6]. The rational for this approach is to minimize potential exposure to aerosolized secretions of others in the nuclear medicine department. Rightly, the inhalation procedure increases the potential risk of contamination by the expired air and the aerosol secretion, especially if the patient coughs. For these reasons, adequate personal protective equipment is required for healthcare workers. On the other hand, not performing a ventilation scan is associated with a high risk of false positive result. In a retrospective analysis of 393 patients with suspected PE assessed This article is part of the Topical Collection on Letter to the Editor * Pierre-Yves Le Roux [email protected] 1
Service de médecine nucléaire, CHRU de Brest, EA3878 (GETBO), Université de Brest, CHRU Morvan, Médecine nucléaire, 2 avenue Foch, 29609 Brest Cedex, France
2
Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada
by V/Q SPECT, 42 out of 283 (15%) patients with a negative V/Q SPECT would have been wrongly diagnosed with PE and would have been unduly exposed to anticoagulant therapy by substituting the ventilation SPECT by a low-dose CT [7]. Similarly, in a series of 81 patients from Gutte et al., specificity decreased from 100 with V/Q SPECT/CT to 51% with a Q SPECT/CT approach, with 20 patients unduly diagnosed with PE by omitting the ventilation [8]. In another study including 93 patients, 12 out of 69 (17%) negative V/Q SPECT were falsely positive using a P SPECT/CT approach without ventilation [9]. Accordingly, Q SPECT/CT is not an accurate diagnostic test for PE diagnosis as a positive result has an unacceptably high likelihood to be a false positive result. What are the implications of a false positive diagnostic test in a patient with suspected acute PE? First, anticoagulant therapy is associated with
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