Question special
Chief Resident

My first question relates to criteria to conduct a CT Pulmonary-Angiography (CTPA):
1. Were additional CTPAs performed for other indications (other than the mandatory conditions listed in the supplementary appendix), as the supplementary material mentions that this was allowed at the discretion of the clinicians? If so, do you think this would have affected the primary or secondary outcomes in the study?

My second question is in regard to ventilation perfusion scanning:
2. Were any ventilation perfusion scans performed in patients with symptoms/signs suggestive of pulmonary embolus? I note that these results were not incorporated into the endpoints, and was just wondering if you could please elaborate on the rationale behind this decision? Do you think that incorporation of alternate modes of imaging into either the primary or secondary endpoints would affect the results of the study?