“IMPRESSION: There is prominence of the vasculature without frank pulmonary edema.”

“Prominence of the vasculature” is an imprecise description of a radiographic finding, not a diagnostic impression.
 
The example sentence can be interpreted as either normal or abnormal. If there is uncertaintly I think it’s better to be upfront about it: “Early pulmonary edema is possible.” 

Does “prominent” mean normal or abnormal? Cephalized, redistributed flow to the upper lobes is a well-known radiographic finding usually thought to result from early lower lobe intersitial edema. If by “prominent” the author means “cephalized”, then pulmonary edema is likely in progress.

If “frank pulmonary edema” is intended to mean alveolar edema, it’s more precise to say alveolar or airspace edema, since “pulmonary edema” encompasses both tissue (interstitial) and airspace (alveolar) edema.

Considering edema distribution, heart size/contour, mediastinal width, pleural and subpleural spaces I usually try to give my impression as to cardiogenic or noncardiogenic edema. I’d rewrite the examples sentence something like: “Possibly early cardiogenic interstitial edema.”  The implication being that clinical correlation for dyspnea/orthopnea etc. is needed. I don’t feel the need to say “clinical correlation required…” in this circumstance, particularly if the provided history is “SOB”.