In the simplest terms, the interpretation of an MRV study as it relates to your meningioma
is a way of trying to detect whether or not there is outflow obstruction to blood entering from the opposite (i.e. arterial) side of the mass.
In your case the number of collateral veins (additional anatomical veins not usually present in people WITHOUT meningiomas) that have developed over time is sufficient and their pathways appear to properly drain into the STRAIGHT SINUS so there is no BACKUP or CONGESTION of bloodflow simply on the part of the meningioma.
There is a REROUTING of venous blood
in the area, however, of the mass lesion itself (and that's expected) which is what the "effacement of flow" means in the 3.5cm trajectory of the superior sagittal sinus
(i.e. no significant blood flow is found in that part of the egress channel).
In other words, your meningioma is trucking along peacefully without really disturbing the OUTFLOW or egress of the blood from its location such that oxygenation, nutrition, and metabolic waste can still be properly exchanged and executed as if it weren't there.
Hope I have answered your query. Let me know if I can assist you further.
Dr Dariush Saghafi, Neurologist