Table 1 Multimodal criteria for the detection of abnormal findings in the internal jugular veins and in azygos vein/vertebral veins by using 2 noninvasive and 2 invasive imaging techniques

IJVs

- VH criteria 1 - presence of reflux/bidirectional flow in both sitting and supine positions

- Absent or pinpoint flow on axial TOF or TRICKS

- presence of significant stenosis (defined as venous lumen reduction ≥50 %)

- presence of significant stenosis (defined as venous lumen reduction ≥50 %)

and/or

with or without

with or without

and/or

- VH criteria 3 - presence of B-mode abnormalities (web, flap, membrane, malformed valve, septum) or CSA ≤0.3 cm²

- presence of collateral veins (external jugular veins, anterior jugular veins, facial veins, thyroid veins and deep cervical veins)

- presence of collateral veins (either epidural plexus or anterior and external jugular veins, not along the spinal cord)

- presence of various intra-luminal defects (webs, fibrotic annulus-like constrictions, flaps, septa, multiple channels)

and/or

and/or

- VH criteria 4 - absence of detectable flow

- presence of IHFD and DPL

and/or

and/or

- VH criteria 5- negative CSA

- reduced respiratory pulsatility

Azygos vein/ VVs

- VH criteria 1 - presence of reflux/bidirectional flow in both sitting and supine positions in VVs

- Absence of detectable flow in VVs

- presence of significant stenosis (defined as venous lumen reduction ≥50 %) in azygos vein

- presence of significant stenosis (defined as venous lumen reduction ≥50 %) in azygos vein

and/or

with or without

and/or

- VH criteria 4 - absence of detectable flow in VVs

- presence of collateral veins (either epidural or other collaterals)

- presence of various intra-luminal defects (webs, fibrotic annulus-like constrictions, flaps, septa, multiple channels)

and/or

- presence of IHFD and DPL

and/or

- reduced respiratory pulsatility