A good reference from Dr. Siskin's group.Review of Venous Anatomy for Venographic Interpretation in Chronic Cerebrospinal Venous Insufficiency
Fig 3 shows the effect of head rotation, where the stenosis is still visible in both positions but the vein has more flow when rotated contralaterally. (Ipsilateral is same side, contralateral is the other side. Looking to the left would maximize your right jugular, looking to the right would minimize your right jugular.)Taal et al (18) found clinically significant anatomic abnormalities including stenoses and/or angulation in the central veins (IJVs, brachiocephalic veins, and SVC) in as many as 30% of patients undergoing dialysis with no history of previous catheter placement. The use of CT scans to measure the diameters of the right and left IJV showed that 80.5% of individuals have a smaller IJV on the left (5, 19). The diameter of the IJV is independent of age and sex (20).
There are many factors that can determine the size of the IJV. These include hydration status, cardiac status and intrathoracic pressure, head position, and anatomic compression by adjacent structures in the neck (21). Certain positional maneuvers can maximize the cross-sectional area of the IJV, including head rotation to the contralateral side (Fig 3) and placement of the patient in the Trendelenburg position (22, 23). In fact, head rotation to the ipsilateral side causes a significant reduction of the mean diameter of the ipsilateral IJV, even approaching complete occlusion (23). The size of the IJV can be further complicated by the occurrence of jugular phlebectasia, which is defined as focal dilation of the inferior jugular bulb, or the area of the vein located inferior to the valves (21). This is more common on the right than the left because intrathoracic pressure may be more directly transmitted to the right side than to the left, possibly because of the shorter length of the right brachiocephalic vein and the possible presence of valves in the left brachiocephalic vein (24).
I would have liked to have seen the renal and iliac veins included too.