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FIG 1. Case of a 66-year-old woman.
A and B, Coronal 2D PC MR venograms obtained during regular breathing (A) and breath holding (B). The right sigmoid sinus is clearly depicted on the regular-breathing image. Signal intensity decreases with breath holding. The left transverse and sigmoid sinuses are not seen on the regular-breathing image. However, the signal intensities of these veins (arrows) are depicted on the breath-holding image.
C, Velocity image of the peripheral pulse–triggered 2D PC sequence shows the signal intensities of the sigmoid sinuses. The signal intensity of the right sigmoid sinus decreases during breath holding. However, increased signal intensity is observed in the left sigmoid sinus with breath holding, compared with regular breathing. These flow changes of the sinuses are consistent with the results on the MR venograms. 
indicates the right sigmoid sinus (regular breathing); •, the right sigmoid sinus (breath holding); 
, the left sigmoid sinus (regular breathing); 
, the left sigmoid sinus (breath holding).
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