Quantitation of flow in the superior sagittal sinus performed with cine phase-contrast MR imaging of healthy and achondroplastic children

BACKGROUND AND PURPOSE: Cine phase-contrast (PC) MR imaging is a convenient and effective method for measuring volumetric flow rates in vivo. We attem pted to evaluate changes in blood flow in the superior sagittal sinus (SSS) in children and to assess the hypothesis that restricted venous outflow at tributable to stenosis of the jugular vein causes hydrocephalus in achondro plasia. METHODS: Blood flow in the SSS was measured by using cine PC MR imaging wit h a 1.5-T scanner. After validation, 35 neurologically healthy children as well as eight children with achondroplasia (five with hydrocephalus) and tw o children with obstructive hydrocephalus were studied. Average flow veloci ty over the cardiac cycle and volumetric flow rate in the SSS were obtained . The data for healthy children were plotted as a function of age, and refe rence values were defined by using a five-point smoothing. RESULTS: In healthy children, flow velocity ranged from 92 to 196 mm/s (mea n, 136), and flow rate from 189 to 688 mL/min (mean, 484). The flow rate sh owed changes statistically related to age. It rapidly increased during the first 2 years and reached a peak by 6 to 8 years of age. The flow velocity showed a similar pattern, but not with significant correlation. in all case s of achondroplasia with hydrocephalus, both flow values were reduced below the reference values minus one standard deviation. In cases of achondropla sia without hydrocephalus, and in obstructive hydrocephalus, the values wer e not reduced. CONCLUSION: Blood flow in the SSS reflects brain maturation. Hydrocephalus associated with achondroplasia was found to be closely related to reduced f low in the SSS, which supports the hypothesis that restricted venous outflo w causes hydrocephalus in cases of achondroplasia.