Quantification of blood flow in the superior ophthalmic vein using phase contrast magnetic resonance imaging

Phase contrast magnetic resonance imaging (PC MRI), a validated, non-invasive technique for measuring intracranial blood and cerebrospinal flows, has been recently applied to studies of blood flow of the ophthalmic artery (OA). This study evaluated PC-MRI's ability to quantify blood flow in the superior ophthalmic vein (SOV). We analyzed with 3 T PC MRI the blood flow in the SOV in 11 healthy subjects and, for comparison purpose, in the OA. Segmentation software was used to analyze the PC images and quantify the variation in blood flow over the cardiac cycle in each of the vessels. The anatomy of the orbital veins was also assessed. We were able to measure the blood flow in 19 SOV; the mean ± standard deviation (SD) SOV flow was 9.13 ± 7.10 mL/min with a mean ± SD variation of flow during cardiac cycle of 8.45 ± 4.90 mL/min. The mean ± SD flow in the OA was 12.83 ± 8.36 mL/min. The SOV was constantly present, with a mean cross-sectional area of 2.43 mm². A medium and an inferior ophthalmic veins were found in 5 and 3 orbits, respectively. In conclusion, PC MRI is able to measure SOV as well as OA flows. To the best of our knowledge, the present study is the first to provide quantitative SOV blood flow values using PC MRI. Investigations of hydrocephalus, intracranial hypertension and even glaucoma might be facilitated by the application of this quantitative imaging modality.