Feasibility of quantitative measurement of the superior ophthalmic vein flow by phase contrast MRI.

Abstract

 

Purpose

 

Phase contrast magnetic resonance imaging (PC MRI) is a non invasive functional imaging that has been applied recently to orbital studies. However no quantitative analysis of the orbital venous flow has been published yet, and only few of the ophthalmic artery (OA) flow. Our purpose was to assess the feasibility of superior ophthalmic vein flow analysis, and measure OA blood flow, by PC MRI.

 

Methods

 

A PC MRI with cardiac synchronization was performed for 13 healthy volunteers on a 3 Tesla MRI. A measurement plan was placed perpendicularly to the orbital part of the OA and the SOV, using a T2-weighed sequence. The parameters of the PC MRI sequence were a field of view of 120x120 mm, a matrix of 256x128 (reconstructed 256), a slice thickness of 5 mm, 32 phases per cardiac cycle. The acquisition time was less than 2 minutes. Segmentations of vascular structures were obtained with a dedicated software to calculate blood flow curves.

 

Results

 

The flow measurement in the ophthalmic artery was possible on 92% of the acquisitions. The OA mean flow was 11 ± 6 mL/min. The systolic and diastolic OA flow were 22 ± 10 mL/min and 4 ± 5 mL/min respectively. The flow measurement in the SOV was only possible on 22% of the acquisitions. Its mean flow was 13 ± 7 mL/min.

 

Conclusions

 

PC MRI seems a suitable method to assess OA and SOV flow curves during cardiac cycle. Arterial flow measurements are coherent with those published. Venous analysis was less predictable than OA, probably due to the complexity of the venous tree. PC MRI is a rapid and non invasive method that could easily apply for clinical imaging applications. It could open new insights to study intracranial hypertension or glaucoma by quantification of the global arterio-venous flow of the eye.  

 

A coronal plane of acquisition has been placed perpendicularly to the direction of the ophthalmic artery (OA) or the superior ophthalmic vein (SOV), in order to acquire phase contrast magnetic resonance imaging (PC MRI) images. The region of interest is selected and segmented. The segmentation is applied on the whole sequence i.e. 32 images corresponding to 32 phases of an average cardiac cycle. The blood flow is calculated and the software provides the curve of the evolution of the flow during cardiac cycle.

 

 

Evolution of flow (in mL/min) during cardiac cycle in right and left superior ophthalmic vein of one healthy subject.