Yongquan Ye, Presenter: Nothing to Disclose

Zhen Wu PhD, Abstract Co-Author: Nothing to Disclose

E. Mark Haacke PhD, Abstract Co-Author: Research Grant, Biogen Idec Inc President, Magnetic Resonance Innovations, Inc

Retrobulbar vessels, such as ophthalmic artery (OA) and vein (OV), central retinal artery (CRA), posterior ciliary arteries (PCA) and lacrimal artery (LA), are critical to maintain the eye’s normal function. Disrupted blood flow in these vessels can lead to severe vision loss. However, these vessels are difficult to image with MRI. Here we demonstrate a novel water selective excitation method, namely Binomial Off-Resonant Rectangular (BORR) pulse, for obtaining high resolution retrobulbar vascular maps. 

Nine healthy volunteers (5 males, 31±3 y/o) were enrolled in the study with written consents. All data were collected on a Siemens 3T Verio scanner with product 32ch head coil. The BORR GRE sequence was scanned sagitally with TR/TE = 11/3ms, 0.5mm isotropic voxels; BORR pulse duration τ= 1.6ms, flip angle = 12°, and frequency offset Δf = 140Hz. This configuration gives whole brain coverage and excellent fat suppression. For comparison, 3D TOF MRA (with and without fat saturation [FS], or water excitation [WE]), 2D TOF, Linear Subtraction (LS) MRA and CE MRA were also performed. All scans were configured to have similar parameters (e.g. voxel size, bandwidth, etc.). All final results were reoriented to axial plane and processed with Maximal Intensity Projection (MIP) over a 4mm thickness.    

As shown in the figure, the BORR pulse reliably suppresses all orbital fats, while preserving high vessel signal with sharp edges. In contrast, none of other MRA methods, including CE-MRA and LS MRA which have proven to work well for cerebral vessels, achieved similar performance in showing the vessels. 

With our new BORR method, we have shown for the first time the high resolution MR images of the retrobulbar vessels, which has not been revealed by any existing MRA methods. This is because these vessels are buried in fatty tissues that show high signal in most MRA methods, and routine fat suppression or water excitation approaches also affect blood signal. The BORR method, on the other hand, has very robust and thorough fat suppression while preserving high blood signal. Therefore we have demonstrated the promising capacity for imaging retrobulbar vessels of the BORR method. 

We demonstrate a novel MRA method to reveal retrobulbar orbital vessels with high resolution, clearly revealing major vessels such as OA, OV, PCA and CRA to enable direct evaluation of the blood supply to the eyes.

Ye, Y, Wu, Z, Haacke, E, Novel Binomial Off-Resonant Rectangular (BORR) Pulse for MRI Retrobulbar Vessel Imaging.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009503.html