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Rapid, high-resolution imaging of the central veins in multiple sclerosis at 1.5T, 3T, and 7T
Pascal Sati1, Sunil Patil2, Souheil I Inati3, Govind Nair1, Gunnar Krueger4, and Daniel S Reich1

1Translational Neuroradiology Section, NINDS, National Institutes of Health, Bethesda, MD, United States, 2Siemens Medical Solutions, HC NAM USA DI MR COLLAB, Bethesda, MD, United States, 3InatiAnalytics, Potomac, MD, United States, 4Siemens Medical Solutions, HC NAM USA DI MR COLLAB NE, Boston, MA, United States

Synopsis

The central vein sign (CVS) detected by magnetic resonance imaging (MRI) may aid with the diagnosis of multiple sclerosis (MS). The ability to detect central veins in the brain at any magnetic field strengths would open the pathway for future large-scale research studies, and potentially routine clinical use, of the CVS for MS diagnosis. In this study, a fast high-isotropic-resolution, whole-brain T2*-weighted segmented echo-planar-imaging acquisition was implemented at 1.5T, 3T and 7T. Central veins inside multiple sclerosis lesions were detected at all three different field strengths.

Introduction

Recent research investigating various neurological conditions has accumulated evidence that the central vein sign (CVS) detected by magnetic resonance imaging (MRI) may have the ability to accurately differentiate multiple sclerosis (MS) from its mimics1. However, an imaging strategy, which would allow detection of the CVS at any magnetic field strengths in a clinically compatible time, is still lacking.

Methods

A fast (< 6 min), high-isotropic-resolution, whole-brain T2*-weighted segmented echo-planar-imaging (EPI) prototype sequence was implemented with approximate SNR-matched protocols at 1.5T, 3T and 7T (MAGNETOM Aera, Siemens, Erlangen, Germany; 1.5T, voxel size = 0.75 mm3, TR = 64 ms, TE = 37 ms, FA = 10 deg, EPI factor = 15), (MAGNETOM Skyra, Siemens, Erlangen, Germany; 3T, voxel size = 0.65 mm3, TR = 64 ms, TE = 35 ms, FA = 10 deg, EPI factor = 15) and on a 7T research system (Siemens, Erlangen, Germany; voxel size = 0.5 mm3, TR = 52 ms, TE = 23 ms, FA = 10 deg, EPI factor = 15]. Three subjects (one healthy volunteer and two MS patients) were scanned on the 3 different MRI scanners. At both 1.5T and 3T, T2* acquisition for the MS patients was performed during the injection of gadolinium-based contrast agent (Gadavist, Bayer HealthCare Pharmaceuticals Inc., Whippany, NJ). At 7T, only native images were acquired.

Results

High-quality T2*-weighted brain images were obtained at 3 different magnetic field strengths in all subjects (Figure 1). Unlike standard FLAIR contrast, T2*-weighted contrast displays the central vein inside MS lesions (Figure 2), and can be combined to produce FLAIR* images2. The use of isotropic voxel dimensions for the T2* acquisition enabled the multi-planar reconstruction of the images, allowing straightforward detection of the central vein regardless of its orientation in the brain (Figure 3). In this pilot study, a total of 5 focal MS lesions (diameter > 3 mm) with a central vein were detected on all 3 T2*-w scans (1.5T, 3T and 7T) in the MS patients. However, the increase in image resolution and improved T2*-weighting at 7T allowed to readily detect the central vein without the use of contrast agent (Figure 3).

Discussion/Conclusion

This pilot study demonstrates the feasibility of imaging central veins in MS brains at 1.5T, 3T and 7T, in a clinically compatible time using a strategy based on segmented EPI. This approach opens the pathway for establishing a standardized MRI acquisition for future large-scale research studies, and potentially routine clinical use, of the CVS for MS diagnosis.

Acknowledgements

This research was supported in part by the Intramural Research Program of the National Institute of Neurological Disorders and Stroke.

References

1. Sati P, Oh J, Constable RT, et al. The central vein sign and its clinical evaluation for the diagnosis of multiple sclerosis: a consensus statement from the North American Imaging in Multiple Sclerosis Cooperative. Nature Reviews Neurology (in press).

2. Sati P, George IC, Shea CD, et al. FLAIR*: a combined MR contrast technique for visualizing white matter lesions and parenchymal veins. Radiology 265, 926–932 (2012).

Figures

Figure 1: Representative T2*-weighted EPI images from a healthy subject brain scanned at three different magnetic field strengths (1.5T, 3T and 7T) using the segmented EPI prototype sequence.

Figure 2: Representative FLAIR image (left), T2*-weighted EPI image (middle) and combined FLAIR* image (right) obtained at 3T on a multiple sclerosis (MS) patient. Unlike standard FLAIR contrast, T2*-weighted and FLAIR* contrasts display the central vein inside MS lesions. FLAIR* contrast enables to identify MS lesions and central veins at the same time due to the combined cerebrospinal fluid suppression and sensitivity to magnetic susceptibility effects.

Figure 3: Representative T2*-weighted EPI images from a multiple sclerosis (MS) patient brain scanned at three different magnetic field strengths (1.5T, 3T and 7T). For each scan, the central vein inside a MS lesion (red chevrons) is readily identified on the three viewing planes (axial, coronal and sagittal). Note that the T2*-weighted acquisition at 1.5T and 3T were performed during the injection of gadolinium-based contrast agent (Gd+).

Proc. Intl. Soc. Mag. Reson. Med. 25 (2017)
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