Imaging Physics

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Imaging Physics

Headed by Chun Yuan, PhD, and Niranjan Balu, PhD, the Imaging Physics group develops novel high-resolution magnetic resonance imaging protocols and technology to accurately identify and characterize the underlying features of vessel clots that cause ischemic stroke and heart disease.

 

Recent Developments


Fast Isotropic 3D black blood MRI

3D Motion Sensitized Driven Equilibrium prepared Rapid Gradient Echo (3D-MERGE) allows isotropic (0.7 x 0.7 x 0.7 mm) black-blood MRI of the vessel wall within a 2 minute scan time with large coverage (upto 16 cm) of the carotid artery. 

3D MERGE

3D isotropic high resolution (0.7×0.7×0.7mm3) carotid artery image acquired with 3D MERGE sequence. Arrow on axial reformat shows a small piece of calcification. Vessel wall boundaries are clearly visible on all reformats.

References: Balu N, Yarnykh VL, Chu B, Wang J, Hatsukami T, Yuan C., Carotid plaque assessment using fast 3D isotropic resolution black-blood MRI. Magn Reson Med. 2011 Mar;65(3):627-37

 

Blood suppression for intraplaque hemorrhage imaging

Slab-selective Phase-sensitive inversion recovery improves on the MP-RAGE sequence by providing higher contrast for hemorrhage and improved blood-suppression by using a phase sensitive reconstruction.

SPI
Comparison between MP-RAGE and SPI showing improved contrast and blood suppression using SPI.

References: Wang J, Ferguson MS, Balu N, Yuan C, Hatsukami TS, Börnert P., Improved carotid intraplaque hemorrhage imaging using a slab-selective phase-sensitive inversion-recovery (SPI) sequence. Magn Reson Med. 2010 Nov;64(5):1332-40

Elimination of plaque mimicking flow artifacts

Motion Sensitized Driven Equilibrium preparation suppresses blood based on phase dispersion of magnetization among moving spins. Unlike inflow suppression and double-inversion recovery techniques that are flow dependent, MSDE can eliminate plaque mimicking artifacts in regions of complicated flow such as the carotid bifurcation.

MSDE

Flow suppression capability of different BB imaging techniques in the carotid bifurcation: (a) Inflow Suppression, (b) DIR, (c) Multi-slice DIR, and (d) MSDE. The residual flow signal is eliminated by MSDE but visible for other techniques (arrows). *, internal carotid lumen; **, external carotid lumen.

References:

  • Wang J, Yarnykh VL, Hatsukami T, Chu B, Balu N, Yuan C., Improved suppression of plaque-mimicking artifacts in black-blood carotid atherosclerosis imaging using a multislice motion-sensitized driven-equilibrium (MSDE) turbo spin-echo (TSE) sequence. Magn Reson Med. 2007 Nov;58(5):973-81.
  • Wang, J, Yarnykh, VL, Yuan, C. Enhanced image quality in black-blood MRI using the improved motion-sensitized driven-equilibrium (iMSDE) sequence. J Magn Reson Imaging 2010, 31(5):1256-63.


Quadruple Inversion-recovery black-blood imaging

Figure 1

• Quadruple Inversion-recovery (QIR)

A novel blood suppression method, which is highly insensitive to a T1 of blood and is intended specifically for black-blood contrast-enhanced cardiovascular imaging.

References: Yarnykh VL, Yuan C. T1-Insensitive flow suppression using quadruple inversion-recovery. Magn Reson Med 2002; 48: 899-905

 

Multislice double inversion recovery black-blood imaging

Figure 2

• Multi-slice Double Inversion-Recovery (DIR)

A time-efficient modification of the DIR blood suppression method can result in an up to eight-fold decrease in scan time.

References: Yarnykh VL, Yuan C. Multislice double inversion-recovery black-blood imaging with simultaneous slice reinversion. J Magn Reson Imaging 2003; 17: 478-483

 

Cross-relaxation imaging.

Figure 3

• Cross-relaxation imaging

A new parametric imaging modality that visualizes fiber tracts and quantitatively characterizes brain tissue offers promising new applications for neurological research which will focus on pathologies resulting in focal and systemic brain damage, such as multiple sclerosis, stroke, and other neurodegenerative, inflammatory, and autoimmune disorders.

References: Yarnykh VL, Yuan C. Cross-relaxation Imaging Reveals Detailed Anatomy of White Matter Fiber Tracts in the Human Brain. NeuroImage 2004; 23:409-424

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