[Utility of sampling perfection with application optimized contrasts using different flip angle evolutions method in magnetic resonance imaging of carotid artery plaque]

Carotid and aortic plaque imaging using 3D gradient-echo imaging and the three-point Dixon method with improved motion-sensitized driven-equilibrium (iMSDE)

BACKGROUND

We devised a method that combines the 3D-Dixon-gradientecho (GRE) method with an improved motion-sensitized driven-equilibrium (iMSDE) to suppress blood flow signals.

PURPOSE

The purpose of this study was to evaluate the effectiveness of the new method we developed plaque imaging method (3D-Dixon-GRE with the iMSDE method).

STUDY TYPE

Retrospective cohort.

POPULATION

Thirty-nine patients who underwent cervical plaque imaging.

FIELD STRENGTH/SEQUENCE

3.0 T/3D-GRE.

ASSESSMENT

Signal intensities of the common carotid artery, aorta, plaque, muscle, and subcutaneous fat were measured through the VISTA and the 3D-Dixon-GRE with iMSDE methods, and each contrast was calculated.

STATISTICAL TEST

Used the Mann Whitney U test. P-values below 0.05 were considered statistically significant.

RESULTS

Plaque and muscle contrast estimated through the VISTA method and 3D-Dixon-GRE with iMSDE method was 1.60 ± 0.96 and 2.04 ± 1.06, respectively, (P < 0.05). The contrast between the flow (common carotid artery and Aorta) and muscle according to the VISTA method and 3D-Dixon-GRE with iMSDE method was 0.24 ± 0.11 and 0.40 ± 0.12, respectively (P < 0.001). Finally, the mean contrast for subcutaneous fat and muscle at six locations was 3.05 ± 1.25 and 0.81 ± 0.23 for the VISTA method and 3D-Dixon-GRE with the iMSDE method, respectively (P < 0.001).

DATA CONCLUSION

Compared to the conventional method (VISTA), the 3D-Dixon-GRE with iMSDE method is preferable in relation to the fat suppression effect, but it is disadvantageous regarding blood flow signal suppression. Therefore, the 3D-Dixon-GRE with the iMSDE method could be considered useful for plaque imaging.

[Evaluation of Refocus Flip Angle for Three-dimensional Proton Density-weighted Turbo Spin-echo Imaging in Cerebrovascular Black Blood MRA and Comparison with Three-dimensional Time-of-flight MRA]

The three-dimensional time-of-flight (3D-TOF), which is currently the most common acquisition technique of intracranial magnetic resonance angiography (MRA), may result in poor branch visualization due to reduced blood flow velocity. Proton density-weighted volume isotropic turbo spin-echo acquisition (PDVISTA) is less susceptible to these factors and has been reported to be useful in assessing cerebral vasospasm after subarachnoid hemorrhage. In this study, we investigated the effect of refocus flip angle (RFA) for PDVISTA on the contrast between blood vessels and background brain tissue using flow velocity phantom and clinical images, assuming the usefulness of PDVISTA in daily clinical practice. The phantom experiments showed that the contrast ratio significantly improved with decreasing RFA; however, considering the signal-to-noise ratio, RFA 80° was determined as optimal for clinical use. Visual assessment was performed on PDVISTA (RFA 80°) and conventional 3D-TOF MRA clinical images, which suggested the superiority of PDVISTA over 3D-TOF in the delineation of peripheral branches of cerebral vessels. The results suggest that PDVISTA is useful not only for subarachnoid hemorrhage patients but also in daily clinical practice.