Three-dimensional multicontrast blood imaging with a single acquisition: Simultaneous non-contrast-enhanced MRA and vessel wall imaging in the thoracic aorta
Yoshihiko Tachikawa, Hiroshi Hamano, Hikaru Yoshikai, Kento Ikeda, Yasunori Maki, Kazuhide Hirata,Yukihiko Takahashi, Kunishige Matake
Abstract
Purpose
To evaluate MRA and vessel wall imaging (VWI) image quality in the thoracic aorta using a novel method named BRIDGE (bright and dark blood images with multishot gradient-echo EPI).
Methods
The BRIDGE method consists of 3D multishot gradient-echo EPI acquisition using pulse gating, navigator gating, and magnetization preparation with a T2-preparation pulse and a nonselective inversion-recovery pulse. The BRIDGE and conventional methods (noncontrast MRA based on 3D turbo-field-echo [TFE] and VWI based on 3D turbo spin echo with variable refocusing flip angle [VRFA-TSE]) were performed in 10 healthy volunteers and 10 patients. The SNR, contrast-to-noise ratio (CNR), and sharpness in the thoracic aorta were compared for MRA evaluation. The values of SNRlumen, SNRwall, CNRwall−lumen, contrast ratio (CR)lumen−muscle, coefficient of variation, sharpness, lumen area, and wall area in the thoracic aorta were compared for VWI evaluation. Two radiologists independently performed qualitative image-analysis assessments.
Results
When MRA and VWI were acquired, the acquisition time was 26.6% to 27.8% shorter with BRIDGE than the conventional method. In the MRA evaluation, BRIDGE and TFE methods were comparable. In the VWI evaluation, BRIDGE was superior to the VRFA-TSE method in blood suppression and evaluation of the ascending aorta. Because the blood signal suppression of BRIDGE is based on the T1 value of blood, the blood signal can be suppressed more uniformly than with the VRFA-TSE method, regardless of age, blood flow velocity, or vascular anatomy.
Conclusion
The BRIDGE method can provide both MRA, to assess vascular anatomy and luminal changes, and VWI, to assess the vessel wall and detect vulnerable plaques, in a single scan.