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Dark Blood Contrast-Enhanced Brain MRI Using Echo-uT1RESS
Robert R Edelman1,2, Nondas Leloudas1, William J Ankenbrandt1
1Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA.
Background:
The widely used magnetization-prepared rapid gradient-echo (MPRAGE) sequence makes enhancing lesions and blood vessels appear bright after gadolinium administration. However, dark blood imaging using T1-weighted Sampling Perfection with Application optimized Contrast using different flip angle Evolution (T1 SPACE) can be advantageous since it improves the conspicuity of small metastases and leptomeningeal disease. As a potential alternative to T1 SPACE, we evaluated a new dark blood sequence called echo-uT1RESS (unbalanced T1 Relaxation-Enhanced Steady-State).
Purpose:
We compared the performance of echo-uT1RESS with Dixon fid-uT1RESS, MPRAGE, and T1 SPACE.
Study Type:
Retrospective, IRB approved.
Subjects/Phantom:
Phantom to assess flow properties of echo-uT1RESS. Twenty-one patients (14 female, age range 35-82 years) with primary and secondary brain tumors.
Field Strength/Sequences:
3 Tesla/MPRAGE, T1 SPACE, Dixon fid-uT1RESS, echo-uT1RESS.
Assessment:
Flow phantom signal vs. velocity as a function of flip angle and sequence. Qualitative image assessment on 4-point scale. Quantitative evaluation of tumor-to-brain contrast, apparent contrast-to-noise ratio (aCNR), and vessel-to-brain aCNR.
Statistical Tests:
Friedman and Mann-Whitney U tests. A P value <0.05 was considered statistically significant.
Results:
In the phantom, echo-uT1RESS showed greater flow-dependent signal loss than fid-uT1RESS. In patients, blood vessels appeared bright with MPRAGE, gray with fid-uT1RESS, and dark with T1 SPACE and echo-uT1RESS. For MPRAGE, Dixon fid-uT1RESS, echo-uT1RESS, and T1 SPACE, respective tumor-to-brain contrast values were 0.6 ± 0.3, 1.3 ± 0.5, 1.0 ± 0.4, and 0.6 ± 0.4, while normalized aCNR values were 68.9 ± 50.9, 128.4 ± 59.2, 74.2 ± 42.1, and 99.4 ± 73.9.
Data Conclusion:
Volumetric dark blood contrast-enhanced brain MRI is feasible using echo-uT1RESS. The dark blood effect was improved vs. fid-uT1RESS, while both uT1RESS versions provided better tumor-to-brain contrast than MPRAGE. Whereas T1 SPACE provided better tumor aSNR, echo-uT1RESS provided better Weber contrast, lesion sharpness and a more consistent dark blood effect.
Evidence Level:
3 TECHNICAL EFFICACY: Stage 1.
