Dark Blood Contrast‐Enhanced Brain MRI Using Echo‐uT1RESS

Abstract

BackgroundThe 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).PurposeWe compared the performance of echo‐uT1RESS with Dixon fid‐uT1RESS, MPRAGE, and T1 SPACE.Study TypeRetrospective, IRB approved.Subjects/PhantomPhantom 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/Sequences3 Tesla/MPRAGE, T1 SPACE, Dixon fid‐uT1RESS, echo‐uT1RESS.AssessmentFlow 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 TestsFriedman and Mann–Whitney U tests. A P value <0.05 was considered statistically significant.ResultsIn 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 ConclusionVolumetric 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 Level3Technical EfficacyStage 1