Intracranial Blood Flow Quantification by Accelerated Dual‐venc 4D Flow MRI: Comparison With Transcranial Doppler Ultrasound

BACKGROUND: Dual‐venc 4D flow MRI, recently introduced for the assessment of intracranial hemodynamics, may provide a promising complementary approach to well‐established tools such as transcranial Doppler ultrasound (TCD) and overcome some of their disadvantages. However, data comparing intracranial flow measures from dual‐venc 4D flow MRI and TCD are lacking. PURPOSE: To compare cerebral blood flow velocity measures derived from dual‐venc 4D flow MRI and TCD. STUDY TYPE: Prospective cohort. SUBJECTS: A total of 25 healthy participants (56 ± 4 years old, 44% female). FIELD STRENGTH/SEQUENCE: A 3 T/dual‐venc 4D flow MRI using a time‐resolved three‐dimensional phase‐contrast sequence with three‐dimensional velocity encoding. ASSESSMENT: Peak velocity measurements in bilateral middle cerebral arteries (MCA) were quantified from dual‐venc 4D flow MRI and TCD. The MRI data were quantified by two independent observers (S.M and Y.M.) and TCD was performed by a trained technician (A.L.M.). We assessed the agreement between 4D flow MRI and TCD measures, and the interobserver agreement of 4D flow MRI measurements. STATISTICAL TESTS: Peak velocity from MRI and TCD was compared using Bland–Altman analysis and coefficient of variance. Intraclass correlation coefficient (ICC) was used to assess MRI interobserver agreement. A P value < 0.05 was considered statistically significant. RESULTS: There was excellent interobserver agreement in dual‐venc 4D flow MRI‐based measurements of peak velocity in bilateral MCA (ICC = 0.97 and 0.96 for the left and right MCA, respectively). Dual‐venc 4D flow MRI significantly underestimated peak velocity in the left and right MCA compared to TCD (bias = 0.13 [0.59, −0.33] m/sec and 0.15 [0.47, −0.17] m/sec, respectively). The coefficient of variance between dual‐venc 4D flow MRI and TCD measurements was 26% for the left MCA and 22% for the right MCA. DATA CONCLUSION: There was excellent interobserver agreement for the assessment of MCA peak velocity using dual‐venc 4D flow MRI, and ≤20% under‐estimation compared with TCD. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2