Differentiation Between the Low and High Trans‐Stenotic Pressure Gradient in Patients With Idiopathic Intracranial Hypertension Using 4D Flow MRI‐Derived Hemodynamic Parameters

Background Trans‐stenotic pressure gradient (TPG) measurement is essential for idiopathic intracranial hypertension (IIH) patients with transverse sinus (TS) stenosis. Four‐D flow MRI may provide a noninvasive imaging method for differentiation of IIH patients with different TPG. Purpose To investigate the associations between 4D flow parameters and TPG, and to evaluate the diagnostic performance of 4D flow parameters in differentiating patients with high TPG (Group HP ) from low TPG (Group LP ). Study type Prospective. Population 31 IIH patients with TS stenosis (age, 38 ± 12 years; 23 females) and 5 healthy volunteers (age, 25 ± 1 years; 2 females). Field Strength/Sequence 3T, 3D phase contrast MR venography, and gradient recalled echo 4D flow sequences. Assessment Scan‐rescan reproducibility of 4D flow parameters were performed. The correlation between TPG and flow parameters was analyzed. The netflow and velocity difference between inflow plane, outflow plane, and the stenosis plane were calculated and compared between Group HP and Group LP . Statistical Tests Pearson's correlation or Spearman's rank correlation coefficient, Independent samples t‐test or Wilcoxon rank‐sum test, Intra‐class correlation coefficient (ICC), Bland–Altman analyses, Receiver operating characteristic curves. A P value <0.05 was considered significant. Results Significant correlations were found between TPG and netflow parameters including F avg,out‐s , F avg,in‐s , F max,out‐s , and F max,in‐s ( r = 0.525–0.565). Significant differences were found in F avg,out‐s , F max,out‐s , F avg,in‐s , and F max,in‐s between Group HP and Group LP . Using the cut‐off value of 2.19 mL/sec, the F avg,out‐s showed good estimate performance in distinguishing Group HP from Group LP (AUC = 0.856). The ICC (ranged 0.905–0.948) and Bland–Altman plots indicated good scan‐rescan reproducibility. Data Conclusions 4D flow MRI derived flow parameters showed good correlations with TPG in IIH patients with TS stenosis. Netflow difference between outflow and stenosis location at TS shows the good performance in differentiating Group HP and Group LP cases. Level of Evidence 2 Technical Efficacy Stage 2