Correlation between fractional flow and magnetic resonance perfusion in patients with intracranial artery stenosis in the anterior circulation.

BACKGROUND

The value of hemodynamics in intracranial atherosclerotic stenosis (ICAS) patients has not been fully studied. The purpose of this study was to analyze the correlation between fractional flow (FF) and hypoperfusion in patients with ICAS of the anterior circulation, and compare the performance differences between FF and diameter stenosis (DS) in distinguishing hypoperfusion.

METHODS

This study included patients with anterior circulation artery stenosis. The determination of cerebral perfusion stages and the calculation of perfusion parameters were based on the magnetic resonance imaging (MRI) perfusion images. The patients were divided into a normal perfusion group and a hypoperfusion group (stages I and II). DS and FF values were calculated on the basis of digital subtraction angiography images.

RESULTS

We analyzed 58 patients. FF was negatively correlated with relative time to peak (r=-0.41, P=0.002) and relative mean transit time (r=-0.27, P=0.037). In groups with a larger time to maximum tissue residue function, FF had a lower distribution interval. FF was significantly different between normal perfusion patients and hypoperfusion patients (0.71±0.17 vs. 0.52±0.18, P<0.05), while DS was not (0.66±0.17 vs. 0.54±0.13, P=0.087). Multivariate analysis indicated FF (odds ratio, 0.08; 95% confidence interval: 0.01-0.80) was the only independent factor. Receiver operating characteristic analysis revealed the area under the curve for differentiating hypoperfusion from normal perfusion. The areas under the curve were 0.739 (0.597-0.850) for DS and 0.772 (0.632-0.876) for FF. The accuracy, sensitivity and specificity at the optimal cutoff (FF=0.61) were 76.6% (58.8-92.1%), 76.4% (56.5-93.3%) and 78.7% (58.3-95.8%), respectively.

CONCLUSIONS

There is a correlation between MRI perfusion and FF in patients with anterior circulation ICAS. A low FF may indicate a higher time to maximum tissue residue function and a poorer hypoperfusion stage. FF provides hemodynamic information that is distinct from and complementary to the anatomical assessment of DS. The ability to compute FF intraoperatively could, in the future, provide real-time feedback on physiological improvement following revascularization.