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Perfusion Collateral Index versus Hypoperfusion Intensity Ratio in Assessment of Collaterals in Patients with Acute
Brian Tsui1, Iris E Chen1, May Nour1,2
1From the Department of Radiological Sciences (B.T., I.E.C., M.N., S.K., E.T., J.Q., C.A., S.T., N.S., J.P.V., R.J., G.D., K.N.), David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California.
Insights
The perfusion collateral index is a better measure for assessing collateral status in acute ischemic stroke patients than the hypoperfusion intensity ratio. It predicts outcomes like infarct growth and functional independence more effectively.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Collateral circulation is crucial in acute ischemic stroke (AIS).
- Perfusion-based indices like the perfusion collateral index (PCI) and hypoperfusion intensity ratio (HIR) show promise for assessing collaterals.
- Comparing their diagnostic performance against established methods is essential.
Purpose of the Study:
- To compare the diagnostic performance of PCI and HIR.
- To evaluate their accuracy in assessing collateral status against digital subtraction angiography (DSA).
- To determine their association with key outcome measures: final infarct volume, infarct growth, and functional independence.
Main Methods:
- Included 98 AIS patients with anterior circulation proximal arterial occlusion undergoing endovascular thrombectomy.
- Calculated PCI and HIR using pre-treatment MR perfusion imaging.
- Dichotomized angiographic collaterals from DSA into sufficient (ASITN 3-4) vs. insufficient (ASITN 0-2).
Main Results:
- PCI values were significantly higher in patients with sufficient angiographic collaterals (P < .001), unlike HIR (P = .46).
- A PCI of ≥ 62 was associated with good functional outcome (72% vs. 31%, P = .003), while HIR ≤ 0.4 showed no significant difference (69% vs. 56%, P = .52).
- Both indices predicted final infarct volume, but only PCI significantly correlated with infarct growth (P = .03).
Conclusions:
- The perfusion collateral index demonstrates superior performance compared to the hypoperfusion intensity ratio.
- PCI is more effective in assessing collateral status, predicting infarct growth, and determining functional outcomes in AIS patients.
Background And Purpose:
Perfusion-based collateral indices such as the perfusion collateral index and the hypoperfusion intensity ratio have shown promise in the assessment of collaterals in patients with acute ischemic stroke. We aimed to compare the diagnostic performance of the perfusion collateral index and the hypoperfusion intensity ratio in collateral assessment compared with angiographic collaterals and outcome measures, including final infarct volume, infarct growth, and functional independence.
Materials And Methods:
Consecutive patients with acute ischemic stroke with anterior circulation proximal arterial occlusion who underwent endovascular thrombectomy and had pre- and posttreatment MRI were included. Using pretreatment MR perfusion, we calculated the perfusion collateral index and the hypoperfusion intensity ratio for each patient. The angiographic collaterals obtained from DSA were dichotomized to sufficient (American Society of Interventional and Therapeutic Neuroradiology [ASITN] scale 3-4) versus insufficient (ASITN scale 0-2). The association of collateral status determined by the perfusion collateral index and the hypoperfusion intensity ratio was assessed against angiographic collaterals and outcome measures.
Results:
A total of 98 patients met the inclusion criteria. Perfusion collateral index values were significantly higher in patients with sufficient angiographic collaterals (P < .001), while there was no significant (P = .46) difference in hypoperfusion intensity ratio values. Among patients with good (mRS 0-2) versus poor (mRS 3-6) functional outcome, the perfusion collateral index of ≥ 62 was present in 72% versus 31% (P = .003), while the hypoperfusion intensity ratio of ≤0.4 was present in 69% versus 56% (P = .52). The perfusion collateral index and the hypoperfusion intensity ratio were both significantly predictive of final infarct volume, but only the perfusion collateral index was significantly (P = .03) associated with infarct growth.
Conclusions:
Results show that the perfusion collateral index outperforms the hypoperfusion intensity ratio in the assessment of collateral status, infarct growth, and determination of functional outcomes.
