Perfusion Imaging’s Role in Endovascular Therapy Outcomes for Posterior Cerebral Artery Stroke

Highlight

1. Larger baseline hypoperfusion volume correlates with lower odds of excellent 90-day outcomes in isolated posterior cerebral artery occlusion (iPCAO).
2. Perfusion imaging parameters independently provide prognostic information but do not predict which patients benefit most from endovascular therapy (EVT).
3. Increasing infarct core volume is linked to worse functional outcomes and higher mortality when treated with EVT compared to medical management.
4. Larger hypoperfusion volumes associate with an increased risk of symptomatic intracranial hemorrhage after EVT.

Study Background

Isolated posterior cerebral artery occlusion (iPCAO) is a form of ischemic stroke involving the territory supplied by the posterior cerebral artery. Despite its clinical relevance, management strategies, particularly the role of endovascular therapy (EVT), remain less defined compared to anterior circulation strokes. Perfusion imaging—such as computed tomography (CT) or magnetic resonance imaging (MRI) perfusion scans—offers parameters like hypoperfusion volume, infarct core volume, and mismatch ratio that may depict the extent of ischemic penumbra and infarcted tissue. Understanding whether these parameters can guide treatment decisions, predict clinical outcomes, or indicate safety risks of EVT in iPCAO is critical for optimizing care and improving prognostication.

Study Design

This investigation represents a prespecified secondary analysis of the international, multicenter PLATO (Posterior Cerebral Artery Occlusion) registry encompassing 35 centers across 10 countries between 2015 and 2025. The analysis included 443 adult patients with unilateral iPCAO and baseline perfusion imaging allowing reconstruction of perfusion parameters. Patients’ median age was 74 years, and 41.8% were female.

Primary outcome was defined as an excellent clinical state measured by a modified Rankin Scale (mRS) score of 0–1 at 90 days post-stroke.

Perfusion parameters assessed included hypoperfusion volume, infarct core volume, and mismatch ratio. Multivariable mixed-effects regression models were constructed with center as a random effect, adjusting for covariates: age, sex, treatment year, prestroke mRS, baseline National Institutes of Health Stroke Scale (NIHSS) score, diabetes status, stroke cause, posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS), occlusion site, intravenous thrombolysis administration, and time from stroke onset to hospital arrival.

To explore whether perfusion parameters modulate EVT effects on outcomes, treatment-by-perfusion interaction analyses were conducted using inverse probability of treatment weighting-adjusted models, with findings expressed as ratios of odds ratios (ORs).

Key Findings

Of the 1811 patients with iPCAO in the registry, 443 met inclusion criteria for this perfusion-imaging-based study. Major results include:

1. Prognostic impact of hypoperfusion volume: A larger baseline hypoperfusion volume was independently associated with a decreased likelihood of excellent 90-day outcome (adjusted OR, 0.72; 95% CI, 0.58–0.89 per 1-unit increase in natural logarithm-transformed volume). This suggests that greater ischemic tissue jeopardy predicts poorer recovery.

2. EVT benefit and interaction with perfusion parameters: No significant interaction was observed between perfusion parameters and EVT for the primary dichotomized outcome of excellent 90-day mRS, indicating that these imaging metrics do not identify patients who derive differential benefit from EVT over medical therapy.

3. Infarct core volume and worse clinical outcomes with EVT: Increasing core infarct volume correlated with less favorable shift in the mRS distribution (ratio of OR, 0.66; 95% CI, 0.48–0.90; Pinteraction=0.009) and higher mortality (ratio of OR, 1.82; 95% CI, 1.10–3.03; Pinteraction=0.021) with EVT compared to medical management. This indicates larger core infarction may elevate risk or reduce benefit from EVT.

4. Safety concerns – symptomatic intracranial hemorrhage (sICH): Increasing hypoperfusion volume was associated with a higher risk of sICH following EVT (ratio of OR, 10.15; 95% CI, 1.06–96.93; Pinteraction=0.044). This finding highlights a potential safety signal linked to extensive perfusion deficits.

These results underscore the independent prognostic relevance of perfusion characteristics but suggest limited utility in guiding EVT selection or predicting its clinical benefit in iPCAO patients.

Expert Commentary

The PLATO registry secondary analysis by Diel et al. significantly advances understanding of perfusion imaging in posterior circulation strokes, a historically under-researched area compared to anterior circulation events. The robust multicenter design and comprehensive adjustment for confounders strengthen the validity of findings.

The dissociation between perfusion parameters predicting outcome but not treatment benefit is important clinically; it cautions against overreliance on such measures alone to select patients for EVT. Larger infarct core volumes correlating with worse functional outcomes and higher mortality align with known mechanistic risks whereby irreversible ischemic damage limits recovery potential and increases reperfusion injury risk.

The association of hypoperfusion volume with sICH suggests that extensive ischemic burden may predispose to hemorrhagic transformation when EVT is attempted, emphasizing the need for careful risk stratification.

Limitations include observational design and possible residual confounding despite adjustment; also, the study did not randomize EVT versus medical management. Generalizability to centers without advanced perfusion imaging remains uncertain. Nonetheless, the study sets the stage for future randomized trials focusing on imaging-based selection strategies specific to posterior circulation strokes.

Conclusion

Perfusion imaging parameters—hypoperfusion volume, infarct core, and mismatch ratios—offer valuable prognostic information in isolated posterior cerebral artery occlusion. However, these parameters do not robustly modify the benefits of endovascular therapy and may instead identify patients at increased procedural risk, notably due to hemorrhagic complications. Clinicians should utilize perfusion imaging as an adjunct in prognostication but be cautious in using these metrics alone to guide EVT decisions in iPCAO.

Further prospective, randomized investigations are warranted to refine patient selection criteria and optimize therapeutic strategies in posterior circulation stroke.

Funding and Registration

The study was conducted within the PLATO registry framework, registered at https://osf.io/62mwt (Unique identifier: XXXX), supported by international collaborating institutions. Specific funding sources were not detailed in the original report.

References

1. Diel NJ, Strambo D, Abdalkader M, et al. Role of Perfusion Parameters on Outcomes and Safety of Endovascular Therapy in Posterior Cerebral Artery Stroke. Stroke. 2026 Jul 9. PMID: 42422957.
2. Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomized trials. Lancet. 2016;387(10029):1723-1731.
3. Powers WJ, Rabinstein AA, Ackerson T, et al. 2018 Guidelines for the early management of patients with acute ischemic stroke: A guideline from the American Heart Association/American Stroke Association. Stroke. 2018;49(3):e46-e110.
4. Mokin M, Dumont TM, Walker G, et al. Trends in utilization and outcomes of endovascular therapy for posterior circulation stroke. Stroke. 2016;47(3):1130-1136.