Simultaneous CBF and CMRGlu as imaging biomarkers for differential treatments in ICA/MCA steno-occlusive disease: a retrospective study

BACKGROUND Steno-occlusive diseases of the internal carotid artery (ICA) or middle cerebral artery (MCA) can lead to hemodynamic impairment, yet conventional imaging often fails to reflect metabolic dysfunction. Integrated positron emission tomography and magnetic resonance imaging (PET/MRI) allows simultaneous assessment of cerebral blood flow (CBF) and glucose metabolism. This study compared baseline perfusion and metabolic characteristics between patients receiving medical therapy or extracranial–intracranial (EC-IC) bypass surgery. METHODS This retrospective study enrolled 34 patients with unilateral ICA/MCA stenosis or occlusion confirmed by digital subtraction angiography. All patients underwent 18 F-FDG PET/MRI before treatment. Glucose metabolism was quantified using the cerebral metabolic rate of glucose (CMRGlu) from dynamic PET and the standard uptake value ratio (SUVR) from static PET. CBF was measured using three-dimensional arterial spin labeling with post-labeling delays of 2.0 and 2.5 seconds. Perfusion and metabolic parameters were compared across vascular territories. RESULTS Baseline clinical characteristics and long-term outcomes did not differ between groups (all P >0.05). Cerebral blood flow was similar across all arterial territories and post-labeling delays, with no hemispheric asymmetry detected (all P >0.05). In contrast, glucose metabolism was significantly lower in the surgical group, with reduced CMRGlu in the ischemic middle cerebral artery (23.58±7.46 vs 18.82±5.04μmol/100g -1 /min -1 , P =0.037) and anterior cerebral artery territories (26.37±8.76 vs 20.71±5.78μmol/100g -1 /min -1 , P =0.034). No differences were observed in the posterior cerebral artery or in SUVR across all regions (all P >0.05). CONCLUSIONS Despite similar perfusion profiles, the surgical group demonstrated lower glucose metabolism, suggesting that metabolic imaging may aid in identifying patients who could benefit from revascularization.