Abnormal perinidal cerebral metabolism is associated with symptoms in brain arteriovenous malformation: New insights by a novel approach using oxygen-15 labelled tracers and PET

The mechanisms underlying neurological symptoms, including epilepsy, in unruptured brain arteriovenous malformations (bAVM) remain to be elucidated. The dual-tracer basis function method (DBFM) with single-scan dual-tracer (¹⁵O₂ and C¹⁵O₂) approach is a novel PET imaging technique that can evaluate the hemodynamics and metabolism of brain tissue adjacent to the nidus without the influence of abundant vascular radioactivity. We aimed to clarify the relationship between neurological symptoms and hemodynamic and metabolic abnormalities using the DBFM. Cerebral blood volume (CBV), cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO₂), and oxygen extraction fraction (OEF) were compared between symptomatic and asymptomatic bAVMs and before and after treatment. Among 46 patients with unruptured bAVMs who underwent DBFM, 26 cases were included. While CBV and OEF increased in the perinidus (p < 0.01), CBF and CMRO₂ decreased (p < 0.01). Symptoms were significantly associated with higher OEF (symptomatic vs. asymptomatic, ratio of perinidal to contralateral, n = 13 vs. n = 13, 1.07 ± 0.030 vs. 1.01 ± 0.080, p = 0.017). All elevated OEFs in symptomatic bAVMs with therapeutic symptom resolved in post-therapeutic PET imaging. DBFM revealed a higher OEF was associated with symptomatic bAVM. The DBFM potentially aids in predicting post-therapeutic symptom improvement.