Middle meningeal artery (MMA) particle embolization is apromising treatment of chronic subdural hematomas (CSDH). The main purpose of this study is to measure MMA proximal caliber and assess the visibility of the two main MMA branches as asurrogate for long-term distal arterial patency following MMA CSDH embolization with trisacryl gelatine microspheres (TAGM). This is asingle-center retrospective study. All patients having undergone MMA TAGM only embolization for CSDH treatment between 15 March 2018 and 6 June 2020 with an interpretable follow-up magnetic resonance imaging (MRI) examination and no confounding factors were included. Patients were compared with controls matched for age, sex and MRI machine. Two independent readers analyzed the MRI images. In this study, 30 patients having undergone embolization procedures using TAGM of 36MMAs were included. The follow-up MRI scans were performed after amean delay of 14.8 ± 7.1months (range 4.9-29.4months). The mean diameter of TAGM embolized MMAs (1 mm; 95% confidence interval, CI 0.9-1.1) was significantly smaller than the mean diameter of paired control MMAs (1.3 mm; 95% CI 1.3-1.4) (p < 0.001). The mean proximal diameter of the embolized MMAs (0.9 mm; 95% CI 0.7-1.1) was significantly smaller than the mean diameter of the contralateral MMAs in the same patients (1.4 mm; 95% CI 1.3-1.6)(p < 0.001). Long-term follow-up MRI demonstrated asignificant impact of TAGM embolization on MMA proximal caliber as well as on the visibility of the two main MMA branches. All comparisons indicated that there was aprobable lasting impact of embolization on the patency of distal branches.