Longitudinal Imaging of Tumor Volume, Diffusivity, and Perfusion After Preoperative Endovascular Embolization in Supratentorial Hemispheric Meningiomas

Abstract

Objective: To describe longitudinal image changes in supratentorial hemispheric meningiomas based on magnetic resonance imaging after preoperative embolization using calibrated microspheres.

Methods: A total of 14 patients with symptomatic supratentorial meningiomas were included in a prospective, mono-centric, mono-arm study. Magnetic resonance imaging changes on diffusion-weighted imaging, dynamic contrast susceptibility-perfusion-weighted imaging, susceptibility-weighted imaging, and magnetization-prepared rapid acquisition gradient-echo sequence T1-weighted postcontrast sequences 6 and 48 hours after embolization were evaluated and correlated with angiographic and clinical data.

Results: The mean age of the patients was 63 ± 12.7 years with an equal female/male ratio. Twelve meningiomas were World Health Organization grade I and II tumors. After embolization, baseline apparent diffusion coefficient (901 ± 166 mm²/s) decreased significantly within 6 hours (696 ± 115 mm2/s, P = 0.0008) as well within 48 hours (752 ± 134 mm²/s; P = 0.0147). Baseline mean ratio of relative cerebral blood volume (rCBV)_tumor/rCBV_{white matter} (3.67 ± 1.83) and relative cerebral blood flow (rCBF)_tumor/rCBF_{white matter} (2.89 ± 1.57) significantly decreased after embolization within 6 hours (rCBV_tumor/rCBV_{white matter} of 1.45 ± 0.9; P = 0.0007, rCBF of 1.16 ± 0.68; P = 0.0029) and 48 hours (rCBV of 1.50 ± 1.07; P = 0.0009, rCBF_tumor/rCBF_{white matter} of 1.19 ± 0.8; P = 0.003). The viable enhanced baseline mean tumor volume (54.3 ± 34.9 mm³) was sustainably and significantly diminished within 6 hours (26.6 ± 20.8 mm³; P = 0.02) and 48 hours (29.7 ± 22.5 mm³; P = 0.035) after embolization. There was a good correlation between angiographic devascularization rate and the embolized tumor volume at 6 hours (r = 0.7; P = 0.03) and 48 hours (r = 0.78; P = 0.041).

Conclusions: Preoperative meningioma embolization with calibrated microspheres is safe and effectively induces a significant and sustainable tissue transformation over 48 hours.

Keywords: Embolization; MRI; Meningioma; Microspheres; Tumor.