Elsevier

Journal of Neuroradiology

Volume 40, Issue 4, October 2013, Pages 303-306
Journal of Neuroradiology

Technical note
Evaluation of tumor blood flow after feeder embolization in meningiomas by arterial spin-labeling perfusion magnetic resonance imaging

https://doi.org/10.1016/j.neurad.2013.04.005Get rights and content

Summary

Preoperative embolization changes the amount of blood flow and pattern of flow distribution in meningioma. Tumor blood flow was investigated in eight meningioma patients before and after embolization using arterial spin-labeling (ASL) perfusion imaging. Although blood flow was significantly reduced in the whole tumor after embolization, changes in flow distribution patterns varied from one case to another. The findings suggest that evaluation of post-embolization tumor blood flow by ASL perfusion imaging would be useful in the surgical planning of meningioma.

Introduction

Preoperative embolization of meningioma facilitates surgical resection by decreasing intraoperative bleeding and softening tumors. The most commonly accepted indications for preoperative embolization include large and highly vascular convexity meningiomas supplied primarily by the external carotid artery (ECA) [1]. However, there is no standard method for evaluating how much the tumor blood flow is decreased by embolization before surgical resection. In addition, for those tumors supplied mainly by the internal carotid artery (ICA), embolization of the ECA may increase surgical risks [2], [3]. The potential explanation of this is that tumor blood flow and flow distribution patterns are dynamically changed by embolization of one or several of the multiple feeders. This means that preoperative evaluation of flow diversion after embolization is important. Arterial spin-labeling (ASL) perfusion imaging has already been widely used clinically for measuring blood flow in both physiological and pathological states such as brain tumors [4], [5], [6], [7], [8], [9]. In the present study, tumor blood flow in meningioma was measured by ASL perfusion imaging before and after embolization to evaluate changes in blood flow and distribution patterns.

Section snippets

Patients

This study had the approval of our institutional review board, and all participants gave their written informed consent prior to starting the study. Between April 2011 and March 2012, eight patients with meningioma (two men and six women) underwent embolization at our institution (Table 1). Average age of the patients was 56 years (range: 25–76 years). Tumor locations were convexity (two cases), parasagittal (two cases), falx (one case), sphenoid ridge (one case), tentorial (one case) and

Results

Digital subtraction angiography after embolization demonstrated the disappearance of staining by embolized feeders (data not shown). The pre-embolization T/N ratio was 2.96 ± 0.69 (range: 1.39–7.21) and the post-embolization T/N ratio was 1.98 ± 0.47 (range: 0.43–4.66; Table 1 and Fig. 1). As shown in Fig. 1, the post-embolization T/N ratio decreased in most cases and the difference was statistically significant (P < 0.05 by paired t test). However, the degree and pattern of decrement in tumor blood

Discussion

The devascularization of tumors after embolization is usually evaluated by angiography, contrast-enhanced computed tomography (CT) and MRI. Angiography directly demonstrates the disappearance of tumor staining, while focal defects of enhancement on contrast-enhanced CT and MRI suggest tumor infarction (Fig. 4, lower left). However, these imaging techniques fail to substantially show tumor perfusion status. Dynamic susceptibility contrast (DSC) perfusion imaging is a qualitative MRI perfusion

Disclosure of interest

The authors declare that they have no conflicts of interest concerning this article.

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    Martin et al.31 showed that magnetic resonance perfusion imaging can delineate the distribution territory of vessels; moreover, changes in tumor vasculature could be detected after embolization. Likewise, Kawaji et al.32 reported that arterial spin labeling can be used to evaluate tumor blood flow after embolization. Our study also noted that larger tumor volume and male gender were significantly correlated with higher EBL.

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    Recent studies applying ASL for brain tumors have gradually clarified its clinical relevance in evaluation of therapeutic efficacy.14,16,17 Kawaji et al.16 concluded that the pattern of decrement measured by ASL after feeder embolization for meningiomas varied case by case. Because the lesion's change from high intensity to isointensity is assumed to correspond to the area fed by the ECA, and high-resolution anatomic images and blood flow images can be obtained in the same session, this revealed that CBF maps depicted the location where hemodynamic changes occurred inside the tumors after embolization.

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