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BACKGROUND AND PURPOSE: Embolization of meningiomas has emerged as a preoperative adjuvant therapy that has proved effective in mitigating blood loss during surgical resection. Arterial supply to these tumors is typically identified by diffuse areas of parenchymal staining after selective x-ray angiograms. We investigate the benefits that selective injection of MR contrast may have in identifying vascular territories and determining the effects of embolization therapy.MATERIALS AND METHODS: Selective intra-arterial (IA) injection of dilute MR contrast media was used to assess the vascular distribution territories of meningeal tumors before and after embolization therapy. Regions of the tumor that experienced loss of signal intensity after localized contrast injections into the external and common carotid as well as vertebral arteries were used to quantify the specific vessel's volume of distribution. Assessments were made before and after embolization to reveal changes in the vascular supply of the tumor. MR findings were compared with radiographic evaluation of tumor vascular supply on the basis of conventional x-ray angiography.RESULTS: MR proved to be an excellent means to assess tissue fed by selected arteries and clearly demonstrated the treated and untreated portions of the neoplasm after therapy. In some instances, MR revealed postembolization residual enhancement of the tumor that was difficult to appreciate on x-ray angiograms. Very low contrast dose was necessary, which made repeated assessment during therapy practical.CONCLUSION: MR perfusion imaging with selective IA injection of dilute contrast can reveal the distribution territory of vessels. Changes in tumor vasculature could be detected after embolization, which reveal the volumetric fraction of the tumor affected by the therapy.

Introduction Magnetic resonance imaging (MRI) is most sensitive and specific for characterizing venous malformations (VMs). VMs typically demonstrate central enhancement on delayed-contrast imaging. Fluid-fluid levels (FFLs) are uncommon in VMs and common in lymphatic malformations (LMs). Technology has advanced since the initial description of these findings. Rates of detection of these MRI findings in VMs may have changed as MRI technology and techniques have evolved. Methods and methods A prospectively maintained database from a multidisciplinary vascular anomalies clinic was reviewed to identify patients with final diagnosis of VM or LM. Patients with reviewable contrast-enhanced MRIs were selected, reviewing the oldest MRI studies in the database against the newest MRI studies to identify equal numbers of patients from the temporal extremes. Imaging was reviewed to assess for presence of FFLs. Enhancement was quantified by measuring signal in the same location of the lesion both on pre- and postcontrast sequences Results Forty patients were identified for analysis. Twenty studies with sufficient archived imaging for review were performed between 1995 and 2006; 20 such studies were performed between 2011 and 2012. The new imaging cohort had higher rates of FFL visualization (p = 0.001). Correlation was found between time to imaging following contrast and degree of enhancement (p < 0.001). Inverse correlation was found between scan date and time to contrast (p = 0.001) and scan date and enhancement (p = 0.021). Conclusion FFLs should no longer be considered exclusionary for the diagnosis of VMs. Timing following contrast administration should be maximized to increase degree of enhancement to confirm the diagnosis of VMs. [ABSTRACT FROM AUTHOR]