Diagnosis of a meningioma is generally established by routine CT and/or MR imaging that determines the tumor morphology and composition. If the meningioma is fairly vascular and resection is planned, preoperative embolization is helpful in diminishing operative time and intraoperative blood loss. In routine practice, a diagnostic arteriogram is performed to identify blood supply and to assess the safety and feasibility of embolization, and if deemed appropriate, embolic material is then delivered to produce devascularization and subsequent necrosis of the tumor. X-ray fluoroscopy has excellent spatial and temporal resolution but is limited in that it is a projection modality that does not provide a full 3D analysis of the territory of interest. Preliminary results indicate that it is less sensitive to the transit of contrast material than is perfusion MRI, and has a limited ability to extract functional parameters, such as perfusion time constants or flow velocities. It is therefore likely that x-ray fluoroscopy fails to identify all patients who would benefit from embolization. Interventional MRI is attractive because of its sensitivity to intra-arterial injections of MR contrast agents and its ability to determine functional parameters. However, catheters suitable for human use in the interventional MRI setting must be metal-free because of concerns of heating-related injury, restricting the wide dissemination of this technology. The goal of this project is to determine the relative capability of MR perfusion and x-ray fluoroscopy in determining which meningiomas are candidates for embolization. This project will further assess whether MR perfusion time curves can determine the relative contribution of tumor vascularity that arises from the external versus the internal carotid artery, and whether intra-venous measurements of MR perfusion time curves are able to provide similar data to that of intra-arterial measurements. If that is the case, this project could establish whether intra- venous MR can identify those patients who are not candidates for embolization therapy, thereby sparing them an invasive arteriogram. Finally, this project will investigate, in a series of carefully controlled model experiments, whether specific pulse sequences with suitable imaging parameters can be used without causing untoward heating in certain metal-clad catheters. Public Health Relevance: This study will determine if MR can be used to more effectively stage patients for meningioma embolization, sparing patients from catheterization if embolization will not be effective, and including patients who would benefit from embolization, and who might not receive that benefit on the basis of x-ray fluoroscopy evaluation, alone. In addition, satisfactory demonstration of MR conditions under which metal-clad catheters could be safely used would enable expanded capabilities, not only for treatment of meningiomas, but in a broad range of exciting applications that are currently considered unapproachable. This study will determine if MR can be used to more effectively stage patients for meningioma embolization, sparing patients from catheterization if embolization will not be effective, and including patients who would benefit from embolization, and who might not receive that benefit on the basis of x-ray fluoroscopy evaluation, alone. In addition, satisfactory demonstration of MR conditions under which metal-clad catheters could be safely used would enable expanded capabilities, not only for treatment of meningiomas, but in a broad range of exciting applications that are currently considered unapproachable. ? ? ?
| Saloner, D; Uzelac, A; Hetts, S et al. (2010) Modern meningioma imaging techniques. J Neurooncol 99:333-40 |
