Sequential MRI and MR spectroscopy in embolized meningiomas: correlation with surgical and histopathological findings

Abstract

The preoperative embolization of meningiomas is commonly used to facilitate surgery. The purpose of this study was to evaluate the morphological and metabolic changes in embolized meningiomas and to correlate the results with surgical and histopathological findings. In a prospective study, 36 patients with intracranial meningiomas were included. The extent of devascularization was assessed by angiography and MR volumetry. MRI and MR spectroscopy (MRS) were performed before and sequentially after embolization. At surgery, blood loss was measured and intraoperative duplex-mode ultrasound was applied to identify avascular tumor portions. Histopathological specimens were evaluated for the histological subtype, localization and extent of necrotic tumor portions. Postembolization MRI revealed a variable pattern of secondary revascularization and devascularization with an early onset following embolization. In all patients, peripheral secondary enhancement was present which histopathologically represented a thin layer of vital tumor tissue. MRS revealed lactate in devascularized areas immediately after embolization. Lipids were not observed before the 3rd day after embolization and were always associated with avascular and soft tissue at the time of surgery. Embolized meningiomas feature a variable dynamic with the potential for revascularization and secondary devascularization. Lipid signals indicate avascular and soft tissue at surgery. In case of delayed surgery, MRI and MRS should be performed in order to exclude revascularization and to establish the fatty degeneration of the meningioma.

Use of proton magnetic resonance spectroscopy of the brain to differentiate gliomatosis cerebri from low-grade glioma

“…These findings are in accordance with those of previous studies in which MR spectroscopy had been applied to studying GC. 1,30 The elevated Cho level is related to cellular proliferation and the reduced NAA concentration corresponds to reversible neuronal injury and/or focal invasion by the tumor process. At a long echo time, Cho levels were more elevated in patients harboring LGGs than in those with GC.…”

Fatal Hemorrhage after Particle Embolization of an Intracranial Meningioma

“…Microsurgical removal is reported to be facilitated by improved intraoperative hemostasis [13]. Moreover, tumor softening due to necrosis has been observed after a period of time which ameliorated tumor resection [5]. In a selected group of patients (i.e., old patients with an increased surgical risk, or patients with multiple meningiomas), embolization without subsequent surgery has been suggested as palliative treatment to cause tumor shrinkage and to relieve the mass effect [2,3,21].…”

Meningeal Tumors

“…55 Comparing T1 post-gadolinium imaging to dynamic MR using a contrast bolus indicates that following embolization some areas of embolized tumor may enhance in a delayed fashion owing to slow collateral flow ( Figure 17). 56 On the basis of MR findings it has been suggested that MRI and MRS following embolization may serve a purpose to identify revascularization and establish the presence of fatty degeneration of the meningioma. The spectroscopic data indicate high concentrations of lactate at 24 h after embolization, followed by broad aliphatic signal several days later.…”