Conventional and Advanced Magnetic Resonance Imaging Features of Supratentorial Extraventricular Ependymomas

Abstract

Objective To describe the magnetic resonance imaging characteristics of supratentorial ependymomas. Methods The magnetic resonance imaging and computed tomography imaging characteristics of 49 cases of supratentorial ependymomas were analyzed retrospectively. The location, size, degree of perilesional edema, gross appearance, computed tomography attenuation characteristics, T1 and T2 signal intensity characteristics, degree of diffusion restriction, presence of calcification, and hemorrhage were documented for each lesion. The intratumoral susceptibility scores (ITSS), apparent diffusion coefficient (ADC) values, relative cerebral blood volume, and choline/N-acetyl aspartate ratios were documented where available. Results The frontal lobe was the most common location with a mean size of 6.37 × 4.8 cm. Severe perilesional edema was evident in 30%. Heterogenous, solid-cystic appearance was present in 96% lesions, with 95% of extraventricular lesions extending from pial surface to the ventricular margin. Calcification was seen in 55% of cases. The ITSS was 3 in 85.7% of lesions. The mean ADC value calculated was 600 × 10−6 mm2/s. The mean relative cerebral blood volume on dynamic susceptibility contrast perfusion was 4.83. The mean choline/N-acetyl aspartate ratio was 5.87. Leptomeningeal dissemination was demonstrable in 5 lesions. Four lesions were abutting the dura with frank dural invasion in one. One patient presented with disseminated disease without evidence of a primary lesion. Conclusions A large lesion with relatively well-defined margins, heterogeneous solid cystic appearance, extending from the pial surface to the ventricular margin, presence of calcification, and ADC values approaching those of white matter should raise a suspicion of supratentorial ependymoma. High ITSS, MR perfusion parameters, and magnetic resonance spectroscopy characteristics are similar to those of other high-grade gliomas.

Developing a Radiomics Signature for Supratentorial Extra-Ventricular Ependymoma Using Multimodal MR Imaging

“…Cyst and calcification are commonly occurring attributes of STEE tumors (4,7,9). Higher ADC values close to the white matter are also observed in these tumors (4). DWI and perfusion imaging illustrate restricted diffusion and high relative cerebral blood volume values, respectively, in STEEs, which are similar to high-grade anaplastic astrocytoma and glioblastoma (46).…”

“…Radiographic imaging markers of STEE tumors manifest on conventional MRI sequences as a heterogenous signal intensity on T1-and T2-weighted images and as variable appearance on FLAIR images (2,(5)(6)(7)(8). Cyst and calcification are commonly occurring attributes of STEE tumors (4,7,9). Higher ADC values close to the white matter are also observed in these tumors (4).…”

“…Existing literature illustrates that more than 25% of adult ependymoma can be mis-diagnosed, thus, elevating the importance of an accurate diagnosis (2). This is especially true in delineating extraventricular supratentorial ependymomas (STEE) from highgrade gliomas (HGG) as the appearance of ependymoma may closely resemble that of a glioblastoma on a magnetic resonance image (MRI) (2)(3)(4). STEEs generally appear hypointense on T1-weighted imaging, hyperintense on T2-weighted imaging, with an intermediate to high signal intensity on fluid-attenuated inversion recovery (FLAIR) images and may demonstrate ringor wreath-like contrast enhancement on gadolinium based T1weighted imaging as shown in Figure 1 (2,(5)(6)(7)(8).…”

“…Moreover, these lesions demonstrate marked heterogeneity within the tumor. Cystic formation can be noted very frequently, and calcifications are also common that can be seen in ∼50% of ependymomas (4,7,9). Diffusion-weighted imaging (DWI) from ependymoma demonstrates restricted diffusion within the solid tumor compartment indicating high cellularity of the lesion, while perfusion MRI shows marked increase in cerebral blood volume.…”

An Insight into Pathophysiological Features and Therapeutic Advances on Ependymoma

“…The dissemination of ependymoma, found in 11.4% of cases [19], affects extraneural organs such as the lungs, liver, and kidneys. Both magnetic resonance imaging (MRI) and computed tomography (CT) are used to diagnose ependymoma [20,21]. MRI is often used as a primary diagnosing procedure for better contrast and image quality [21,22].…”