Comparison of Perfusion, Diffusion, and MR Spectroscopy between Low-Grade Enhancing Pilocytic Astrocytomas and High-Grade Astrocytomas

Abstract

BACKGROUND AND PURPOSE:The differentiation of pilocytic astrocytomas and high-grade astrocytomas is sometimes difficult. There are limited comparisons in the literature of the advanced MR imaging findings of pilocytic astrocytomas versus high-grade astrocytomas. The purpose of this study was to assess the MR imaging, PWI, DWI, and MR spectroscopy characteristics of pilocytic astrocytomas compared with high-grade astrocytomas.

Role of Dynamic Contrast-Enhanced Perfusion Magnetic Resonance Imaging in Grading of Pediatric Brain Tumors on 3T

“…Our perfusion study results are in line with these histological observations where a high rCBV was observed in all of these tumors. However, previous perfusion studies have reported lower blood flow measurements in pilocytic astrocytomas compared to highergrade tumors [5,18,23] . In our study, we noted that ependymomas had a very high vascularity but, contrary to the results of the above mentioned studies, pilocytic astrocytomas were also found to be very vascular and showed a very high rCBV.…”

“…It was found to be more accurate than diffusion metrics and spectroscopic parameters for classifying adult gliomas [12] . Few studies have evaluated contrast-enhanced DSC perfusion MRI for grading of pediatric brain tumors, and all of them have found rCBV to be a useful parameter for discriminating high-grade neoplasms from low grade ones [7,17,18] . Arterial spin labeling perfusion techniques have also been used to grade pediatric brain tumors [5] .…”

Differentiation of hemangioblastomas from pilocytic astrocytomas using 3-T magnetic resonance perfusion-weighted imaging and MR spectroscopy

“…It may be worth noting that 14 cases of infratentorial PAs and 8 cases of supratentorial PAs recruited in the study presented similar imaging characteristics, and there was no significant difference in the parameters of rPH and rPSR between the PAs located in the posterior fossa and in the supratentorial region (data not shown). Proton MR spectroscopy can be used to acquire information on the metabolism of brain tissue [17,24]. NAA is generally thought to present in high concentrations in the normal neurons and axons, and its presence may be an indirect marker for tumor composition according to the density of residual neuronal cells within a tumor.…”

Adult anaplastic pilocytic astrocytoma – a diagnostic challenge? A case series and literature review

“…Elevated rCBV and cerebral blood flow (CBF) together with reduced ADC and decreased mean transit time (MTT) are suggestive of high-grade gliomas. Furthermore, magnetic resonance spectroscopy in high-grade gliomas typically shows high Cho/Cr and Cho/NAA ratios as well as lactate and mobile lipid resonances resulting from the higher cell membrane turnover as well as anaerobic metabolism and tumor necrosis [22][23][24]. In our series, all patients presented with non-specific clinical symptoms together with irregular contrast-enhancing lesions, which initially led to incorrect preoperative diagnoses of malignancy or demyelinating disease (Figs.…”