Abstract
PurposeGlioblastoma and anaplastic astrocytoma represent the most commonly encountered high-grade-glioma (HGG) in adults. Although both neoplasms are very distinct entities in context of epidemiology, clinical course and prognosis, their appearance in conventional magnetic resonance imaging (MRI) is very similar. In search for additional information aiding the distinction of potentially confusable neoplasms, histogram analysis of apparent diffusion coefficient (ADC) maps recently proved to be auxiliary in a number of entities. Therefore, our present exploratory retrospective study investigated whether ADC histogram profile parameters differ significantly between anaplastic astrocytoma and glioblastoma, reflect the proliferation index Ki-67, or are associated with the prognostic relevant MGMT (methylguanine-DNA methyl-transferase) promotor methylation status.MethodsPre-surgical ADC volumes of 56 HGG patients were analyzed by histogram-profiling. Association between extracted histogram parameters and neuropathology including WHO-grade, Ki-67 expression and MGMT promotor methylation status was investigated due to comparative and correlative statistics.ResultsGrade IV gliomas were more heterogeneous than grade III tumors. More specifically, ADCmin and the lowest percentile ADCp10 were significantly lower, whereas ADCmax, ADC standard deviation and Skewness were significantly higher in the glioblastoma group. ADCmin, ADCmax, ADC standard deviation, Kurtosis and Entropy of ADC histogram were significantly correlated with Ki-67 expression. No significant difference could be revealed by comparison of ADC histogram parameters between MGMT promotor methylated and unmethylated HGG.ConclusionsADC histogram parameters differ significantly between glioblastoma and anaplastic astrocytoma and show distinct associations with the proliferative activity in both HGG. Our results suggest ADC histogram profiling as promising biomarker for differentiation of both, however, further studies with prospective multicenter design are wanted to confirm and further elaborate this hypothesis.
Highlights
Gliomas belong to the group of primary central nervous system (CNS) neoplasias and develop from glial cells of the CNS
ADCmin and the lowest percentile ADCp10 were significantly lower, whereas ADCmax, apparent diffusion coefficient (ADC) standard deviation and Skewness were significantly higher in the glioblastoma group
ADCmin, ADCmax, ADC standard deviation, Kurtosis and Entropy of ADC histogram were significantly correlated with Ki-67 expression
Summary
Gliomas belong to the group of primary central nervous system (CNS) neoplasias and develop from glial cells of the CNS. Whereas entities of category WHO III and IV are considered as malign lesions, exhibiting aggressive tumor biology and classified as high-grade gliomas (HGG). The two most common HGG in adults are the glioblastoma (WHO IV) with about 14.9% and the anaplastic astrocytoma with about 1.7% of all newly diagnosed intracranial masses [1]. Glioblastoma, or astrocytoma WHO grade IV—the most fatal brain tumor in humans— remains associated with a median overall survival of 15 months [3] despite significant advances in understanding the underlying genetic, epigenetic and downstream alterations in the last decade [4]. Anaplastic astrocytoma (WHO III) exhibits a distinctly better prognosis with a median overall survival of 2 to 10 years, depending on associated genetic alterations like isocitrate dehydrogenase (IDH) mutation [2, 5, 6]
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