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MRI of high-grade astrocytic tumors: early appearance and evolution
K Okamoto1, J Ito, N Takahashi
1Department of Radiology, Niigata University Faculty of Medicine, 1-757 Asahimachi-dori, Japan. nradioko@med.niigata-u.ac.jp
Abstract:
The clinical management and prognosis of patients with diffusely infiltrating astrocytomas are dependent on neuropathological grading of the tumors. The characteristics of MR images of high-grade astrocytic tumors are well known, but the early MRI appearance and the MRI evolution of high-grade astrocytic tumors have rarely been examined. We retrospectively reviewed MR images obtained from 4 months to 3 years and 3 months before admission, as well as MR images on admission, for five patients with pathologically proven high-grade astrocytic tumors (two glioblastomas and three anaplastic astrocytomas). In two patients, neoplastic lesions were not detectable on initial MRI, even retrospectively. In the remaining three patients, however, hyperintense areas with little or no mass effect were demonstrated on T2-weighted imaging. These lesions were misinterpreted as non-neoplastic processes, such as ischemic lesion or infarction, or demyelinating processes. All tumors showed gadolinium enhancement on admission, that emerged from the previously existing hyperintense areas on T2-weighted images without gadolinium enhancement, except for one de novo glioblastoma. Development of a small central cyst without gadolinium enhancement was demonstrated in one case before the emergence of an enhancing area.
Insights
Early magnetic resonance imaging (MRI) of high-grade astrocytic tumors may show subtle T2-weighted hyperintensities mistaken for non-neoplastic conditions. These early findings can evolve into enhancing lesions, impacting clinical management and prognosis.
Area of Science:
- Neuropathology
- Neuroradiology
- Oncology
Background:
- Clinical management and prognosis of diffusely infiltrating astrocytomas rely on accurate neuropathological grading.
- While high-grade astrocytic tumor MRI characteristics are known, their early appearance and evolution are less understood.
Purpose of the Study:
- To examine the early magnetic resonance imaging (MRI) appearance and evolution of high-grade astrocytic tumors.
- To compare initial and admission MRI findings with pathological diagnoses.
Main Methods:
- Retrospective review of MRI scans from five patients with pathologically proven high-grade astrocytic tumors (two glioblastomas, three anaplastic astrocytomas).
- Scans were analyzed from 4 months to over 3 years prior to admission and on admission.
Main Results:
- In two patients, initial MRI (even retrospective) failed to detect neoplastic lesions.
- Three patients showed T2-weighted hyperintensities with minimal mass effect, often misinterpreted as ischemic or demyelinating lesions.
- All tumors exhibited gadolinium enhancement on admission, originating from pre-existing T2 hyperintense areas, except for one de novo glioblastoma.
- A central cyst without enhancement preceded enhancement in one case.
Conclusions:
- Early MRI findings in high-grade astrocytic tumors can be subtle and non-specific, potentially leading to misdiagnosis.
- The evolution from non-enhancing T2 hyperintensities to enhancing lesions highlights the dynamic nature of these tumors on MRI.
- Understanding these early MRI changes is crucial for timely diagnosis and appropriate clinical management of high-grade astrocytic tumors.