Book contents
- Frontmatter
- Contents
- List of contributors
- List of abbreviations
- Preface
- Section 1 Bilateral Predominantly Symmetric Abnormalities
- Section 2 Sellar, Perisellar and Midline Lesions
- Section 3 Parenchymal Defects or Abnormal Volume
- Section 4 Abnormalities Without Significant Mass Effect
- Section 5 Primarily Extra-Axial Focal Space-Occupying Lesions
- Section 6 Primarily Intra-Axial Masses
- 152 Acute Infarction
- 153 Glioblastoma Multiforme
- 154 Therapy-Induced Cerebral Necrosis (Radiation Necrosis)
- 155 Non-Hemorrhagic Metastases
- 156 Cerebral Abscess
- 157 Cerebral Toxoplasmosis
- 158 Primary CNS Lymphoma
- 159 Tumefactive Demyelinating Lesion
- 160 Tuberculoma
- 161 Oligodendroglioma
- 162 Low-Grade Diffuse Astrocytoma
- 163 Gliomatosis Cerebri
- 164 Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS)
- 165 Pleomorphic Xanthoastrocytoma (PXA)
- 166 Ganglioglioma
- 167 Neurocysticercosis – Parenchymal
- 168 Dilated Perivascular Spaces
- 169 Neuroepithelial Cyst
- 170 Subependymal Giant Cell Astrocytoma (SEGA)
- 171 Subependymoma
- 172 Ependymoma
- 173 Pilocytic Astrocytoma
- 174 Medulloblastoma
- 175 Hemangioblastoma
- 176 Lhermitte–Duclos (Cowden Syndrome)
- 177 Hypertensive Hematoma
- 178 Amyloid Hemorrhage – Cerebral Amyloid Angiopathy
- 179 Cortical Contusion
- 180 Hemorrhagic Neoplasms
- 181 Hemorrhagic Venous Thrombosis
- 182 Arteriovenous Malformation
- 183 Cavernous Angioma (Cavernoma)
- Section 7 Intracranial Calcifications
- Index
- References
173 - Pilocytic Astrocytoma
from Section 6 - Primarily Intra-Axial Masses
Published online by Cambridge University Press: 05 August 2013
- Frontmatter
- Contents
- List of contributors
- List of abbreviations
- Preface
- Section 1 Bilateral Predominantly Symmetric Abnormalities
- Section 2 Sellar, Perisellar and Midline Lesions
- Section 3 Parenchymal Defects or Abnormal Volume
- Section 4 Abnormalities Without Significant Mass Effect
- Section 5 Primarily Extra-Axial Focal Space-Occupying Lesions
- Section 6 Primarily Intra-Axial Masses
- 152 Acute Infarction
- 153 Glioblastoma Multiforme
- 154 Therapy-Induced Cerebral Necrosis (Radiation Necrosis)
- 155 Non-Hemorrhagic Metastases
- 156 Cerebral Abscess
- 157 Cerebral Toxoplasmosis
- 158 Primary CNS Lymphoma
- 159 Tumefactive Demyelinating Lesion
- 160 Tuberculoma
- 161 Oligodendroglioma
- 162 Low-Grade Diffuse Astrocytoma
- 163 Gliomatosis Cerebri
- 164 Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS)
- 165 Pleomorphic Xanthoastrocytoma (PXA)
- 166 Ganglioglioma
- 167 Neurocysticercosis – Parenchymal
- 168 Dilated Perivascular Spaces
- 169 Neuroepithelial Cyst
- 170 Subependymal Giant Cell Astrocytoma (SEGA)
- 171 Subependymoma
- 172 Ependymoma
- 173 Pilocytic Astrocytoma
- 174 Medulloblastoma
- 175 Hemangioblastoma
- 176 Lhermitte–Duclos (Cowden Syndrome)
- 177 Hypertensive Hematoma
- 178 Amyloid Hemorrhage – Cerebral Amyloid Angiopathy
- 179 Cortical Contusion
- 180 Hemorrhagic Neoplasms
- 181 Hemorrhagic Venous Thrombosis
- 182 Arteriovenous Malformation
- 183 Cavernous Angioma (Cavernoma)
- Section 7 Intracranial Calcifications
- Index
- References
Summary
Specific Imaging Findings
The classic imaging appearance of a pilocytic astrocytoma (PA) is a well circumscribed cerebellar/fourth ventricle mass composed of a cyst and intensely enhancing mural nodule. This appearance is, however, absent in many cases of PA and is common with other neoplasms in this location and age group. The cysts are frequently absent, but the solid portions are characteristically hypodense on CT, T1 hypointense and of very high T2 signal. PAs typically exhibit avid contrast enhancement, which may be partial and patchy, and non-enhancing solid portions may also be present. The tumors ar3e bright on ADC maps, approaching the CSF signal. This very high diffusion is essentially pathognomonic for pediatric posterior fossa PA. Peritumoral edema is typically minimal or absent. PAs also occur in the brainstem, usually as well circumscribed, exophytic lesions. Supratentorial PAs commonly involve the optic pathways and hypothalamus. Perfusion imaging reveals relative cerebral blood volume to be only mildly elevated or similar to the normal brain. PAs are also found in adults and these tumors show the same imaging characteristics as in the pediatric population.
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- Brain Imaging with MRI and CTAn Image Pattern Approach, pp. 357 - 358Publisher: Cambridge University PressPrint publication year: 2012