"Note: This article focuses primarily on supratentorial parenchymal and extra-axial masses in adults. For approaches to other scenarios please refer to:"
"Note: This article focuses primarily on supratentorial parenchymal and extra-axial masses in adults. For approaches to other scenarios please refer to:"
"Peripheral enhancement, often referred to as ring enhancement, is the most common pattern. The most important diagnosis that needs to be considered and not missed whenever presented with an intra-parenchymal mass which demonstrates peripheral enhancement is that of a cerebral abscess. Surgical drainage in most cases is a matter of urgency; "never let the sun set on an undrained abscess". Having said that, being too timid in dismissing the possibility of a lesion representing an abscess is also a failing."
"Solid enhancement is seen predominantly in high grade astrocytomas (WHO III or IV), cerebral metastases or CNS lymphoma. Each of these has a few helpful clues."
"Irregular enhancement is a relatively uncommon presentation. In addition to diffuse gliomas (e.g. anaplastic astrocytoma; gemistocytic astrocytoma) and tumefactive demyelination, the main differential is that of a subacute cerebral infarction."
"The two most useful signs are identifying a CSF cleft (with interposition of pial vessels between the mass and the cortex) and white matter buckling sign. Presence of a dural tail is also quite helpful, although one must be mindful of placing too much emphasis on this well known sign as a number of intraparenchymal masses can also result in reactive dural thickening (e.g. PXA)."
"A crucial diagnosis to not be missed is HSV encephalitis. Usually presentation will be helpful, with patients having a short clinical decline. In some instances the presentation will be less obvious (often due to co-morbidities). The pattern of involvement in immunocompetent adults is usually bilateral but asymmetrical involvement of the limbic system, medial temporal lobes, insular cortices and inferolateral frontal lobes. The basal ganglia are typically spared. Some enhancement usually develops later in the course of disease."
"For a more in depth discussion on distinguishing metastases for GBM see glioblastoma vs cerebral metastasis."
"presumptive diagnosis of cerebral abscess or HSV encephalitis"
"Wernicke's area and Broca's area for language"
"There are three main patterns of enhancement: peripheral, solid and irregular."
"Peripheral enhancement, often referred to as ring enhancement, is the most common pattern. The most important diagnosis that needs to be considered and not missed whenever presented with an intra-parenchymal mass which demonstrates peripheral enhancement is that of a cerebral abscess. Surgical drainage in most cases is a matter of urgency; "never let the sun set on an undrained abscess". Having said that, being too timid in dismissing the possibility of a lesion representing an abscess is also a failing."
"Peripheral enhancement, often referred to as ring enhancement, is the most common pattern. The most important diagnosis that needs to be considered and not missed whenever presented with an intra-parenchymal mass which demonstrates peripheral enhancement is that of a cerebral abscess. Surgical drainage in most cases is a matter of urgency; "never let the sun set on an undrained abscess". Having said that, being too timid in dismissing the possibility of a lesion representing an abscess is also a failing."
"In most cases of cerebral haemorrhage, an obvious clinical event will be evident and acute imaging with CT will have been obtained. In some cases though, particularly in the infirm elderly, this will not have occurred and it falls to the radiologist to make the diagnosis. Firstly, it is important to take the location of the lesion into account as most will either be a basal ganglia haemorrhages or lobar haemorrhages. Careful scrutiny of SWI images for appropriate distribution of microhaemorrhages is a helpful corroborating piece of evidence."
Expected headings
"Imaging protocol"
"Localisation"
"Extra-axial vs intra-axial"
"Extra-axial"
"Intra-axial"
"Anatomical localisation"
"Likely diagnosis"
"Extra-axial masses"
"Intra-axial masses"
"Non-enhancing masses"
"Enhancing masses"
"Time critical findings"
"Interpreting histology"
"Before one can embark upon this task, appropriate imaging needs to be available. A good quality MRI with a combination of structural and advanced imaging is crucial (e.g. MRI brain tumour protocol)."
"The first step in correct localisation is determining if the mass is intra-axial or extra-axial. In many instances this is self evident, however, not infrequently the differentiation can be challenging. This is especially the case in the setting of a large peripheral heterogeneous mass (e.g. case 1 vs case 2)."
"The two most useful signs are identifying a CSF cleft (with interposition of pial vessels between the mass and the cortex) and white matter buckling sign. Presence of a dural tail is also quite helpful, although one must be mindful of placing too much emphasis on this well known sign as a number of intraparenchymal masses can also result in reactive dural thickening (e.g. PXA)."
"are there nearby vascular structures that are going to be at risk? (e.g. displaced or encased arteries; large overlying veins)"
"amygdala, hippocampus and fornix"
"are the dural venous sinuses compressed, invaded or occluded?"
"Although the list of possible entities resulting in an intracranial mass (even excluding intraventricular, pineal and pituitary mass) is very long, limiting your attention to a handful of entities will allow you to make the correct diagnosis in the vast majority of cases. There are many situations where less common entities should be considered; this is beyond the scope of this article."
"There are three main patterns of enhancement: peripheral, solid and irregular."
"CNS lymphoma is the poster-child of solid enhancement, typically demonstrating very homogeneous vivid contrast enhancement with slightly blurry margins. These tumours are very cellular (small round blue cell tumours) and thus demonstrate low ADC values and are hyperdense on non-contrast CT. Lymphoma has a predilection for periventricular white matter, including the corpus callosum, cortex and deep grey matter. It is important to note that distribution, enhancement and morphology are significantly altered with immunosuppression or administration of steroids."
"CNS lymphoma is the poster-child of solid enhancement, typically demonstrating very homogeneous vivid contrast enhancement with slightly blurry margins. These tumours are very cellular (small round blue cell tumours) and thus demonstrate low ADC values and are hyperdense on non-contrast CT. Lymphoma has a predilection for periventricular white matter, including the corpus callosum, cortex and deep grey matter. It is important to note that distribution, enhancement and morphology are significantly altered with immunosuppression or administration of steroids."
"it should localise the mass as being intra- or extra-axial, anatomically and relative to eloquent areas and vascular structures"
"are there nearby vascular structures that are going to be at risk? (e.g. displaced or encased arteries; large overlying veins)"
"Although the list of possible entities resulting in an intracranial mass (even excluding intraventricular, pineal and pituitary mass) is very long, limiting your attention to a handful of entities will allow you to make the correct diagnosis in the vast majority of cases. There are many situations where less common entities should be considered; this is beyond the scope of this article."
"Peripheral enhancement, often referred to as ring enhancement, is the most common pattern. The most important diagnosis that needs to be considered and not missed whenever presented with an intra-parenchymal mass which demonstrates peripheral enhancement is that of a cerebral abscess. Surgical drainage in most cases is a matter of urgency; "never let the sun set on an undrained abscess". Having said that, being too timid in dismissing the possibility of a lesion representing an abscess is also a failing."
"Secondly, the lesion itself will demonstrate central signal of altered blood product (variable depending on timing; see ageing blood on MRI). The peripheral enhancement is usually relatively minor, without solid / nodular components. Surrounding the mass a variable amount of vasogenic oedema will be present, but no non-enhancing cortical expansion will be visible."
"Irregular enhancement is a relatively uncommon presentation. In addition to diffuse gliomas (e.g. anaplastic astrocytoma; gemistocytic astrocytoma) and tumefactive demyelination, the main differential is that of a subacute cerebral infarction."
"Although the list of possible entities resulting in an intracranial mass (even excluding intraventricular, pineal and pituitary mass) is very long, limiting your attention to a handful of entities will allow you to make the correct diagnosis in the vast majority of cases. There are many situations where less common entities should be considered; this is beyond the scope of this article."
"There are three main patterns of enhancement: peripheral, solid and irregular."
"There are a number of features that are helpful in suggesting the diagnosis or cerebral abscess:"