Intracerebral metastases MRI

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Brain MRI is helpful in the diagnosis of intracerebral metastases. On MRI, intracerebral metastases are characterized by iso- to hypointensity on T1-weighted imaging and hyperintense portion on T2-weighted imaging. On contrast administration, intense enhancement is observed (uniform, punctate, or ring-enhancing). Peritumoral edema which is out of proportion with tumor size is observed on diffusion weighted imaging.^[1]

• On MRI, brain metastases are typically found in the watershed areas of the brain (areas where blood vessels narrow and act as a trap for clumps of tumor cells).^[2]
• Findings on MRI suggestive of intracerebral metastases are tabulated below:^[1]

• 
  _{Brain metastasis in the right cerebral hemisphere from lung cancer shown on T1-weighted magnetic resonance imaging with intravenous contrast.^[3]}
• 
  _{Coronal T1 C+ head within the parieto-occipital region on the left demonstrates a very rounded brightly peripherally enhancing mass located near the grey-white junction, surrounded by a moderate amount of vasogenic edema. The central region of lower signal intensity does not enhance nor does it restrict. Features are consistent with the patient’s known metastatic disease with bull’s eye sign.^[4]}
• 
  _{Axial T2 MRI scan of 60 year old female with known history of malignant melanoma, complaining of acute right hemiplegia, aphasia, and confusion, demonstrates a large cerebral haematoma with a fluid-fluid level. There is a smaller low signal area anteriorly which corresponded to the known metastasis. This smaller area enhanced after gadolinium, as did the overlying dura.^[5]}
• 
  _{Axial T1 MRI scan of an elderly patient with history of small cell lung cancer, presenting with increasing headaches, demonstrates multiple cystic cerebral metastases.^[6]}
• 
  _{MRI head with contrast in a known case of renal cell carcinoma demonstrates multiple, large, well-defined, round, solid-cystic, peripheral irregular enhancement mass lesions involving left cerebral hemisphere and corpus callosum, crossing the midline anteriorly. Areas of necrosis and hemorrhage are seen within the lesion. Associated mass effect and moderate peritumoral edema is observed.^[7]}
• 
  _{A 40 year old female previously operated for metastatic brain lesion from Ca thyroid presents with altered sensorium. Patient earlier had thyroidectomy 1 year ago. Axial T2 MRI scan reveals left parietal lobe lesion with adjacent perilesional edema with an skull vault lesion at the previous craniotomy site. Skull vault lesion shows intense homogeneous enhancement.^[8]}
• 
  _{T1-weighted MRI head of a 65 year old male with advanced breast cancer demonstrates bilateral thalamic (and some smaller peripheral) metastases. The larger, partly cystic lesion on the right traverses the midline across the third ventricle.^[9]}
• 
  _{Axial FLAIR MRI head of a 60 year old male with known history of advanced colorectal cancer demonstrates multiple intracerebral metastases.^[10]}
• 
  _{Sagital T1-weighted MRI head of a 39 year old middle eastern female with breast cancer, complaining of headache and confusion, demonstrates multiple small scattered intraparenchymal ring enhancing lesions proved to be metastatic deposits.^[11]}
• 
  _{Axial T1-weighted MRI head with contrast of a 58 year old middle eastern male with pancoast tumor (adenocarcinoma), complaining of headache, vomiting, and syncopal attacks, demonstrates left cerebellar cystic lesion with fluid level with T1 hyperintense signal, likely hemorrhage. They show rim enhancement after contrast and surrounded by brain edema exerting mass effect upon the left lateral ventricle and left aspect of pons.^[12]}

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