Radiologic Evaluation of Intracranial Tumors

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Radiologic Evaluation of Intracranial Tumors

  1. 1. Radiologic Evaluation ofRadiologic Evaluation of Intracranial TumorsIntracranial Tumors Todd Gourdin M-IV Radiology Final Presentation August 2, 2007
  2. 2. Available ModalitiesAvailable Modalities 1)X-ray1)X-ray 2)CT2)CT 3)MRI3)MRI 4)Nuclear Medicine4)Nuclear Medicine
  3. 3. X-rayX-ray - Primarily of historical interest since thePrimarily of historical interest since the onset of CT in 1974.onset of CT in 1974. - Was useful for detecting increasedWas useful for detecting increased intracranial pressure and intracranialintracranial pressure and intracranial calcifications.calcifications.
  4. 4. CraniopharnygiomaCraniopharnygioma
  5. 5. CTCT - Most intracranial neoplasms are visible onMost intracranial neoplasms are visible on CTCT - Tumors may be hypodense, isodense, orTumors may be hypodense, isodense, or hyperdense on a noncontrast CThyperdense on a noncontrast CT depending on tumor histology and locationdepending on tumor histology and location
  6. 6. Pilocytic CerebellarPilocytic Cerebellar AstrocytomaAstrocytoma
  7. 7. Metastatic LesionMetastatic Lesion
  8. 8. - Small tumors or isodense tumors may beSmall tumors or isodense tumors may be missed on noncontrast CT but highlightmissed on noncontrast CT but highlight after contrast administrationafter contrast administration - Meningiomas and Neuromas enhance- Meningiomas and Neuromas enhance strongly with contrast while low-gradestrongly with contrast while low-grade gliomas and epidermoid tumors do notgliomas and epidermoid tumors do not enhance.enhance.
  9. 9. Why not MRI them all???Why not MRI them all??? - MRI is generally preferable to CT forMRI is generally preferable to CT for evaluating intracranial neoplasmsevaluating intracranial neoplasms - CT is preferred for visualizing tumorCT is preferred for visualizing tumor calcification or intratumor hemorrhage.calcification or intratumor hemorrhage.
  10. 10. Commonly Calcified andCommonly Calcified and Hemorrhagic LesionsHemorrhagic Lesions CalcifiedCalcified HemorrhagicHemorrhagic Oligodendroglioma Glioblastoma multiformeOligodendroglioma Glioblastoma multiforme Choroid Plexus tumor OligodendrogliomaChoroid Plexus tumor Oligodendroglioma Ependymoma Metastatic:Ependymoma Metastatic: Central neurocytoma MelanomaCentral neurocytoma Melanoma Craniopharyngioma BreastCraniopharyngioma Breast Teratoma LungTeratoma Lung ChordomaChordoma
  11. 11. EpendymomaEpendymoma
  12. 12. Glioblastoma MultiformeGlioblastoma Multiforme
  13. 13. MRIMRI - Usually the preferred method of imagingUsually the preferred method of imaging intracranial tumors due to better soft-intracranial tumors due to better soft- tissue contrasttissue contrast - MRI exploits increased water content ofMRI exploits increased water content of many neoplasms. This water contentmany neoplasms. This water content shows up as increased signal on T2shows up as increased signal on T2 weighted images and decreased signal onweighted images and decreased signal on T1 Images.T1 Images.
  14. 14. Noncontrast MRI of MeningiomaNoncontrast MRI of Meningioma T2T1
  15. 15. Contrast(often IVContrast(often IV Gadolinium) helpsGadolinium) helps visualize small tumorsvisualize small tumors that don’t cause muchthat don’t cause much edema.edema.
  16. 16. Advanced MRI TechniquesAdvanced MRI Techniques “This stuff is complicated!!!!”
  17. 17. Proton Magnetic ResonanceProton Magnetic Resonance SpectroscopySpectroscopy - Analyzes the biochemical makeup of aAnalyzes the biochemical makeup of a tumor to create a characteristictumor to create a characteristic spectroscopic pattern.spectroscopic pattern. - Computer analysis of the pattern allows- Computer analysis of the pattern allows histologic type to be determined non-histologic type to be determined non- invasively.invasively.
  18. 18. Figure 98-3 Proton magnetic resonance spectroscopy; the choline peak (3.22 p.p.m.) is elevated, the creatine peak (3.03 p.p.m.) is low and the N-acetyl aspartate peak (2.01 p.p.m.) is nearly undetectable; characteristic spectroscopic appearance of gliomas (choline—CHO; creatine—PCr/Cr; N-acetyl aspartate—NAA). “Grainger and Allison’s Diagnostic Radiology, 2001”
  19. 19. Perfusion weighted MRIPerfusion weighted MRI - Technique used to determine the relativeTechnique used to determine the relative cerebral blood volume (rCBV) ofcerebral blood volume (rCBV) of intracranial structures.intracranial structures. - Many tumors are highly vascularized- Many tumors are highly vascularized allowing them to be distinguished from theallowing them to be distinguished from the background on a perfusion weighted MRI.background on a perfusion weighted MRI.
  20. 20. MeningiomaMeningioma T2 Contrasted T1 Perfusion-Weighted
  21. 21. MRI-guided SurgeryMRI-guided Surgery - A variety of techniques have beenA variety of techniques have been developed to incorporate MRI into thedeveloped to incorporate MRI into the surgical process for intracranial tumorsurgical process for intracranial tumor resection:resection: MRI guided stereotactic biopsyMRI guided stereotactic biopsy Brain surface imagingBrain surface imaging Interventional MRIInterventional MRI
  22. 22. Brain Surface ImagingBrain Surface Imaging
  23. 23. Interventional MRIInterventional MRI
  24. 24. Nuclear MedicineNuclear Medicine SPECT(Single Photon Emission ComputedSPECT(Single Photon Emission Computed Tomography)Tomography) - Gamma rays emitted during radionuclideGamma rays emitted during radionuclide decay are detected by a gamma cameradecay are detected by a gamma camera that rotates about the patient’s headthat rotates about the patient’s head - The radionuclides must cross the blood-- The radionuclides must cross the blood- brain barrierbrain barrier
  25. 25. Radionuclides preferentially taken up byRadionuclides preferentially taken up by intracranial neoplasms include:intracranial neoplasms include: 201201 TI ChlorideTI Chloride 99m99m Tc MIBITc MIBI 123123 II αα-methyl tyrosine-methyl tyrosine 111111 In octreotideIn octreotide - Can be used for example in distinguishing- Can be used for example in distinguishing between benign lesions, low-grade gliomas, andbetween benign lesions, low-grade gliomas, and high-grade gliomashigh-grade gliomas
  26. 26. SPECT of Normal BrainSPECT of Normal Brain Radionuclide = 99m TC
  27. 27. 201201 T1 SPECTT1 SPECT Diagnosed by SPECT as a high-grade glioma and confirmed post-resection
  28. 28. PET(Positron EmissionPET(Positron Emission Tomography)Tomography) - Similar to SPECT but the radioisotopes used decay toSimilar to SPECT but the radioisotopes used decay to produce positronsproduce positrons - These positrons quickly combine with an adjacentThese positrons quickly combine with an adjacent electron to produce two gamma rays that travel inelectron to produce two gamma rays that travel in opposite directions. Detection of these gamma raysopposite directions. Detection of these gamma rays allows calculation of their exact point of origin.allows calculation of their exact point of origin. - Can evaluate different brain processes depending onCan evaluate different brain processes depending on the radioisotope selectedthe radioisotope selected
  29. 29. Radionuclides useful for PET analysis ofRadionuclides useful for PET analysis of intracranial tumors include:intracranial tumors include: FluorodeoxyglucoseFluorodeoxyglucose C methionineC methionine FF αα-methyl tyrosine-methyl tyrosine
  30. 30. Advantages of PET over SPECT:Advantages of PET over SPECT: - Can be used to quantify emission- Can be used to quantify emission - Better resolutionBetter resolution Disadvantages of PET:Disadvantages of PET: - CostCost - Limited availabilityLimited availability - Need for a cyclotron(particle accelerator)Need for a cyclotron(particle accelerator)
  31. 31. PET scan of Language CenterPET scan of Language Center Figure 98-4 H215O PET activation study during a language task in a young man with a right frontal glioma, before neurosurgical resection. Language activation is seen bilaterally and is distant from the tumour. “Grainger and Allison’s Diagnostic Radiology, 2001”
  32. 32. Classification of IntracranialClassification of Intracranial NeoplasmsNeoplasms 1)Neuroepithelial Origin –1)Neuroepithelial Origin – astrocytoma,astrocytoma, oligodendroglioma, ependymoma, mixed glioma, choroidoligodendroglioma, ependymoma, mixed glioma, choroid plexus tumor, neuronal tumor, pineal tumor.plexus tumor, neuronal tumor, pineal tumor. -Gliomas(astrocytomas, oligodendroglioma, ependymoma)-Gliomas(astrocytomas, oligodendroglioma, ependymoma) = approximately 50% of primary brain tumors= approximately 50% of primary brain tumors -Graded from 1 -4 based on severity-Graded from 1 -4 based on severity -Grade 4 = Glioblastoma Multiforme – most common-Grade 4 = Glioblastoma Multiforme – most common primary intracranial neoplasmprimary intracranial neoplasm
  33. 33. GBMGBM -Hallmark finding is tumor necrosis -Often cross the midline - Extremely poor prognosis
  34. 34. 2)Tumors of Nerve Sheath –2)Tumors of Nerve Sheath – Schwannoma,Schwannoma, NeurofibromaNeurofibroma - These are cranial nerve sheath tumors that show marked- These are cranial nerve sheath tumors that show marked enhancement with IV contrastenhancement with IV contrast
  35. 35. Bilateral schwannomas in NF typeBilateral schwannomas in NF type 22
  36. 36. 3)Meningeal tumors –3)Meningeal tumors – meningiomameningioma - Originate from “arachnoid cell rests” in the dura matterOriginate from “arachnoid cell rests” in the dura matter - Commonly arise from parasagittal region, cerebral convexities,Commonly arise from parasagittal region, cerebral convexities, sphenoid ridge, and olfactory groovesphenoid ridge, and olfactory groove - Often contain calcifications and enhance well with IV contrastOften contain calcifications and enhance well with IV contrast - Represents approximately 15% of primary intracranial tumorsRepresents approximately 15% of primary intracranial tumors
  37. 37. MeningiomaMeningioma
  38. 38. 4)Lymphoma4)Lymphoma - 2-3% of intracranial neoplasms2-3% of intracranial neoplasms - Well defined, rounded lesions that appear hyperdenseWell defined, rounded lesions that appear hyperdense on noncontrast CT and enhace well with contraston noncontrast CT and enhace well with contrast - Lymphomas may appear “atypical” in theLymphomas may appear “atypical” in the immunocompromisedimmunocompromised
  39. 39. Lymphoma on noncontrast/contrastLymphoma on noncontrast/contrast CTCT
  40. 40. 5)Metastasis5)Metastasis - Usually multiple lesions which help distinguish them fromUsually multiple lesions which help distinguish them from supratentorial gliomassupratentorial gliomas - Often found at grey/white matter junctionOften found at grey/white matter junction
  41. 41. MetastasesMetastases
  42. 42. 6)Additional classes include:6)Additional classes include: germ cell tumors,germ cell tumors, dermoid/epidermoid cysts, sellar/pituitary tumors,dermoid/epidermoid cysts, sellar/pituitary tumors,
  43. 43. Some famous people who haveSome famous people who have suffered from a brain tumorsuffered from a brain tumor
  44. 44. ReferencesReferences Harvard University Dept. of RadiologyHarvard University Dept. of Radiology www.brighamrad.harvard.eduwww.brighamrad.harvard.edu LSU Dept. of RadiologyLSU Dept. of Radiology www.medschool.lsuhsc.eduwww.medschool.lsuhsc.edu University of South Carolina Dept. of RadiologyUniversity of South Carolina Dept. of Radiology www.radiology.med.sc.eduwww.radiology.med.sc.edu Grainger and Allison’s Diagnostic Radiology: A Textbook of MedicalGrainger and Allison’s Diagnostic Radiology: A Textbook of Medical Imaging, 4Imaging, 4thth ed. 2001 Churchill Livinstone Inc., 2001.ed. 2001 Churchill Livinstone Inc., 2001.

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