Benign brain lesions

Transcription

1 Benign brain lesions Diagnostic and Interventional Radiology Hung-Wen Kao Department of Radiology, Tri-Service General Hospital, National Defense Medical Center

2 Computed tomography Hounsfield unit (HU) of tissues and window settings Psychiatr. Clin. North Am Dec;33(4):

3 Traumatic injuries in different window settings Psychiatr. Clin. North Am Dec;33(4):

4 Skull fracture in different window settings Psychiatr. Clin. North Am Dec;33(4):

5 Magnetic resonance (MR) imaging

6 MR imaging T1-weighted T2-weighted FLAIR Fluid-attenuated-inversion-recovery

7 MR imaging Axial contrastenhanced Coronal contrastenhanced Diffusion-weighted image, DWI

8 MR imaging MR tractography MR angiography Functional MR imaging

9 Types of brain lesions Vascular Inflammatory/infectious Neoplasm: benign or malignant Degenerative/deficiency/drugs Intoxication/iatrogenic/idiopathic Congenital Autoimmune/allergic/anatomic Traumatic Endocrine/environmental

10 Vascular Ischemic stroke Hemorrhagic stroke Hypoxic ischemic injury

11 Stroke Ischemic: 80% Thrombotic Age, DM, HTN Embolic Systemic hypoperfusion Hemorrhagic: 20% Intracerebral HTN, trauma, bleeding diatheses, illicit drugs (eg, amphetamines, cocaine), vascular malformations

12 Ischemic stroke Not obvious on CT in a few hours after symptom onset The most accurate imaging modality: diffusion-weighted image (DWI) Evident in 30 minutes after symptom onset Cytotoxic edema

13 Intra-arterial thrombolysis with urokinase

14 Interventional neuroradiology MERCI Retrieval System, FDA-approved Penumbra System, FDAapproved EKOS ultrasound device

15 Hemorrhagic stroke

16 Hemorrhagic stroke Acute: 65 HU 8 days: 45 HU Initial hematoma: HU Acute stage: HU Fibrin clot (minutes to hours after rupture) 13 days 5 months Later: HU Clot retraction and extrusion of serum Magn Reson Imaging Clin N Am May;14(2): v.

17 MR imaging of hematomas chemical state of the iron atoms within the hemoglobin molecule paramagnetic Hyperacute dipole dipole interactions shorten both the T1 and T2 relaxation times, more on T1 susceptibility effects present when iron atoms are compartmentalized within the red cell membrane Acute Shorten the T2 relaxation time integrity of the red blood cell membrane Early subacute

18 MR imaging of hematomas Late subacute Chronic

19 MR imaging of hematomas Oxyhemoglobin: diamagnetic, no unpaired electrons Deoxyhemoglobin: paramagnetic, 4 unpaired electrons Methemoglobin: magnetic dipole-dipole interactions Hemosiderin: > 10,000 unpaired electron, superparamagnetic

20 Hypoxic ischemic injury Cardiac arrest Carbon monoxide intoxication Poor gray-white matter differentiation

21 Infectious Brain asbscess Meningoencephalitis

22 Brian abscess Bacteria Necrotic lesion with rim enhancement and perifocal swelling of the brain tissue Hyperintensity on DWI

23 Meningoencephalitis Virus, bacteria Meningitis, encephalitis Contrast-enhanced MR imaging, DWI Linear meningeal enhancement, hyperintensity on DWI Herpes Simplex Encephalitis TB meningitis

24 Neoplasm Meningioma

25 Meningioma The most common extraaxial tumor 90% benign Typical imaging finding Isointensities on T1-weighted and T2- weighted images Homogeneous contrast enhancement Preoperative embolization

26 M/56 Nov. 20 Nov. 21

27 After embolization Nov. 21 Nov. 22

28 Congenital Arachnoid cyst & other benign cystic lesions of the brain Radiology. Radiological Society of North America; 2006;239(3):

29 Arachnoid cyst 1% of all intracranial masses In arachnoid space Filled with cerebrospinal fluid Smoothly marginated expansile lesion 60% in the middle cranial fossa No restriction on DWI

30

31

32 Epidermoid cyst Congenital inclusion cyst 0.2% 1.8% of primary intracranial tumors Most common in cerebellopontine angle cistern Imaging findings isointense or slightly hyperintense to CSF on both T1- and T2-weighted MR images High signal intensity on DWI

33 Dermoid cyst Rare congenital ectodermal inclusion cysts <.5% of primary intracranial tumors midline sellar, parasellar, or frontonasal regions increase in size by glandular secretion and epithelial desquamation Rupture, chemical meningitis vasospasm, infarction, even death Nonenhancing hyperintensities on T1-weighted images

34

35 Choroid plexus cyst nonneoplastic epithelial-lined cysts of the choroid plexus most common of all intracranial neuroepithelial cysts, up to 50% of autopsy cases asymptomatic and found incidentally

36 Ependymal cyst benign, ependymal-lined cysts of the lateral ventricle or juxtaventricular region of the temporoparietal region and frontal lobe thin-walled CSF-containing cyst of the lateral ventricle

37 Neuroglial cyst Congenital benign epitheliallined lesions that occur anywhere in the neuraxis < 1% of intracranial cysts Most typical in frontal lobe rounded, smooth, unilocular nonenhancing CSF-like parenchymal cyst with minimal to no surrounding signal intensity abnormality

38

39 Enlarged perivascular space Normal variant Virchow-Robin spaces Pial-lined interstitial fluid-filled structures accompaning penetrating arteries and veins inferior basal ganglia, clustering around the anterior commissure and surrounding the lenticulostriate arteries

40 Traumatic Subarachnoid hemorrhage Subdural hemorrhage Epidural hemorrhage

41 Subarachnoid hemorrhage Trauma or aneurysm rupture Hydrocephalus Parenchymal infarction

42 Aneurysm rupture

43 Subdural hemorrhage Laceration of bridging veins in subarachnoid space Crescent shape Can cross sutures Stop at midline Usually comes with parenchymal injury

44 Epidural hemorrhage Rupture of the middle meningeal artery Concomitant with skull fracture in 95% Fusiform, biconvex Can cross midline Stop at sutures

45 Benign brain lesions Vascular: ischemic stroke, hemorrhagic stroke, hypoxic ischemic injury Inflammatory/infectious: brain abscess, meningoencephalitis Neoplasm: benign or malignant: meningioma Intoxication/iatrogenic/idiopathic: CO intoxication Congenital: Arachnoid cyst and other cystic brain lesions Traumatic: SAH, SDH, EDH

46 Thanks for your attention