kathleen r. fink, md virginia mason medical center · kathleen r. fink, md virginia mason medical...

+

Kathleen R. Fink, MD

Virginia Mason Medical Center

6th Nordic Emergency Radiology Course 2017

+ Disclosure

My spouse receives research salary support from:

Guerbet

5/10/2017 KRF CNS infxn

+ Outline

Indications for imaging

CNS infections

Extra axial

Parenchymal

Vascular complications


+ Indications for Imaging

Suspected infection and:

Altered mental status

Seizures

Focal neurologic deficits

Immunocompromised patient with:

New headache

Any concerning sign


+ Imaging strategy

Non contrast head CT first choice

Rapid and widely available

Well tolerated by critically ill

patients

Exclude life threatening

conditions


Contrast enhanced MR More sensitive for subtle

findings - Leptomeningitis - Ventriculitis - Empyema - Infarction Consider strongly for

immunocompromised patients Can be problematic in sick

patients

Contrast enhanced head CT if: MR not immediately available Contraindications to MR

+ Imaging before LP?

Noncontrast CT can exclude contraindications

CT more likely to show a contraindication in patient with

(suspected meningitis) and:

• Age ≥ 60

• Immunocompromise

• Recent seizure

• Focal neurological deficit

• Impaired consciousness

Hasbun 2001 N Engl J Med 345:24, 1727-33 5/10/2017 KRF CNS infxn

+ Not safe to LP

Cerebral edema: •Poor gray-white differentiation

•Effaced sulci

•Effaced cisterns


+ Contraindications to LP

No absolute consensus on imaging contraindications.

General agreement on the following:

Midline shift

Effacement of the basal cisterns

Posterior fossa mass effect.

Clinical signs of herniation even with normal imaging.


+ Cautionary tale

4 PM, comatose 8 PM, after LP 5/10/2017 KRF CNS infxn

+

Extraaxial


+ 8 year old boy, sick one week


+ 8 year old boy, sick one week

Post contrast

Acute bacterial meningitis


+ Imaging in meningitis


CSF evaluation is diagnostic

Goal of imaging:

1) Exclude unexpected finding

2) Evaluate for complications:

- Infarction

- Hydrocephalus

- Ventriculitis

- Subdural effusions (kids), empyema

- Venous sinus thrombosis

+ Meningitis: Imaging

Imaging Findings:

NORMAL

Especially early

Leptomeningeal enhancement

• Hemispheric

• Basilar

• Subdural effusions (especially

children)

Ddx leptomeningeal

enhancement:

Leptomeningeal

spread of tumor

Neurosarcoidosis

CNS lymphoma


+ MRI: index case


T1 FLAIR

DWI/ADC

+ Meningitis: MRI

Imaging Findings:

FLAIR: high signal in

subarachnoid space due to

elevated protein

May see arterial narrowing due

to infectious arteritis with or

without infarction

Ddx: Subarachnoid FLAIR hyperintensities:

Subarachnoid hemorrhage

High inspired O2

Motion artifact

Altered perfusion/blood brain barrier

disruption

Leakage of gad (renal failure, eg)


+ 19 yo with worsening headache, nausea, and

vomiting.


Hydrocephalus!! NECT

+ MRI

5/10/2017 KRF CNS infxn T1 post

FLAIR

DWI/ADC

+ Tuberculous meningitis


Basilar meningitis:

Can present with

hydrocephalus due to thick

inflammatory exudate

Intracranial tuberculoma

Granulomatous lesions

Caseating or noncaseating

+/- necrotic center

Tuberculous abscess

Complications:

Vasculitis, infarcts

Patkar 2012. Neuroimaging Clin N Am 22:4, 677-705

+ Key Imaging Features

CT

Normal

Hydrocephalus

Isodense exudate in basilar cisterns

MR

Enhancing basilar leptomeninges

Infarcts

Tuberculomas: Solid, nodular or ring enhancement


+ Image Gallery


T1 post

DWI

Complications:

Infarcts

+

T1 pre

Basilar meningitis

Ddx: basilar meningitis:

Tuberculous meningitis

Pyogenic meningitis

Fungal meningitis

Neurosarcoidosis

Meningeal carcinomatosis

T1 post


+ Tuberculous meningitis

Basilar meningitis

+ infarcts: TB meningitis

Fungal meningitis, including

coccidioidomycosis

Basilar meningitis + parenchymal

lesions Think TB.


+ 53 year old man with recurrent facial cellulitis,

treated with antibiotics.


+ Subdural empyema

ADC

T1 Post

T1 T2


+ Subdural empyema:

CT: Isodense collection

MRI:

• T1 isointense (i.e proteinaceous

material)

• T2 hyperintense

• +/- restricted diffusion (dark ADC)

• Peripheral and meningeal

enhancement

• May see underlying cerebritis (as in

this case)

Subdural empyema, DDX:

Chronic Subdural hematoma

Subdural effusion (sterile CSF

collection associated with

meningitis)

Subdural hygroma

Dural based mets


+ Epidural abscess

Usually associated with head and

neck infection:

Sinusitis

Otomastoiditis

Post trauma

Post Surgery

*

+

Subdural empyema and

Epidural abscess can occur

together.

MRI may help differentiate.


+

Parenchymal


+ History: Feeling poorly for 3 weeks, bizarre

behavior x 1 day, seizure


+ History: Feeling poorly for 3 weeks, bizarre

behavior x 1 day, seizure


FLAIR

+ Herpes Encephalitis

Location:

Anterior and medial temporal

lobes

Insula

Lateral temporal lobes

Inferior frontal lobes

Cingulate


+ Key imaging features

Normal -OR-

Edema (low density)

Hemorrhage

Petechial

Along brain surface

Burned out:

Gliosis

Restricted diffusion may be

first

FLAIR

GRE for

microhemorrhages

May enhance


CT MRI

Tien et al 1993. AJR Am J Roentgenol 161:1, 167-76

+ Image gallery


NECT

FLAIR

DWI

+ Chronic changes of HSV encephalitis


+ Differential diagnosis:

Ischemia (including venous infarction)

Neoplasm

Limbic encephalitis

Other viral encephalitis (e.g. arboviral)

Favor HSV:

Bilateral

Nonvascular distribution

Normal basal ganglia


+ Arbovirus infection

Pathogenic viruses: Eastern equine

Western Equine

West Nile

Japanese

Tick-borne

Basal ganglia and thalami

lesions

T2, FLAIR, DWI

Ddx deep white matter: Anoxic/hypoxic injury

CO2, toxic exposures

Metabolic disorders (eg Wilson’s

disease)

Mitochondrial diseases

Creutzfeldt Jacob Eastern equine encephalitis.

Case courtesy of Mahmoud Mossa-Basha, MD 5/10/2017 KRF CNS infxn

+ History: 39 year old who fell


Current Study Comparison from 9 months prior

+

MRI


+ HIV-associated neurocognitive disorders (HAND)

Direct result of HIV on CNS

Findings on CT and MRI do not

predict cognitive dysfunction

CT:

Normal

Volume loss: sulcal or

ventricular enlargement

Patchy white matter

hypodensities




MRI:

Symmetric white matter

disease

May resemble age-related

volume loss or white matter

lesions of vascular origin,

but more than expected for

age

Spares Juxtacortical u-

fibers



FLAIR T2

+ Key Imaging Features: HIV


T1: occult DWI T1 post:

Non-enhancing

+ Differential Diagnosis

Age-related volume loss; white matter lesions of presumed

vascular origin (chronic ischemic change)

Hydrocephalus

Progressive multifocal leukoencephalopathy


+ History: 43 year old with HIV and low CD4 count

who presents with gait disturbance



T1 T1 post

T2 DWI

+ Progressive Multifocal Leukoencephalopathy

PML

Seen in certain clinical

scenarios:

HIV

Severe

immunosuppression

Multiple sclerosis on

natalizumab


+ PML

Imaging findings

Low density CT and T2

hyperintense areas

Little mass effect or

contrast enhancement

Parietal, occipital lobes

Asymmetric


+ Features favoring a diagnosis of PML over

HIV

Involvement of

subcortical u-

fibers


PML HIV


Sahraian. European Journal of Neurology 2012, 19: 1060–1069 doi:10.1111/j.1468-

1331.2011.03597.x

PML HIV

Confluent lesions, favors parieto-

occipital or CC

Normal or patchy periventricular

centrum semiovale lesions

Involves juxtacortical U fibers Spares U fibers

Asymmetric Symmetric

Low on T1 Usually isointense on T1

Low on DWI unless active

demyelination Isointense on DWI

Does not enhance unless IRIS

(immune reconstitution

inflammatory syndrome)

No enhancement

+ Image Gallery


Posterior fossa involvement

+ Image Gallery


T2

NECT

T1 post

DWI

ADC

PML IRIS

+ History: 33 year old with nausea, vomiting

and right sided weakness


+ Neurocysticercosis


Taenia solium, pork tapeworm

Cyst with central dot

Central dot is scolex

Four pathologic stages: Simple

cyst complex cystic lesion

calcification


Stage CT Findings MR Findings

Noncystic (Active asymptomatic)

Normal Normal

Vesicular (Cyst or cluster of cysts

with scolex)

1-2 cm cyst Simple appearing fluid

No edema. Scolex

Thin-walled cyst Follows CSF

Little enhancement. Scolex

Colloidal vesicular (Larva degenerates,

inflammatory response begins)

Cyst may be dense Enhances ± Edema

Proteinaceous cyst Thick walled

Edema Enhancement

Granular nodular (Cyst retracts and

granulomatous reaction ensues)

Edema increases. Thick ring enhancement

Edema increases. Thick ring enhancement

Calcified nodular (Inactive)

Calcific nodules without edema or enhancement

Hypointense nodules without edema or

enhancement Kimura-Hayama Radiographics 2010 Oct;30(6):1705-19.

doi: 10.1148/rg.306105522.

+ Key Imaging Features


T2

NECT

T1 post

DWI

ADC

+ Image Gallery


Subarachnoid

Intraventricular cysts can cause

hydrocephalus.

Calcified nodular phase


Pyogenic abscess (no scolex)

Ring enhancing mass:

Metastasis

Glioblastoma multiforme

Lymphoma in immunocompromised patient

Etc.


+ History: 38 year old with recurrent sinus infections,

worsening headache, nausea and vomiting


+ Contrast

+ MRI:


FLAIR

T1

T1 post

DWI

ADC

+ Pyogenic abscess


Focal pus collection with

surrounding capsule.

Direct extension

Sinusitis

Otomastoiditis

Odontogenic

Hematogenous

IVDA

Endocarditis

Pulmonary AVF

+ Pyogenic abscess


Parenchymal mass

Gray-white junction

Low T2 ring

Hyperintense necrotic core

Rim enhancement

• Thick smooth

• Thinned medial wall

Restricted diffusion of central

necrotic core

Daughter cells

Look for ventricular extension

+


Image gallery

+ Cerebritis


2 days later

DWI

T1 post

FLAIR

FLAIR

T1 post

+ Abscess development


13 days later

Early cerebritis

Ill defined edema

Late cerebritis

Central low density

Early capsule

Thin rim enhancement

Late capsule

Thick rim enhancement Britt J Neurosurg 1983 December;59(6):972-89.

+ History: 40 yo with HIV and 2 days of

headache, blurry vision, gait disturbance


+ MRI: Vital in Immunocompromised


+ Toxoplasmosis


Toxoplasma gondii

Reactivation of latent infection in immunocompromised patient

Masses:

Ring enhancing

T2 heterogeneous

No restricted DWI of central necrotic portion

Location:

Basal ganglia

Thalamus

Gray-white junction

Akgoz et al. Neuroimaging Clin N Am 22:4, 633-57

Eccentric target sign:

Specific not sensitive

+ HIV patient with mental status change


FLAIR

DWI

ADC

+ Cryptococcus


Cryptococcus neoformans

Associated with HIV infections

Can affect immunocompetent

patients

Presents as

Meningitis

Meningoencephalitis

Cerebral vasculitis

Imaging may be normal.

+ Cryptococcus


Imaging patterns:

• Meningeal enhancement

• Basilar meningitis

Masses: cryptococcomas

Granulomas

Basal ganglia predominant

May enhance (immunocompetent)

Choroid plexus

Gelatinous exudate:

• Dilated perivascular spaces

• Pseudocysts

+ Image Gallery


T2 T1 post

DWI

ADC

FLAIR T1

+ Image gallery: C. gatti


Dilated VR spaces Cryptococcomas of choroid plexus


Tuberculous meningitis

Cryptococcus meningitis

Coccidioidal meningitis


+



+ 54 yo, aortic valve replacement, new headache

NECT CTA 5/10/2017 KRF CNS infxn

+ Conventional Angiogram

2 months prior Current

Right ICA injection 5/10/2017 KRF CNS infxn

+ Mycotic aneurysm

New peripheral (distal MCA)

aneurysm

Unusual location for saccular

aneurysm

Treatment is resection

* methicillin-sensitive staphylococcus aureus


+ Infectious vasculitis: S. pneumo meningitis

Initial T2 2 wks later


+ Septic emboli


+ Outline

Indications for imaging

CNS infections

Extra axial

Parenchymal



Thank you!

Kathleen Fink [email protected]

KRF CNS infxn 5/10/2017

kathleen r. fink, md virginia mason medical center · kathleen r. fink, md virginia mason medical...

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