Aaron Grossberg
2012
• Increased blood flow
– Intravascular
– Rapidly appears after
contrast administration
• Capillary leak
– Extravascular/interstitial
– BBB normally
impermeable to contrast
– Slow appearing
• Often 10-15 min after
administration
• Increased blood flow
– Neovascularity
• Tumor
• Granulation tissue capsule
– Inflammation
– Reperfusion (post-ischemia)
• Capillary leak
–
–
–
–
–
–
Inflammation
Trauma
Post surgical changes
Granulomatous disease
Ischemia
Multiple sclerosis
1.
Herpes simplex encephalitis
-
extravascular/capillary leak = inflammation
Follows olfactory pathways from nasal cavity to brain
-
Medial temporal lobe
Uncus
Cingulate gyrus
Gadolinium – enhanced T1
Smirniotopolous et al. Radiographics. 2009
2.
Cerebral infarction (acute)
-
extravascular/capillary leak = endothelial damage
Increased blood flow
-
-
Hyperemia 2º to elevated CO2 after tissue injury
Wedge-shaped
Smirniotopolous et al. Radiographics. 2009
3.
Cerebral infarction (several weeks later)
-
Vascular hypertrophy = Increased blood flow
-
-
Fades by 4 weeks – 4 months after event
Necessary to repair/remove necrotic tissue
Only in reperfused tissue
4+ weeks
Smirniotopolous et al. Radiographics. 2009
Metastatic malignancies
Well-circumscribed
< 2 cm in diameter
Grey matter-white matter junction – most common
–
–
–
•
Primary tumors usually deeper
Usually cause symptoms, even when small
–
•
Due to location of lesions
CT scan
metastatic
melanoma
Gadolinium-enhanced
T1-weighted MR
metastatic
breast cancer
Smirniotopolous et al. Radiographics. 2009
Enhancing Ring
hyperemia
- inflammation
neovascularity
- tumor
capillary leak
- inflammation
** can be due to any ring-enhancing process
Center
hypoattenuating
- necrosis (tumor/abscess)
- pus (abscess)
- fluid (low grade tumor/cyst)
isoattenuating
- normal tissue (demyelinating disease)
Gadolinium-enhanced
T1-weighted MR
metastatic breast cancer
- subcortical/cortical
- well-circumscribed
- small ( < 2 cm)
Smirniotopolous et al. Radiographics. 2009
Enhancing Ring (T1-weighted MRI)
neovascular
thick - wall > 10 mm
irregular
Necrotic Center (T1-weighted MRI)
Crown of vasogenic edema (T2-weighted MRI)
Mass effect
Smirniotopolous et al. Radiographics. 2009
Gadolinium-enhanced
T2-weighted MR
Gadolinium-enhanced
T1-weighted MR
Enhancing Ring (T1-weighted MRI)
thinner than high grade
may appear incomplete
- part of ring is neoplastic, part is gliotic (nonenhancing)
mural nodule
DDx:
Pilocytic astrocytoma (cerebellum)
Hemangioblastoma (cerebellum)
Ganglioglioma
Pleomorphic xanthoastrocytoma
“Cystic” fluid-filled Center (T1-weighted MRI)
- not true cyst
-“cyst” w/ nodule appearance
Mural nodule
Smirniotopolous et al. Radiographics. 2009
Non-enhanced
T1-weighted MR
Gadolinium-enhanced
T1-weighted MR
Enhancing Ring (contrast T1-weighted MRI)
thin-walled (< 10 mm) – better evaluated on T2-weighted image
Non-enhancing Center (contrast T1)
- In abscess, center will be hypoattenuated due to
pus accumulation
- In cerebritis, center may fill in with contrast over
20-40 minutes
Perilesional vasogenic edema (contrast T2)
Restricted diffusion (diffusion-weighted)
- hyperintense
Gadolinium-enhanced
T2-weighted MR
Gadolinium-enhanced
T1-weighted MR
contrast CT
diffusion-weighted MR
Smirniotopolous et al. Radiographics. 2009
Gadolinium-enhanced
T2-weighted MR
T1-weighted MR
Enhancing Ring (contrast T1-weighted)
faint ring enhancement
perivascular, not intravascular
often appears “incomplete”
Isoattenuated Center (T1-weighted)
- no necrosis
No perilesional vasogenic edema (T2 –weighted)
Smirniotopolous et al. Radiographics. 2009
**If MS is suspected,
MRI of spinal cord may show add’l lesions
Enhancing rim
complete v. incomplete?
complete
incomplete
Center attenuation
hypo v. iso?
Thick & irregular rim
or thin & smooth rim?
thin & smooth
thick & irregular
single deep lesion or
multiple superficial?
multiple
superficial
metastatic
malignancy
single deep
high grade glioma
(GBM)
iso
mural nodule?
no
hypo
yes
Demyelination
(multiple sclerosis)
abscess/cerebritis
cystic neoplasm
(low grade glioma)
Glioblastoma multiforme
thick-walled
irregular internal ring
necrotic, heterogeneous center
abscess
thin-walled
smooth internal ring
homogeneous, hypoattenuating center
Multiple sclerosis
incomplete ring
isoattenuating center
No vasogenic edema
pilocytic astrocytoma
complete v. incomplete ring
hypoattenuating, fluid-filled center
mural nodule
THICK PERIVENTRICULAR ENHANCEMENT
* Neoplastic

primary CNS lymphoma
- homogenous “lamb’s wool” on contrast-enhanced imaging

high grade glial tumor
¤ metastatic lymphoma often involves cortex or
meninges
THIN PERIVENTRICULAR
ENHANCEMENT

thin enhancement (< 2 mm) along ventricle
margin
* Infectious ependymitis/ventriculitis
- often CMV in
immunocompromised patients
Smirniotopolous et al. Radiographics. 2009
MRI
Non-enhanced
CT
enhanced
Gadolinium-enhanced, T1-weighted
THICK PERIVENTRICULAR ENHANCEMENT
THIN PERIVENTRICULAR ENHANCEMENT
Primary CNS lymphoma in adult patient with AIDS
CMV ependymitis
Smirniotopolous et al. Radiographics. 2009
1.
2.
3.
Dural vs. Pial
- Dura (pachymeningeal) – along
surface of skull
- Pia (leptomeningeal) – follows sulci &
subarachnoid spaces
Linear vs. curvilinear
Associated with mass/nodule?
Remember:
Thin Dural enhancement normal on CT
Very vascular
No BBB in dura mater
Dural
Pial
Dura hypo-intense on T1
Thin linear enhancement with contrast
Smirniotopolous et al. Radiographics. 2009
Gadolinium-enhanced T1
Intracranial hypotension
- increased fluid shifts
- increased venous capacitance
Gadolinium-enhanced T1
Meningioma
- enhancing hypervascular tumor
- enhancing dural “tail”
- vasocongestion
- interstitial edema
Smirniotopolous et al. Radiographics. 2009
Gadolinium-enhanced T1
Bacterial meningitis
- thin, linear enhancement
- capillary leak
- cytokines & bacterial
glycoproteins
- Fungal meningits may produce thick,
lumpy, or nodular enhancement
Gadolinium-enhanced T1
Contrast-enhanced CT
Carcinomatous meningitis
- Spread of tumor through subarachnoid
space
- May still appear thin and linear
- capillary leak
- cytokines & tumor products
Smirniotopolous et al. Radiographics. 2009
FLAIR
Gadolinium-enhanced T1
Also seen in CNS granulomatous disease:
Sarcoid
TB/fungus
Wegener granulomatosis
Luetic gummas
Rheumatoid nodules
**All typically involve basilar meninges,
Sparing the convexities
Metastatic dural disease
- Enhancement of sulci (pial) and inner margin of skull (dural)
- Most commonly secondary to breast or prostate cancer; can be
lymphoma, as well
- lack of BBB predisposes to metastatic seeding
Smirniotopolous et al. Radiographics. 2009