Patterns of EnhancementJames G. Smirniotopoulos, M.D.

Professor of Radiology and NeurologyChairman, Department of Radiology Uniformed

Services University of the Health Sciences4301 Jones Bridge Road

Bethesda, MD 20814 USA

Voice: 301-295-3145FAX: 301-295-3893

Email: jsmirnio@usuhs.milVisit us on the WEB at: http://rad.usuhs.mil

DISCLAIMER

The opinions expressed herein are those of the author(s), and are not necessarily representative of the Uniformed Services University of the Health Sciences (USUHS), the Department of Defense (DOD); or the World Health Organization (WHO). Medicine is a constantly changing field, and medical information is subject to frequent correction and revision. Therefore the reader is entirely responsible for verifying the accuracy and relevance of the information contained herein. Portions copyright 1997-2000 James G. Smirniotopoulos, M.D.

CONTRAST ENHANCEMENT

•Vascularity

•Permeability

CONTRAST ENHANCEMENT

•Vascularity–Blood Volume–Blood Flow

•Permeability–Capillary

CONTRAST ENHANCEMENT

• Any change (increase or decrease) in signal (intensity, density, etc.) over the pre-injection (inhalation, etc.) or normal background pattern, that increases the conspicuity of a lesion or makes the anatomy more visible.

CONTRAST ENHANCEMENT

– Fill a cavity (BE, Cystogram, Myelogram)– Inject a Vessel (Angiogram, venogram,

bronchogram– Diffusion (from vessel) into Interstitium

CT w/ Iodine– MR w/Gadolinium– "Bodygram" on XU

CONTRAST ENHANCEMENT

• VASCULAR (intravascular) PHASE(Inc. Blood Flow/Hypervascular)AVM, MENINGIOMA, GBM, ETC.TRUE "LUXURY" PERFUSION HYPEREMIA (TRAUMATIC)

• INTERSTITIAL (extravascular) PHASE (Blood‑brain‑barrier breakdown)Acute inflammation (ms), Neoplasm, Abscess, "granulation" tissue, Ischemia, "luxury" perfusion,Contusion

CONTRAST ENHANCEMENT

Normal Tissue w/o BBB• DURA (falx and tentorium)• (ARACHNOID ?)• CHOROID PLEXUS• PINEAL GLAND (epiphysis)• PITUITARY GLAND (hypophysis)• CTZ (MEDULLA ‑ AREA POSTREMA)

("Circumventricular Organs")

Enhancement vs. Edema

ABNORMAL PERMEABILITY(ABBB)

EDEMA ENHANCEMENT

INCREASED VASCULARITY

CONTRAST ENHANCEMENT -

PhasesVASCULAR BBB

ANGIO(I‑) ++++ ‑

R‑N (Tc+) + (flow) + (static)

C.T. (I‑) + +++

MRI (Gd+) +/‑ +++

CONTRAST ENHANCEMENT

• Morphologic Patterns– HOMOGENEOUS (SOLID)– HETEROGENEOUS (non‑uniform)– RING (unilocular/multilocular)– SERPENTINE ("GYRIFORM")

CONTRAST ENHANCEMENT

• Location– SUPERFICIAL (CORTICAL/GYRAL)– GREY‑WHITE JUNCTION– DEEP WHITE MATTER– PERIVENTRICULAR, EPENDYMAL

CONTRAST ENHANCEMENT

Cortical/Gyriform– Cerebral Ischemia / Infarction– CSF or sub‑pial spread– Meningo‑encephalitis– S.A.H.– Leptomeningeal Malformation (SW)– Meningioangiomatosis (NF2)

CONTRAST ENHANCEMENT

• Ring LesionCircumferential or peripheral/marginalenhancement, surrounding a centralnon‑enhancing region. In turn, this isoften surrounded by a large area of "edema". May Be Unilocular OrMultilocular.

CONTRAST ENHANCEMENT

• Contrast leaks into interstitium from vessels without BBB

• Remains localized within millimeters of where it leaks out

• Not "simple diffusion" but rather "BULK FLOW" at a very slow rate

• (Glacier Not River)

CONTRAST ENHANCEMENT

Diffusion ExperimentSHARK TANK ‑ with volunteer• Flowing Water ‑ rapid movement by "bulk

flow”• Motionless Water ‑ Diffusion (simple

diffusion)• Jell-O, viscous fluid, DB or DT

slow movement by "bulk flow"

CONTRAST ENHANCEMENT

Ring LesionsM ‑ Metastasis, MSA ‑ Abscess (Also Cerebritis)G ‑ Glioblastoma, GranulomaI ‑ Infarct (Esp. Basal Ganglia)C ‑ Contusion (Rare)A ‑ AIDS (Toxo, Etc.)L ‑ Lymphoma (in Aids)

D ‑ Demyelination (Active)R ‑ Resolving Hematoma Radiation Change (Necrosis)

CONTRAST ENHANCEMENT

Ring Lesion Features For Infection• ORGANIZED ABSCESS

thin and uniform wall (3‑7mm.)smooth inner margin does not "fill in" on CT, MR?

• CEREBRITIS (infection w/o organization):variable wall (may be smooth) smooth/variable inner marginoften has "fill‑in" on DDD(w/o fluid level)

CONTRAST ENHANCEMENT-

Abscess• 2 ‑ 4 wks. for ORGANIZED WALL• 2 LAYERS• inner MESENCHYMAL (capillaries,fibroblasts,

collagen)• outer ASTROGLIAL (reactive astrocytes)• WALL facing GM is well formed 3‑5 mm• WALL FACING WM IS THINNER/WEAKER

(Daughter Abscess)Ventricular Spill ("pyocephalus")

CONTRAST ENHANCEMENT

Ring Lesion Features For NeoplasmNECROTIC NEOPLASM:• thick and irregular wall• shaggy inner margin (usually)• may "fill in" heterogeneously on DDDCYSTIC NEOPLASM:• thin wall +/‑ MURAL NODULE• PART OF WALL MAY NOT ENHANCE

– smooth inner margin– uniform fluid enhancement

or FLUID LEVEL

CONTRAST ENHANCEMENT-

HematomaEARLY: Hyperdense, round/oval

Homogeneous mass of RBC's Proportional mass effect for volume Edema "Halo", not spreading

LATER: Iso‑/Hypodense, smaller Reactive capillaries form outside Uniform rim of enhancement May see "vasogenic" edema

CONTRAST ENHANCEMENT- Post-

Operative• RESIDUAL TUMOR

– (left behind)• RECURRENT TUMOR

– (grew back)• INFECTION• NORMAL POSTOPERATIVE CHANGE

– (surgical trauma, healing)• RADIATION Tx.?

CONTRAST ENHANCEMENT - Surgical Change and/or Residual

Neoplasm?• Surgical Enhancement typically after 24‑48

hrs.(scan early!)may last for months

• In the Operative Bed (mixed w/ residual?) and along the Margins of Resection– thin and uniform in brain (CT/MR)

• LINEAR meningeal/dural enhancement on MR (not lumpy-bumpy)

• Small amts. of air, blood (non‑contrast)

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