الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم

Interpretation

in·ter·pre·ta·tion

DR.Tajuddin Malabarey

Associate professor

365-March 2011

Interpretation• Something that serves to explain or clarify:

Clarification, Explanation, Illumination, Illustration.

• The act or process of explaining the meaning of something.

Interpretation

Interpretation 1=Normal Radiological Anatomy 2= How to look at the images? (a) Where to look? Systematic approach (b) what look for: (i) abnomal opacty (ii) abnorma radiolucency (iii) distotion or displacement of a normal

structure

3= How to interpret the abnormality? (a) Recognizing the abnormality, (b) Describing it in generic terms, (C) Giving a specific diagnosis

• Normal radiological image of certain age and sex is a mental image that must be developed

Normal Radiological Anatomy

• By developing a systematic approch to examine the radiological image

• Advantages:• Minimizes the chance of missing an

abnormality• Makes complex images easier to read

with practice• Builds up a mental databank of what is

normal

How to build up a normal mental image

Normal VS, Abnormal

It is not possible to call an image abnormal if the normal appearance is not known!!

Bone is white

Calcium is white;

Acute hemorrhage is usually white

Brain parenchyma is light grey;

White matter is darker than grey matter

CSF is very dark grey;

Sulci, cisterns and ventricles

Air is black;

Nasal cavity, sinuses, mastoid air cells

White

Light Grey

Charcoal Grey

Black

In order to recognize the abnormal, you first need to know the appearance of the normal.

On non-contrast head CT:

T1 Characteristics

•Dark•CSF•Increased Water – edema, tumor, infarct, inflammation, infection, hemorrhage (hyperacute or chronic)•Low proton density, calcification•Flow Void

•Bright•Fat•Subacute hemorrhage•Melanin•Protein-rich Fluid•Slowly flowing blood•Gadolinium•Laminar necrosis of an infarct

•White matter brighter than Gray

Johnson,KA and Becker, JA. The Whole Brain Atlas. 1995-1999

T2 Characteristics•Dark

•Low Proton Density, calcification, fibrous tissue• Paramagnetic substances - deoxyhemoglobin, methemoglobin (intracellular), iron, hemosiderin, melanin •Protein-rich fluid•Flow Void

•Bright•Increased Water – edema, tumor, infarct, inflammation, infection, subdural collection•Methemoglobin (extracellular) in subacute hemorrhage

•Gray matter brighter than white

Johnson,KA and Becker, JA. The Whole Brain Atlas. 1995-1999

Interpretation• Learn Normal Radiological

Anatomy

• How to look at the images?

• How to interpret the abnormality?

How to look at the images?

• Where to look?Systematic approach

• What to look for? The documentary evidence of name and

age Technical factors Areas of interest (Normal anatomical

structures)

Patient Name

• What to look for?

3.Areas of interest (Normal anatomical structures)

Systematic Approach to reading a Head CT

I. Check Brain Parenchyma• Check grey/white differentiation• Gyri• Look for blood• Surgeons need to know . . . (size of hematoma, extent of

midline shift, herniation)

II. Check CSF spaces: Ventricles, Cisterns and Sulci• CSF spaces (ventricles and cisterns)

– size, symmetry, midline shift– herniation

• Subfalcine – cingulate gyrus crosses falx• Transtentorial – temporal lobe into tentorial notch • Cerebellar – cerebellum into foramen magnum

Systematic Approach to reading a Head CT (cont’d 2)

III. Check face and skull bones on bone windows– Do not confuse sutures with fracture especially in

pediatric patients

IV. Check “air spaces”– Sinuses– Nasal airway– Ear Canals and Mastoid air cells

What to look for? In CT HeadBrain tissue (windows)

Pre contrast Post contrast

Bone detail (window)

Frontal lobe

Midbrain

Cerebellum

RIGHT LEFT

Pre contrast Post contrastPre contrast Post contrast

Bone detailBone detail

Brain tissueBrain tissue

what look for: (i) abnomal opacty

(ii) abnorma radiolucency (iii) distotion or displacement of a normal structure

Frontal lobe

Midbrain

Cerebellum

RIGHT LEFT

Normal

abnomal opactyabnomal opacty

abnorma radiolucencyabnorma radiolucency

distotion or displacement of a normal structuredistotion or displacement of a normal structure

3= How to interpret the abnormality?

(a) Recognizing the abnormality,

(b) Describing it in generic terms,

(C) Giving a specific diagnosis

Patient’s A Head CT

• R frontoparietal subdural hematoma (6 mm)

• Midline marker• R temperoparietal epidural

hematoma (1.8 cm)• 6 mm leftward shift of

lateral ventricles• Right lateral ventricle• Left lateral ventricle• Effacement of R sulciBIDMC

Film findings:

Parenchymal Parenchymal HemorrhageHemorrhage

Subarachnoid Subarachnoid HemorrhageHemorrhage

Subdural Subdural HematomaHematoma

EpiduralEpidural

Patient B

• 57yr old woman

• History of migraines

• Presents with persistent headache– several months duration– different from her usual headache

Need to rule out intracranial abnormality

BIDMC PACS system

Frontal lobe

Midbrain

Cerebellum

RIGHT LEFT

Patient’s B Head CT (no contrast)

BIDMC PACS system

Frontal lobe

Midbrain

Cerebellum

RIGHT LEFTFilm Findings:• Spherical mass • Smooth margined• High attenuation• Slight mass effect• Located just

anterior to the Circle of Willis

• No acute hemorrhage, edema, infarct

Frontal lobe

Midbrain

Cerebellum

RIGHT LEFT

DDx: Cerebral mass

• Tumor

• Hematoma

• Abscess

• Arterio-venous malformation (AVM)

• Aneurysm

Patient’s B Head CT (with contrast)

BIDMC PACS system

RIGHT LEFT

BIDMC PACS system

Frontal lobe

cerebellum

Frontal lobe

cerebellum

RIGHT LEFT

2 brightly enhancing round lesions suggestive of cerebral aneurysms

Lets review the anatomy of the Circle of Willis

http://www.strokecenter.org/education/ais_vessels/ais048.html

• Communicating system of vessels that supplies blood to the brain

• Anterior portion fed by the internal carotid arteries

• Posterior portion fed by the vertebral arteries

Patients B Axial MR (T2 sequence)

BIDMC PACS system BIDMC PACS system

RIGHT LEFTRIGHT LEFT

T2 sequence: CSF is bright (“high signal”)

Round lesions with flow void confirmed

Menu of tests for evaluating suspected: Cerebral

aneurysm• Computed tomography (CT) + contrast

• Magnetic resonance imaging (MRI)

• Magnetic resonance angiograpy (MRA)

• Cerebral angiography

MRA - Circle of Willis

BIDMC PACS system

http://www.strokecenter.org/education/ais_vessels/ais048.html

b

Internal carotid artery aneurysms

asi

la

r

vertebral arteries

internalcarotid

internalcarotid

ACA

MCA

PCA

RIGHT LEFT

Our PatientAnatomic Diagram

Patient C

Patient’s C

Normal

Patient’s C

Normal

Patient’s C

Interpretation•Features of several diseases,

• trauma

•and non-trauma

CNS Trauma Imaging

SELLA SELLA TURCICATURCICA

CORONAL CORONAL SUTURESUTURE

GROOVE GROOVE FOR MCAFOR MCA

EXT.AUD EXT.AUD MEATUSMEATUS ORBITAL ORBITAL

GROOVEGROOVE

Normal Linear fracture

Epidural H Depressed fracture

Orbital Fracturesblow-out

NORMAL WATERS VIEWMedial/Inferior orbital wall blow-outMedial/Inferior orbital wall blow-out

Orbital Fracturesblow-outNORMAL WATERS VIEW Medial/Inferior orbital wall blow-outMedial/Inferior orbital wall blow-out

Axial CTCoronal CT

Medial/Inferior orbital wall Medial/Inferior orbital wall blow-outblow-out

Depressed right orbital floorDepressed right orbital floorOpacification of right Opacification of right maxillary sinusmaxillary sinusOpacification of right Opacification of right ethmoid sinusethmoid sinus

““Hanging tear drop”: Hanging tear drop”: herniation of orbital fat into herniation of orbital fat into maxillary sinus (not seenmaxillary sinus (not seen

here)here)

Orbital Fracturesblow-out

Interpretation

Non-trauma

Extra-axial vs Intra-axial

Meningioma Glioma

(external to pia) (beneath pia)

Supra-tentorial vs Infra-tentorial

Glioma Medulloblastoma

Nonenhanced computed tomography scan shows a hyperdense mass resulted in midline shift to the right aspect in the left frontal lobe

CECT shows a homogeneous enhancing mass located in the left frontal lobe.

DSA, Left external carotid artery injection shows early stain of the mass

DSA: Left external carotid artery shows delayed stain of the mass

Hydrocephalus versus Cerebral Atrophy

Definition

:Hydrocephalus is abnormal accumulation of intracranial fluid resulting from structural or functional block to normal flow of CSF,

cerebral atrophy is parenchymal volume loss

Hydrocephalus is abnormal accumulation of intracranial fluid

resulting from structural or functional block to normal flow of CSF,

cerebral atrophy is parenchymal volume loss

Agenesis of the corpus callosum

Patterns of edema

Edema: Increase in tissue water

CT - decreased density

MR - T1W - decreased signal

MR - T2W - increased signal

Patterns of edemaVasogenic

(intertitial)

white matter only

neoplasm

abscess

Cytogenic(intracellular)

both gray and white matter

infarction

Normal

Vaogenic oedema (tumor &inflamation) Cytotoxic oedema ( infarction)

White matter

White&gray matter

CONCLUSION KNOW YOUR Normal Radiological Anatomy

look for: (i) abnormal opacity (ii) abnormal radiolucency (iii) distortion or displacement of a normal structure

Interpret the abnormality: (a) Recognizing the abnormality, (b) Describing it in generic terms, (C) Giving a differential diagnosis

Give a specific diagnosis

KNOW your radiological terminology

BEST LUCK

HOPE THIS WAS

HELPFUL