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‫بسم هللا الرحمن الرحيم‬
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 Anatomy
• Normal radiological image
of certain age and sex is a
mental image that must be
developed
How to build
up a normal mental image
• 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
Normal VS, Abnormal
It is not possible to call an
image abnormal if the
normal appearance is not
known!!
In order to recognize the abnormal, you first need to
know the appearance of the normal.
On non-contrast head CT:
White
Bone is white
Calcium is white;
Acute hemorrhage is usually white
Light Grey
Brain parenchyma is light grey;
White matter is darker than grey matter
Charcoal
Grey
CSF is very dark grey;
Sulci, cisterns and ventricles
Black
Air is black;
Nasal cavity, sinuses, mastoid air cells
T1 Characteristics
•Dark
•CSF
•Increased Water – edema,
tumor, infarct, inflammation,
infection, hemorrhage
(hyperacute or chronic)
•Low proton density,
calcification
•Flow Void
Johnson,KA and Becker, JA. The Whole Brain Atlas. 1995-1999
•Bright
•Fat
•Subacute hemorrhage
•Melanin
•Protein-rich Fluid
•Slowly flowing blood
•Gadolinium
•Laminar necrosis of an infarct
•White matter brighter than Gray
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
Johnson,KA and Becker, JA. The Whole Brain Atlas. 1995-1999
•Gray matter brighter than white
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 Head
Brain tissue (windows)
Pre contrast
Post contrast
Bone detail (window)
Brain tissue
RIGHT
LEFT
Frontal lobe
Bone detail
Midbrain
Pre contrast
Cerebellum
Post contrast
what look for:
Normal
(i) abnomal opacty
(ii) abnorma radiolucency
(iii) distotion or displacement of a normal stru
distotion or displacement of a normal structure
abnorma radiolucency
RIGHT
LEFT
Frontal lobe
abnomal opacty
Midbrain
Cerebellum
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
Film findings:
BIDMC
• 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 sulci
Epidural
Subarachnoid
Hemorrhage
Subdural
Hematoma
Parenchymal
Hemorrhage
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
RIGHT
LEFT
Frontal lobe
Midbrain
Cerebellum
BIDMC PACS system
Patient’s B Head CT (no contrast)
Film Findings:
• Spherical mass
• Smooth
margined
• High attenuation
• Slight mass
effect
• Located just
anterior to the
Circle of Willis
RIGHT
LEFT
Frontal lobe
Midbrain
Cerebellum
•
No acute hemorrhage,
edema, infarct
BIDMC PACS system
RIGHT
LEFT
Frontal lobe
Midbrain
Cerebellum
DDx: Cerebral mass
•
•
•
•
•
Tumor
Hematoma
Abscess
Arterio-venous malformation (AVM)
Aneurysm
Patient’s B Head CT (with
contrast)
RIGHT
LEFT
Frontal lobe
RIGHT
LEFT
Frontal lobe
cerebellum
cerebellum
BIDMC PACS system
2 brightly enhancing round lesions
suggestive of cerebral aneurysms
BIDMC PACS system
Lets review the anatomy of the
Circle of Willis
• 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
http://www.strokecenter.org/education/ais_vessels/ais048.html
Patients B Axial MR (T2
sequence)
T2 sequence: CSF is bright (“high signal”)
RIGHT
LEFT
RIGHT
BIDMC PACS system
BIDMC PACS system
Round lesions with flow void confirmed
LEFT
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
Our Patient
Anatomic Diagram
RIGHT
LEFT
ACA
MCA
a
r
l
b
a
s
i
PCA
http://www.strokecenter.org/education/ais_vessels/ais048.html
internal
carotid
internal
carotid
vertebral
arteries
BIDMC PACS system
Internal carotid artery
aneurysms
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
GROOVE
FOR MCA
CORONAL
SUTURE
SELLA
TURCICA
EXT.AUD
MEATUS
Normal
Epidural H
ORBITAL
GROOVE
Linear fracture
Depressed fracture
Orbital Fracturesblow-out
NORMAL WATERS VIEW
Medial/Inferior orbital wall blow-out
Orbital
Fracturesblow-out
NORMAL WATERS VIEW
Medial/Inferior orbital wall blow-out
Axial CT
Coronal CT
Orbital Fracturesblow-out
Medial/Inferior orbital wall blow-out
Depressed right orbital floor
Opacification of right maxillary
sinus
Opacification of right ethmoid
sinus
“Hanging tear drop”: herniation of
orbital fat into maxillary sinus (not
seen here)
Interpretation
Non-trauma
Extra-axial vs Intra-axial
(external to pia)
Meningioma
(beneath pia)
Glioma
Supra-tentorial
Glioma
vs
Infra-tentorial
Medulloblastoma
Nonenhanced
computed tomography
scan shows a
hyperdense mass
resulted in midline shift
to the right aspect in
the left frontal lobe
DSA, Left external carotid artery
shows early stain of the mass
CECT shows a
homogeneous
enhancing mass
located in the left
frontal lobe.
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 edema
Vasogenic
(intertitial)
Cytogenic
Normal
white matter only
neoplasm
abscess
(intracellular)
both gray and
white matter
infarction
White&gray matter
Vaogenic oedema (tumor &inflamation)
White matter
Cytotoxic oedema ( infarction
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