Mid Term Revision

Imaging Procedure 3

Dr Mohamed El Safwany, MD.

GOALS OF CT

• MINIMAL SUPERIMPOSITION

• IMAGE CONTRAST IMPROVEMENT

• SMALL TISSUE DIFFERENCE RECORDING

CT MAIN SYSTEMS

• IMAGING SYSTEM

• COMPUTER SYSTEM

• DISPLAY, RECORDING, STORAGE SYSTEM

• DATA ACQUISITION SYSTEM

COORDINATE SYSTEM IN CT

X

COORDINATE SYSTEM IN CT

Y

COORDINATE SYSTEM IN CT

Z

COORDINATE SYSTEM IN CT

ISO-CENTER

PATIENT ORIENTATION• HEAD FIRST • FEET FIRST

Computed tomography

Soft-tissue

Bone window

Computed tomography

• Unit controls:– Scanogram AP – Gantry tilt 0º– Slice thickness 7mm– Slice gap 9mm– Soft-tissue (Mediastinal)

window– Lung window

Computed tomography

Mediastinal window Lung window

Computed tomography

Computed tomography

• Positioning:– Supine and feet first – Arms above the head– The knees flexed 30º

• Parameters:– Starting at xiphoid process – Ending at the level of hip

joint – Respiration suspended in

expiration

Computed tomography

Unit controls • Gantry tilt: 0º. • Lateral scout view.• Gantry tilt: • parallel to the disc space • Slice thickness:

– 3mm

Computed tomography

air ---1000

fat---70

Pure water 0

Csf+8

White matter+30

Gray matter+45

blood+70

Bone/cacification+1000

MCA INFARCT

ACA INFARCT

Old infarct

H’gic infarct

CSF Production

• Produced in choroid plexus in the lateral ventricles Foramen of Monroe IIIrd Ventricle Acqueduct of Sylvius IVth Ventricle Lushka/Magendie

• 0.5-1 cc/min• Adult CSF volume is approx. 150 cc’s.• Adult CSF production is approx. 500-700 cc’s

per day.

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B is for Blood

• 1st decision: Is blood present?

• 2nd decision: If so, where is it?

• 3rd decision: If so, what effect is it having?

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Subdural Hematoma

• Typically falx or sickle-shaped.• Crosses sutures, but does not

cross midline.• Acute subdural is a marker for

severe head injury. (Mortality approaches 80%)

• Chronic subdural usually slow venous bleed and well tolerated.

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Andrew D. Perron, MD, FACEP

CT ScanCT Scan

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Intraventricular/Intraparenchymal Hemorrhage

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CT ScanCT Scan

Andrew D. Perron, MD, FACEP30

FRONTAL SINUS

CT SINUS AXIAL

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LENS OF EYE

RETRO ORBITALFAT

ETHMOIDSINUS

MEDIAL RECTUS MUSCLE

LATERAL RECTUSMUSCLE

CT SINUS AXIAL

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CT SINUS CORONAL VIEW

MAXILLARY SINUS

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NASAL SEPTUM

ORBIT

AXIAL CT

RETRORBITAL FAT

MEDIAL RECTUS LENS OF EYE LATERAL

RECTUS

OPTIC NERVE

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ARTERIOGRAM CAROTIDSYPHON

OCCIPITALARTERY

INTERNAL CAROTID ARTERY

EXTERNAL CAROTID ARTERY

COMMON CAROTIDARTERY

MAXILLARYARTERY

MIDDLE CEREBRAL

ARTERY

ANTERIOR CEREBRALARTERY

FACIALARTERY

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ANATOMYThe pulmonary arteries carry blood from the heart to the lungs.

They are the only arteries that carry deoxygenated blood.

INDICATION

Pulmonary embolism

Aortic dissection

Aortic overloading

Left ventricular stress

Teratology of Fallot

CONTRAST DOSAGE

1.2ml /kg (body weight) of non-ionic iodinated contrast

medium is injected intravenously into the patient using a

pressure injector.

Rate of injection being 4-5 ml /sec

Pressure 325 ppm

PATIENT POSITIONING

Proper breath hold instructions should be given

Ensure the patient connected IV lines, are long enough to

allow full travel of the couch without being pulled or entangled

while undergoing a CT

It is a software, that allows real-time monitoring of IV

Contrast enhancement in the area of interest.

SMART PREP TECHNIQUE

Good Luck