Imaging Procedures Flashcards
Gray / white matter Window
100 / 35
Hemorrhage / hematoma Window
150 / 75
Acute ischemia Window
25 / 35
Brain CTA Landmark
C2 through at least 1 cm above dorsum sella
Brain CTA Scan delay (when BT is not used)
12 - 20 sec
Acute Stroke Protocol
1) Precontrast head CT
2) CTA of the brain and carotid arteries
3) CT perfusion (CTP) imaging
Cerebral blood volume (CBV)
4 - 5 mL/100g
Cerebral blood flow (CBF)
50 - 60 mL/100g/min
Mean transit time (MTT)
Varies
CBF Formula
CBV / MTT
Mathematical technique for generation of perfusion maps
Deconvolution
Soft tissue neck Landmark
Superior orbital rim through lung apex
Larynx Landmark
Just above hyoid through cricoid cartilage
Soft tissue neck Scan delay
30 - 60 sec
Carotid CTA Landmark
Aortic arch through skull base
For COW, through at least 1 cm above dorsum sella
Carotid CTA Scan delay (when BT is not used)
15 - 18 sec
CTPA Scan delay (when BT is not used)
20 - 25 sec
CAC Score
1 to 10: Minimal
11 to 100: Mild
101 to 400: Moderate
>400: Extensive
Main branches of RCA
- Conus artery
- Sinus node artery
- Right atrial branches
- Right ventricular branches
- Posterior descending artery (PDA) aka posterior interventricular artery (PIV)
Main branches of LCA
- Left anterior descending artery (LAD)
- Left circumflex artery (LCX)
CAC Landmark
Aortic arch through cardiac base
CCTA Landmark
Carina through base of heart
CTA Aorta Landmark
Base of neck through celiac trunk
May extend superiorly to include carotid arteries or inferiorly through bifurcation and iliac arteries
Right arm
Carotid CTA, CTA Aorta
“Triple rule-out” MDCT Procedure
- CCTA for coronary artery disease
- CTA of the aorta for aneurysm
- CTA of the pulmonary arteries for embolism
CT density of normal hepatic parenchyma
45 to 65 HU
CT density of Spleen
about 10 HU less than liver
CT density Adrenal glands
25 to 40 HU
Example of Liver CT
1) Non con
2) Early arterial phase
3) Arterial phase
3) Portal venous phase
4) Delayed phase
Preferred timing for Spleen CT
Portal venous phase (60-70 sec), more homogeneous
Example of Pancreas CT
Water as oral contrast
1) Non con
2) Arterial phase
3) Pancreatic (delayed arterial) phase
4) Venous phase
Example of Adrenal glands CT
1) Non con
2) Portal venous phase
3) Delayed phase
Sheath of connective tissue that enveloped and supports kidneys
Gerota’s fascia
Epithelial lining for urinary tract
Urothelium
Genitourinary system Landmark
Above kidneys through base of bladder
May include above diaphragm
Example of Kidney and Urinary tract CT
Water or positive oral contrast
1) Non con
2) Arterial phase
3) Corticomedullary (delayed arterial) phase
4) Nephrographic phase
5) Excretory phase
GI system Landmark
Above diaphragm through pubis symphysis
May begin higher for esophageal pathology
Duodenum is suspended from the diaphragm by:
Ligament of Treitz
CTA Aorta (Body) Landmark
Above the arch through common iliac arteries
Bowel cleansing agents
Polyethylene glycol and Magnesium citrate
Spinal cord tapers into the:
Conus medullaris
Nerve bundle extending inferiorly from the spinal cord
Cauda equina
Primary goal of CTP
Identify and differentiate infarct core and penumbra (evaluation of acute stroke)
Uses water for oral contrast
- Pancreas
- Biliary
- Kidneys and urinary tract (positive contrast may be used)
- CTA Aorta (Body)
Peripheral CTA (Runoff) Landmark
Just below diaphragm to below ankles
FDG dose
10 - 15 millicuries (mCi)
Least heart motion occurs from approximately:
55 - 77% of the R-R interval
Peritoneum
- Stomach
- Small bowel (only part of duodenum)
- Transverse colon
- Liver and gallbladder
- Spleen
- Ovaries
Retroperitoneum
- Duodenum
- Pancreas
- Adrenal glands
- Kidneys, ureter, and bladder
- Aorta and inferior vena cava
- Prostate
- Uterus
Gallbladder and biliary tree Phases
Dual phase
- Arterial
- Portal venous
Ileus
Area of intestine that has lost normal contractile motion, resulting in obstruction
Abdominal aorta divides into right and left common iliac arteries at level of:
L4
CT Enterography, CT Enteroclysis (if applicable) Scan delay
45 - 50 sec
Early portal venous phase
Common iliac artery bifurcates at level of ______ into internal and external iliac arteries
L5 to S1
Glucose level before injection of FDG should be below:
150 mg/dL
Simple cyst HU
0 - 20 HU
Infarct core CBV
Less than 2.5 mL/100g
Hyperdense cyst HU
25 - 90 HU
Maxium dosage of IV contrast
2 mL per kg of body weight
In CAC areas of calcium have HU above:
130
Technical parameter controlling CT system’s temporal resolution
Gantry rotation time
Typical delay for GI system
Portal venous phase
Mesentric vasculature dual phase
Arterial and Portal venous phases
Colonoscopy Window
1600 / -400 (similar to lung)
Typical delay for Spine (if needed)
Portal venous phase
Delay for spine to assess vertebral arteries
Arterial or Dual phase