Procedures Flashcards
- Gantry Angle For CT Brain is ______
- Is CT Brain Helical or Axial Scan? Why?
- What Causes Streak Artifacts in a CT Brain? How is this fixed/prevented?
- Parallel to Supraorbital Meante Line (SOML)
- Axial b/c Gantry can’t be tilted & scan in Helical
- Posterior Fossa typically has streak artifacts due to different attenuation between hard skull and soft brain tissue.
- Adjusted by using different slice thicknesses.
- Adjust by increasing kVp
- How is the Posterior Fossa scanned? Why?
- When would you scan a CT Brain in Helical?
- Brain Window Width & Level For:
- Soft Tissue ____ WW & ____ WL
- Posterior Fossa ____ WW & ____ WL
- Blood ____ WW & ____ WL
- 1.25mm thickness to help reduce beam hardening artifacts
- Reduce motion artifacts or 3D post processing is needed
- Brain Window Width & Level For:
- ST = 160 WW & 40 WL
- PF = 100 WW & 30 WL
- Blood = 200 WW & 60 WL
- What type of Window Width is needed for viewing CT Brain? Why?
- How will a hemorrhage appear from onset - 3 days?
- 4-10 days?
- 11 days - 6 months?
- Beyond 6 months? - Clinical Indications for Contrast in CT Brain?
- Narrow Width b/c of slight differences between gray & white matter of brain
- Onset -3 = Hyperdense
- 4-10 days = Hyperdense Center w/ hyper&hypodense surroundings
- 11 Days- 6mo = Isodense Center w/ Hyperdense surroundings
- 6mo+ = Hypodense - Infection, Neoplasm, Venous Malformation
CT BRAIN:
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Gantry to SOML
PREP= NONCON but if CON ~100ml
CLIN= w/o Hematoma, IHA, Infarction, Dementia, Hydrocephalus
- w/ = Infection or Neoplasm
SCAN= Below Skull Base - Above Vertex
ALG.= Soft Tissue & Bone
SLICE= Thin (2-5mm) For Skull Base Through Post. Fossa
- Thick (5mm+) For Post Fossa to Above Vertex
RFMT= SAG, COR, Protocol Dependent
CT FACIAL BONES
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine
PREP= NONCON
CLIN= Facial Trauma
SCAN= Frontal Sinus to below Mandible
ALG.= Soft Tissue & Bone
SLICE= 2mm - 3mm
RFMT= SAG, COR, 3D
CT ORBITS
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Gantry Parallel to IOML
PREP= NONCON, But if ~100ml
CLIN= w/o Trauma, FB
- w/ Mass, Infection, Inflammation
SCAN= Orbital Floors to Orbital Roofs
ALG.= Soft Tissue & Bone
SLICE= 2mm - 3mm
RFMT= COR & SAG
- Oblique maybe for Optic Nerve
CT SINUS’
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= SUPINE
PREP= NONCON, But If ~100ml
CLIN= w/o Sinusitis
- w/ Infection, Mass or Vascular Ab
SCAN= Maxillary & Ethmoidal Sinus through Sphenoid & Frontal
ALG.= Soft Tissue & Bone
SLICE= 2mm - 3mm
RFMT= COR & SAG
- When would Oblique Orbits be requested?
- Facial Bones may require what? (in regards to patient position)
- What reduces need for patient to be prone in CT Sinus’?
- Optic Nerve is ROI
- Open Mouth Scan & Closed Mouth Scan
- MPR removed need for prone or dropped head
- CTA of Brain images what?
- What are the Arteries of Interest in CTA Brain?
- What is typically done prior to a CTA Brain?
- What phase is CTA Brain scanned at? Why is this important?
- Arteries of Brain at peak opacification
- Basilar Artery, Middle Cerebral Artery, & Circle of Willis (COW)
- NONCON Brain CT
- Arterial Phase
- Specific Injection Rate of 4ml/s +
CTA BRAIN
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Antecubital IV
PREP= CON 60-80ml
CLIN= Cerebral Aneurysm, Arterial Stenosis, Malformation
SCAN= C2 to Top of Skull
ALG.= Soft Tissue
SLICE= 1mm-2mm
RFMT= COR, SAG, MIP, 3D
- What is typically done prior to a CT Perfusion Scan?
- What is a Perfusion scan evaluating?
- Goal of Perfusion? - 3 Key Measurements of Perfusion:
- NONCON Brain CT
- Evaluate blood flow in & out of brain tissue.
- Determine infarcted brain tissue vs viable brain tissue - Blood Volume, Blood Flow & Mean Transit Time
- Define:
- Cerebral Blood Volume
- Cerebral Blood Flow
- Mean Transit Time - Perfusion Contrast:
- Amount:
- Rate:
- Time: - What is crucial in perfusion images? Why?
- CBV= Quantity of blood in 100g tissue
- CBF= Quantity blood moves in 100g tissue in 60 seconds
- MTT= Average time takes blood pass through given area - 50 ml/s
- 5.0-7.0ml/s
- For 60 Seconds - Only ROI scanned
- Higher Dose b/c longer scan time
CT PERFUSION
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Antecubital IV
PREP= CON 50ml,
- Xenon / Xe per protocol
CLIN= Stroke, Vasoplasm, Temporary Occlusion
SCAN= Only ROI (Typically COW)
ALG.= Soft Tissue
SLICE= 3mm - 5mm
RFMT= COR, SAG, 3D, FLOW MAPS
- What type of scan is CT Neck scanned in?
- CT Neck patient positioning considerations?
- Why do you preform Valsalva & “eee” ?
- Helical
- Extend neck up
- lower shoulder much possible
- Valsalva or “eee” - Valsalva = Pyriform Sinus
- eee = Areyepiglottis & Pyriform
CT LARYNX
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Gantry Parallel Vocal Cords
PREP= CON 80-135ml @45-90sec delay
CLIN= Mass, Cyst, Infection, Vocal Cord Damage
SCAN= Mid Orbits To Clavicles
ALG.= Soft Tissue
SLICE= 1mm - 2mm
RFMT= COR & SAG
- How is the gantry positioned in CT Soft Tissue Neck? Why?
- What are typical patient instructions during CT Soft Tissue Neck? Why?
- What Organ/Anatomy is important consideration in CT STN & Why?
- Orbits to Hard Palet = Gantry parallel to hard palette
- Rest of scan = parallel to mandible body
- This prevents streak artifacts - Stop Swallowing & Breathe Softly
- Reduce patient motion - Thyroid Gland
- Hyperdense / important consideration w. contrast
CT SOFT TISSUE NECK
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine
PREP= CON 80-125ml @ 45-90sec delay
CLIN= Mass, Cyst, Infection, Swollen Glands
SCAN= Mid Orbits to Clavicles
ALG.= Soft Tissue
SLICE= 2mm - 3 mm
RFMT= SAG & COR
CTA NECK
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Antecubital Right Arm
PREP= CON 60-80ml @SP 15-18sec
CLIN= Aneurysm, Vascular Injury, Occlusion, Arterial Stenosis
SCAN= Skull Base to Aortic Arch
ALG.= Soft Tissue
SLICE= 1 - 1.5 mm
RFMT= COR, SAG & MIP
- What phase is CTA Neck scanned?
- Why is this important? - What’s done before CTA Neck?
- Contrast injection rate, amount & typical delay for CTA Neck?
- Arterial enhancement of carotid arteries
- Important for injection rate 4.0+ and time being boils tracked 13-18sec - NONCON Neck
- 60-80ml @ 4.0ml/s @ Bolus Tracking but typically 13-18 sec empiric delay
- Where is the IV best placed for CTA Neck? Why?
- Describe C-Spine Anatomy
- Where does the spinal cord begin & end? What is the name of it?
- Right Antecubital
- Reduce streak artifact from contrast entering vasculatures - Between C1 & C2 there’s no intervertebral disc space
- C2 - C7 there is - Medulla of brain to level of L1
- Tapers off into bundle nerves called Cauda Equina
- What does intervertebral disc consist of?
- What is
- Spondylosis
- Spondylolysis
- Spondylothesis - What is spinal Stenosis?
- Nucleus Pulpous - Center of disc
- Anulus Fibrosis - Outer portion of disc - Losis = Hypertophy of
- Lolysis = Damage to interarticularis
- Lothesis = Superior body slips over inferior - Narrowing of spinal cord
CT CERVICAL SPINE
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Head First,
PREP= NONCON, But if 80-100ml @1-3ml/s (Portal Venous Phase)
CLIN= Herniated Disc, Trauma, Lesion, Degeneration, Infection, Post Op
SCAN= Skull Base to T1
ALG.= Soft Tissue & Bone Window
SLICE= .5 mm - 2.0 mm
RFMT= COR, SAG, 3D
- Typical rate of contrast for CT Spine studies?
- What Phase? - What is HNP?
- What are clinical indications for CT Spines?
- 1-3ml/s
- Portal Venous Phase - Herniated Nucleus Propos. (Herniated disc / nucleus protruding)
- HNP, Trauma, Fracture, Post-Op, Degenerative Diseases (Spondies), Lesion, Infections
CT THORACIC SPINE
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Arms Over Head
PREP= NONCON but if 80-100ml @1-3ml/s @ Portal Venous
CLIN= Trauma, Fx, Degenerative, Post Op
SCAN= C7 to L1
ALG.= Soft Tissue & Bone Window
SLICE= 2mm - 5mm
RFMT= COR, SAG, 3D
CT LUMBAR SPINE
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Arms Over Head, Knees Bent
PREP= NONCON but if 80-100ml @1-3ml/s @ Portal Venous
CLIN= Trauma, Fx, Degenerative, Post Op
SCAN= T12 Through L5
ALG.= Soft Tissue & Bone Window
SLICE= 2mm - 5mm
RFMT= COR, SAG, 3D
- What is different about CT Lumbar positioning vs C & T Spine?
2 Why are Breath Holds used in CT Chest exams?
- Common site for Metastesses?
- C & T =. Head First
- L = Feet First & Cushion for bent knees to relieve low back pain
T & L = Arms Raised - Reduce motion artifacts
- Adrenal Glands
- How is a CT Chest typically scanned?
- Why? - Contrast rate & amount for CT Chest?
- Cardiac Exams Ideal HR?
- Inferior to Superior to reduce contrast artifacts as it is injected
- 70-120 ml @ 2-4ml/s
- Below 65 BPM
CT CHEST
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Arms Raised
PREP= CON 70-120ml @ 2-4ml/s,
Breath Holds
CLIN= Mass, Infection, Emphysema, Congenital Thoracic Cond. Abnormal XRays
SCAN= Above Apices to below lung base / diaphragm
ALG.= Soft Tissue & Lung Window
SLICE= 2mm - 5mm
RFMT= COR & SAG
CT CHEST (HIGH RESOLUTION)
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine or Prone, Arms Raised
PREP= NONCON, Breathhold, Insp & Exp
CLIN= Asthma, COPD, Cystic Fibrosis, Emphysema, Bronchitis
SCAN= Above Apices through Lung Bases
ALG.= Soft Tissue & Lung Window
SLICE= .5mm - 2mm
RFMT= COR, SAG, MIP, MinIP
- What are patient instructions in High Resolution CT Chest?
- Why? - How is a CT Chest High Res. Scanned?
- What are the Recons in & Why? - What is patient position in CT Chest High Res?
- Why?
- Inspiration & Expiration
- Displace air trapped in patients - Axially w/ Thin Slices (.5-2mm)
- Recon in 10-15mm to better demonstrate interstanial lung disease - Supine & Prone
- Demonstrate Edematous Changes
- Describe Steps of Blood Flow Through Heart.
- Which Side is Oxygenated?
- Superior Vena Cava or Inferior Vena Cava -> 2. Right Atrium -> Tricuspid Valve -> Right Ventricle -> Pulmonary Artery -> Lungs -> Left Atrium -> Mitrial/Bicuspid Valve -> Left Ventricle -> Aorta -> Rest of Body
- LEFT SIDE = Oxygenated (LOX)
RIGHT SIDE = Deoxygenated
- What is commonly used in CT Cardiac Exams?
- What branches off of the RIGHT Coronary Artery?
How Remember - What about the Left?
How Remember
1 ECG Gating
- Conus Artery, Sinus Node Artery, R. Atrial & Ventricle Branches, Posterior Descending Artery
**RIGHT C.A.P = Conus, Sinus, Posterior - Left Anterior Descending Artery & Left Circumflex Artery
** LEFT LAC = Anterior & Circumflex
- What medications are used in CT Cardiacs?
- Why? - What advantages do newer CT Scanners have?
- Why are they important? - What phase of Cardiac Cycle is scanned in CT Cardiacs?
- Why?
- Beta Blockers = Lower HR
- Nitroglycerin = Dilate Vessels - Higher Temporal & Spatial Resolution
Temporal = Clearer images of object in motion
Spatial = Differentiation between structures close together - Diastolic / Rest
- Eliminate Cardiac Motion
- Temporal Resolution =
- Spatial Resolution = - What helps reduce patient dose in Cardiac Exams?
- When are images acquired for Cardiacs?
- What % ECG Interval is used for Cardiac Scan?
- Temporal = Ability produce clearer images of objects in Motion
- Spatial = Allows differentiation between structures close together - Radiation shut off when not in diastolic phase of cycle
- Images acquire through whole cycle, only portion is used for reconstruction
- 55-75% of R-R Interval
CT CARDIAC (Coronary Arteries)
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Antecub IV, ECG
PREP= CON 80-100ml @ 4-7ml/s, Breathholds & Meds
CLIN= Cardiac Abnorm, Calcification, Morphology, Myocardial Perfusion
SCAN= Carina through Apex Heart
ALG.= Soft Tissue
SLICE= 0.4mm - 0.7mm
RFMT= COR, SAG, MIP, 3D, VR, SSD
CT CARDIAC - Calcium Score
Patient:
Prep:
Clinical Ind: (w & w/o)
Scan Range:
Algorithm:
Slice Thickness:
Reformats:
PT= Supine, Arms Raised, ECG
PREP= NONCON
CLIN= Atherosclerotic Disease
SCAN= Carina through Apex Heart
ALG.= Soft Tissue
SLICE= 2mm - 3mm
RFMT= COR, SAG, 3D
- CT Calcium Score evaluates what?
- Why does Calcium Score use ECG?
- Is CT Calcium Score High Dose or Low Dose?
- Calcification of Coronary Arteries
- Monitor Cardiac Cycle for Diastolic phase
- reduce patient dose & limit motion artifacts - Lower Rad Dose
- What defines “Calcification” of Coronary Arteries?
- What’s the Calcium Score Measurement System Called?
- What Are The Ranges for Calcification?
- 1mm^2 with HU above 130
- Agatston Scoring System
- 1-10 Minimal
11-100 Mild
101-400 Moderate
400+ Excessive
- What Breathing Is Used for CT Pulmonary Angiography?
- Why? - How is CT Pulmonary Angiography scanned?
- Why? - Goal of CT Pulmonary Angiography?
- How is it done? - Why is Saline Flush after CTA Pulm good?
- Shallow Breathing or Hold Breath
Shallow Better b/c hold can trap non-opacified blood in arteries and dilute contrast - Caudicranial
- Reduce motion artifacts from patient breathing & reduce artifacts from contrast as it’s being administered - Image Pulmonary Arteries at Peak Opacification
- By Bolus Tracking and Rate of 4.0+ - Saline Flush after to help reduce streak artifacts in Superior Vena Cava