Ch 3 Flashcards
What disease is not easily diagnosed in a CT Brain scan? What may it appear as?
Alzheimer’s disease is not easily diagnosed w/CT brain. May show enlargement of temporal horns.
What is the injection rate and delay in a CTA Brain for the Circle of Willis?
3-4mL/s, 12-20s delay after injection
What does CT Perfusion evaluate? What is the primary indication?
Evaluates cerebral perfusion w/iodine through vascular structures in brain; acute stroke = primary indication
Mean transit time
Average time (in seconds) for blood to pass through area of brain tissue (distance travelled between arterial inflow and venous outflow)
Where is cerebrospinal fluid secreted from?
Choroid plexuses in each of the four ventricles
Central volume principle formula
Cerebral blood flow (CBF) = cerebral blood volume (CBV) / mean transit time (MTT)
What does reduced CBF indicate?
Ischemia due to stroke or other brain abnormalities
What’s the best way to reduce contrast-induced nephrotoxicity?
Adequate hydration
Best scout plane for neck
Lateral
What breathing instructions are used for an HRCT chest?
Full expiration
What does an HRCT chest demonstrate?
Air trapping from suspected small airway diseases (COPD and emphysema)
What is required in CTA PE acquisition?
Peak enhancement of pulmonary arteries, thin sections (0.5-1.25), cauducephalad acquisition w/saline flush after contrast, 80-150mL low- or iso-osmolar contrast
Why do CTVs of lower extremities follow CTAs for PE?
For deep vein thrombosis (blood clots within distal blood vessels), common in popliteal and femoral veins
MDCT cardiac exams for coronary artery calcification (CAC) quantification:
Areas of calcium are identified as greater thab 1mm2 in area with 130+ HU
Branches of RT coronary artery
RT posterior descending artery
Branches of LT coronary artery
LT anterior descending and LT circumflex artery
Blooming definition
Potential overestimation of vessel calcification due to partial volume effect (exaggeration of calcification due to partial volume effect)
In cardiac MDCT studies, blooming can be mitigated with:
Increase in spatial resolution and appropriate window setting (1500HU) to reduce appearance of artifact
Glomerulus definition and entrance/exit of blood and waste
Nephron responsible for filtering unwanted substances from blood plasma; Blood enters through afferent arteriole, exits efferent arteriole; Waste fluid exits through proximal tubule
Azotemia (uremia) definition and symptom of:
Excessive nitrogen in blood; symptom of renal insufficiency and may occur during renal failure
Should dx for renal cysts be done with or without contrast? What should be the attenuation valur of the cyst?
Renal cyst diagnosis done w/contrast. Attenuation values of cyst should be 0
Define glioma
Group of glial tumors in brain (astocytomas, glioblasomas); glial cells are connective nerve cells
What is another name for the pituitary gland? What is it responsible for?
Hypophysis cerebri; responsible for production of hormones (somatotrophin and prolactin)
What are stereotactic unites used for?
Specifically for CT-guided biopsies; commonly for intracranial lesions
What is another name for acoustic neroma and where does it arise from?
Schwannoma; from Schwann cells in 8th cranial nerve (vestibular nerve) seen in IAC exams
What is hydrocephalus?
Abnormal accumulation of cerebrospinal fluid (CSF) in cerebral ventricular system; congenital disorder but can be caused by cranial lesions, hemorrhage, etc
How are coronal paranasal sinuses scanned?
Perpendicular to hard palate
Where is the thymus found? What happens before and after puberty?
Anterosuperior mediastinum; most visible before puberty, after puberty it becomes infiltrated with fat and difficult to image
What are the branches (from RT to LT) of the superior portion of the aortic arch?
Brachiocephalic artery, common carotid artery and the subclavian artery
What factors can be found in the periphery of an image?
Matrix size, algorithm type and section thickness
How much contrast and at what rate would opacify the mediastinum and vascular structures of the chest?
50 - 150mL @ 2.5 - 4.0mL/s
