Intro to Labs and Panels & Diagnostic imaging DSA Flashcards
What data is included in a CBC?
WBC count Hgb Hct MCH MCHC MCV RDW RBC count Platelet count (Plt)
What information is included on a CBC with differential that is not included in the regular CBC?
Percentage and absolute differential counts (PMN, lymph, baso, eos, mono, atypical mono)
What info is included in a BMP?
BUN BUN:Cr ratio Calcium CO2 Chloride Creatinine eGFR Glucose Potassium Sodium
What additional info is included on the CMP that is not included on the regular BMP?
Albumin:globulin ratio (A:G ratio) Albumin (Alb) Alkaline phosphatase (AP) Aspartate aminotransferase (AST/SGOT) Alanine aminotransferase (ALT/SGPT) Bilirubin, total Globulin, total Protein, total
Describe US imaging
Uses high-frequency sound waves to generate an image, uses US coupling gel to aid in wave transmission to transducer
Pros and cons of ultrasound
Pros: no radiation, cheaper than other modalities, non-invasive
Cons: bowel gas and lung tissue hinder US image, technician skills vary, body habitus can affect results
Indications for US imaging
Trauma RUQ pain RLQ pain Pregnancy GU complaints Acute pelvic pain Cardiac concerns Evaluate blood flow
Procedures — thoracentesis, pericardiocentesis, etc.
What is a FAST exam?
Focused Assessment with Sonography in Trauma
Rapidly assesses for free fluid in the body! — primary views are subxiphoid, RUQ, LUQ, suprpubic
Describe conventional x-ray
Patient placed between film cassette and X-ray machine
X-rays pass through body and become attenuated, having photochemical reaction with fluorescent coated film, light particles create image
Radiographic density interpretation of air, fat, soft tissue, mineral, and metal on x-ray
Air = black
Fat = dark gray
Soft tissue = light gray
Mineral = off white
Metal = bright white
Types of contrast used with x-ray
GI contrast — Barium and gastrograffin
Typically given PO or PR; radioopaque to visualize GI tract
Ideal to wait 45 min s/p ingestion for best visualization
Adverse effects are minimal — N/V/diarrhea/constipation
Pros and cons of x-ray
Pros: cheap, easily accessible, fast, excellent screening tool, widely available
Cons: 2D pic, radiation exposure, poor detail of soft tissue
Uses indicated for x-ray
Cardiovascular Pulmonary Musculoskeletal Gastrointestinal Dental Mammogram Line and tube assessment
Modality that uses continually emitted x-rays and allows for real time visualization, but images are intensified with reduced radiation exposure and attenuation is different than conventional xray
Fluoroscopy
Uses for fluoroscopy
Esophagram Upper GI study Small bowel follow-through Barium enema Cardiac Vascular
Pros and cons of CT
Pros: widely available, quick, painless, somewhat reasonable price, 3D image in cross-section
Cons: potential contrast reaction, exposure to radiation, diagnosis limitations
Type of contrast utilized in CT, and why it is used
IV iodinated contrast — given IV or intra-arterial (opacifies vessel lumen)
Used because it increases attenuation compared to the anatomical structures that surround it (enhances visibility of internal structures)
Best uses: vessels, visualize tissue changes, urinary tract, fallopian tubes, etc.; neuro — veno/angiogram, abscess, malignancy
When would you NOT use contrast with CT?
If you’re suspicious of a bleed, renal stone, retroperitoneal hematoma — contrast might block your view of the bleed/stone
CT uses in Neuro, pulm, GI systems
Neuro: HA, trauma, r/o bleeds, CVA sxs, seizure
Pulm: acute SOB, CP w/ radiation to back, assess nodules/masses
GI: explore etiology of abdominal/pelvic pain, r/o renal stone, r/o GI path
[these are not all encompassing]
MRI basics
Use of magnetic field to generate image — manipulation of polarity of H+ atoms
Tissues generate different signals based on H+ composition giving GREATER DETAIL OF SOFT TISSUES
Define T1 vs. T2 images in MRI
T1 (longitudinal relaxation time) — time it takes for excited protons to return to equilibrium; contrast used
T2 (transverse relaxation time) — determines rate at which excited protons reach equilibrium or go out of phase with each other
Preferred contrast agent in MRI
Gadolinium
Administered via IV — tremendous paramagnetic properties
Used during T1 weighted imaging to improve visability of inflammation, tumors, blood vessels, organs, blood supply, etc.
Generally well tolerated with minimal SEs; reactions uncommon
When would you use T1 vs T2 imaging for MRI?
T1 — anatomy (anatomical details, fat containing structures, subacute hemorrhages). Water and collagenous tissue (ligaments, tendons, scars) have a lower signal transduction on T1 weighted image
T2 — pathology (edema, tumor, infarction, hemorrhage). Characteristic of T2 is high signal intensity of water. Pathology is often associated with edema/fluid, thus T2 is utilized in these cases
When should you use caution when selecting MRI?
Cardiovascular devices — pacemakers, stents, mechanical valves, IVC filters, etc
Unstable patients
Claustrophobic or agitated pts
Large body habitus
