Intro to cross sectional, Ultrasound, Nuc Med

ultrasound

Uses high-frequency (3-20 mHz; megahertz) sound waves with a transducer generated at 20,000 vibrations per second (hertz/second)

Reflected soundwaves echoes are recorded and shown as an image in real time

Transducer transmits inaudible soundwaves into the body, as it echoes from the body’s fluid and tissues, transducer records the strength and character of the waves, then displayed

3-20mHz

ultrasound frequency

20,000

transducer vibrations

attenuation coefficient

• How much of the sound wave will get absorbed

• How much passes through

• How much bounces back

piezoelectric crystal

Converts the electricity into sound waves- and then echoes into electricity

functions of the transducer

generates sound waves

detects reflected sound waves

types of transducers

curvilinear

linear

endocavity, transvaginal, transrectal

intraoperative probe

curvilinear

Low frequency 5mHz

Abdominal, obstetrics, pelvis

linear

High frequency 15mHz

Great detail

Superficial structures

Thyroid, scrotal, musculoskeletal, soft tissue masses

curvilinear

transducer type?

linear

transducer type?

endocavity

transvaginal

transrectal

8mHz

intraoperative probe

Very high frequency

Directly on organ or vessel

Liver transplants, vascular

endocavity, transvaginal, transrectal

transducer type?

intraoperative probe

transducer type?

sagittal (long)

transverse

imaging planes

echogenicity

describes the tissue in relation to another tissue, or as compared to its normal state

benefits of ultrasound

No radiation, or harmful effects to patient

Low cost

Live imaging

Virtually no pain to patient

Quick results

Quick test time

No (measurable) weight limit

Portable

doppler ultrasound

Evaluates blood flow of major arteries and veins in the extremities - arms/legs

hyperechoic

white on image hy

hypoechoic

dark on image

anechoic

no color on image

indications of doppler ultrasounds

Arteriosclerosis of the arms or legs

Blood clot (deep vein thrombosis)

Venous insufficiency

Evaluate injury to the arteries

Monitor of arterial reconstruction and bypass grafts

carotid ultrasound

Evaluates how well blood is flowing through the carotid arteries

indications of carotid ultrasound

Blood clotting (thrombosis)

Narrowing in the arteries (stenosis)

Blood flow; other causes of blockage in the carotid arteries (surgery related complications)

baby hip ultrasounds

Evaluation for Developmental Dysplasia of the Hip (DDH)

why babies get hip ultrasounds

Typically performed if baby is breech or Hx of DDH in family

cranial ultrasound (neonatal)

hydrocephalus (enlargement of the ventricles)

detect bleeding within the brain tissue or the ventricles

assess for damage to the white matter brain tissue surrounding the edges of the ventricles during difficult birthing process

evaluate for congenital abnormalities

locate the site of an infection or tumor.

physical relationship among structures

3-d concept

evaluation = soft tissue structures

what does cross sectional anatomy show

advantages of cross sectional anatomy

eliminates overlapping structures

helps to differentiate between adjacent structures

offers view of anatomy in a variety of planes

sagittal

1

coronal

2

axial

3

mm to cm

slice thickness can vary from?

AP

how are images oriented?

CT

Generates a three-dimensional image of the body from a large series of two-dimensional X-ray images taken around a single axis of rotation

AP and lateral

what scout images are taken to designate where the slices will be?

iodine based and barium sulfate

what contrast is used in CT?

advantages of CT

Visualization of anatomy without superimposition of structures

• Axial imaging

• Computerized mathematical reconstruction of digital numbers

Ability to differentiate small differences in density of anatomic structures and abnormalities

• 2 tissues with similar densities distinguished

CT indications

Diagnose muscle and bone disorders

Detect internal injuries and internal bleeding

Pinpoint the location of a tumor, infection or blood clot

Guide procedures such as surgery, biopsy and radiation therapy

Detect and monitor diseases and conditions

MRI

Utilizes a powerful magnetic field to align the magnetization of some atoms in the body

• Magnetic properties of hydrogen atoms

  • Human body = 80% hydrogen

1973

when was MRI discovered?

coil

what is placed around the area of interest in MRI to obtain the info of that specific area of anatomy

• the magnet aligns the single protons in the hydrogen nuclei within the field

T1 weighted MRI images

Fat appears bright

Water appears dark

Best for anatomy

T2 weighted MRI images

Water appears bright (white)

Fat appears dark

Best for pathology

gadolinium

what contrast is used in MRI?

Less adverse reactions and eliminated through kidneys easier

why is gadolinium used in MRI?

advantages of MRI

No exposure to ionizing radiation

Superior contrast resolution

Superior tissue characterization

Multi-planar capabilities

Possibly safer intravenous contrast agents

Visualization of angiography without using contrast

MRI indications

A noninvasive way to examine organs, tissues and the skeletal system by producing high-resolution images that help diagnose a variety of problems

contraindication of CT

high dose

extraversion of veins

allergic reaction

claustrophobia

how MRI works

axial

what plane?

coronal

what plane?

sagittal

what plane?

contraindications of MRI

take longer

claustrophobia

contrast involved

magnet → can affect pacemakers/ defibrillators, metal pieces in body

narrow bore → larger patients may not fit