Mod5 (diagnostic imaging) Flashcards by Amanda Haluk

cardiothoracic ratio

adult heart should occupy less than or equal to 50% of thorax width; used to account for variation in body habitus

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Hypertrophy

increase in bulk, results in overall muscle mass rather than chamber size; NOT detectable on x-ray

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Heart Failure

blood can’t pump out sufficient enough blood to meet bodies metabolic needs

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Cardiomegaly

enlargement of heart; usually above 50% cardiothoracic ratio

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Pulmonary Edema

fluid in the lungs

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Pleural Effusion

fluid in pleural cavity

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Pulmonary Embolism

blocking of pulmonary artery; will see changes in pulmonary blood flow patterns with use of x-ray

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Pulmonary Hypertension

increased resistance in artery; diagnosed by x-ray as changes in appearance of pulmonary artery

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2D imaging (B-mode)

ultrasound mode; to obtain a cross-sectional (Real time) image of the heart

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M-mode

ultrasound mode; 2D imaging used to find placement of M-mode; amplitude of signal is recorded along length of single beam; great at evaluating opening and closing of valves

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Doppler Technique

ultrasound mode; detects direction and average speed of blood flow (velocity); based on diffs btw freq of transducers and blood cell freq signal

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Doppler Shift

change in frequency of a wave for an observer moving relative to its source

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Tissue Doppler Imaging

tracks movement of cardiac tissue and is of low velocity; useful method of assessing regional differences in cardiac wall function

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3D imaging

ultrasound mode; obtains 3D volumes of systolic and diastole to determine QUANTITATIVE EJECTION FRACTION; especially ***useful for diagnosing myocardial ischemia

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frontal view of heart (x-ray)

gives assessment of overall size; produces posterior-anterior view

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Lateral view of heart (x-ray)

to view patients left side; x-ray passes from R-L

Echocardiography

use of ultrasound waves to visualize structure and function of heart; relies on difference of tissue density to produce image constructed from reflected waves (TTE, contrast, stress, transesophageal)

pulsed wave (pw) doppler

analyzes blood flow at specific sample points; only at low velocities; determines exact location of left ventricular outflow obstruction

continuous wave (cw) doppler

records along entire length of cursor; records higher velocities; determines peak gradient across stenotic valve

colour flow mapping doppler

same principle as pw doppler (sample at specific pt, low velocities); colour used to rep average velocity of blood flow; to observe regurgitation/shunts

Transthoracic echo (TTE)

patient lies on side; Uses five windows to obtain views of the heart; views allow observation of heart w/o obstruction from ribs/lungs

Contrast echo

enhance endocardial border definition; uses contrast agent to assess ejection fraction and visualize thrombus. used when TTE is not adequate

stress echo

determines wall motion abnormalities from exercise/drug-induced stress; useful at diagnosing myocardial ischemia/CAD

Transesophageal echo (TEE)

provides clearer image of TTE without interference from lungs/bones; assess endocarditis, preoperative assessment, exclusion of embolism and septal defects

Clinical App of Echo

ventricular assessment and ejection fraction calculation, view valvular lesion, assess wall motion abnorm, diagnose cardiomyopathy/pericardial disease

Myocardial perfusion imaging

type of nuclear cardiology; determines ischemia/infarction from CAD; acquire image using SPECT; areas of infarct show lack of thallium accumulation (COLD SPOTS)

Hibernating Myocardium

when both sets of images (before/after exercise) show persistent cold spots in absence of scarring

MIBI (99 Sestamibi)

nuclear cardiology; demo relationship btw amount absorbed by myocardium in relation to blood flow; distribution reflects delivery of blood (perfusion)

MUGA (multi-gated acquisition nuclear scan/ radionuclide ventriculography)

evaluates ventricular systolic function; technetium 99m injected and binds to RBCs; determines ejection fraction

First pass MUGA

obtains rapid sequential cardiac images during INITIAL passage of tracer through heart/vessels; assess extent of L-R cardiac shunts

Gated Equlibrium MUGA

continous imaging of heart chambers at PREDETERMINED TIME(gate) after QRS

Positron Emssion Tomography (PET)

positron emitting isotope (rubidium 82) attaches to metabolic tracer (FDG); areas of decrease blood flow show increased FDG uptake; to assess myocardial metabolism and perfusion

CT (Computed tomography)

detailed anatomic cross-sections of thorax; to visualize size, shape, and wall thickness of chambers and great vessels

Magnetic Resonance Imaging (MRI)

powerful magnetic fields and non ionized radio frequency radiation applied to body; image created when radio-freq is suddenly discontinued; differentiate small contrasts in tissue

Coronary Magnetic Resonance Angiography

differentiates laminar blood flow from turbulent blood flow (turbulent from obstruction/narrowing from stenosis)

contrast enhanced MRI

differentiate btw impaired but viable tissue from scarred unviable tissue