Mod5 (diagnostic imaging) Flashcards
cardiothoracic ratio
adult heart should occupy less than or equal to 50% of thorax width; used to account for variation in body habitus
Hypertrophy
increase in bulk, results in overall muscle mass rather than chamber size; NOT detectable on x-ray
Heart Failure
blood can’t pump out sufficient enough blood to meet bodies metabolic needs
Cardiomegaly
enlargement of heart; usually above 50% cardiothoracic ratio
Pulmonary Edema
fluid in the lungs
Pleural Effusion
fluid in pleural cavity
Pulmonary Embolism
blocking of pulmonary artery; will see changes in pulmonary blood flow patterns with use of x-ray
Pulmonary Hypertension
increased resistance in artery; diagnosed by x-ray as changes in appearance of pulmonary artery
2D imaging (B-mode)
ultrasound mode; to obtain a cross-sectional (Real time) image of the heart
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
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
Doppler Shift
change in frequency of a wave for an observer moving relative to its source
Tissue Doppler Imaging
tracks movement of cardiac tissue and is of low velocity; useful method of assessing regional differences in cardiac wall function
3D imaging
ultrasound mode; obtains 3D volumes of systolic and diastole to determine QUANTITATIVE EJECTION FRACTION; especially ***useful for diagnosing myocardial ischemia
frontal view of heart (x-ray)
gives assessment of overall size; produces posterior-anterior view
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
