Imaging of Cardiac Pathology

Question 1

what are the types of imaging available?

Answer 1

•echo •nuclear •CT scans

Question 2

most common use of testing

Answer 2

•determination of function/valve anatomy •diagnosis of myocardial ischemia •determine the severity of CAD •non-invasive hemodynamics •prognosis

Question 3

critical features of imaging

Answer 3

•risk/benefit ratio •comprehensive capabilities -muscle, flow and/or artery •accuracy •reproducibility •overall cost to society (misdiagnosis) •length of examination and interpretation •accessibility •portability

Question 4

muscle

Answer 4

•echocardiography •cardiac MRI

Question 5

flow

Answer 5

•nuclear SPECT •cardiac MRI

Question 6

artery

Answer 6

•computed tomography •cardiac MRI •angiography

Question 7

transthoracic echo

Answer 7

Inexpensive (relatively)

No risks / discomfort

Non-radiating

Non-nephrotoxic contrast agents

Comprehensive morphology / physiology

Ideal for serial exams

Sound above human hearing (20,000Hz) Piezo-electric crystals are struck by alternating electric currents and create these high frequency vibrations Transducers send and receive signals Pulsed-reflected US through the heart provides the position and motion of cardiac structures

can convert velocity to pressure using Bernoulli Equation

pressure = 4 * Vsquared

•tricuspid regurgitation to dteremine peak pulmonic arterial pressure

-pulmonary hypertension

•velocity across aortic valve to measure peak aortic pressure

-aortic stenosis

Question 8

nuclear SPECT

Answer 8

Single

Photon

Emission

Computed

Tomography

Dominant non-invasive diagnostic test

 6 million / yr in US.

 Sensitivity 80-90%; specificity, 75-85%

Drawbacks

 Attenuation of signal = false positives

 Increased signal (hepatobiliary uptake)

 Ionizing-radiation exposure

 Long duration of test

Question 9

CT angiography

Answer 9

• excellent method of assessing patients
• vein grafts

*arterial grafts

Question 10

cardiac MR

Answer 10

Magnetic resonance occurs only in atomic nuclei with unpaired spin

MR does not interfere w/ electrons in the outer shell

 Fundamentally safe

 Unlike ionizing radiation (x-rays) which bind to electrons and potentially alter DNA

Advantages:

Function (+ stress)

Perfusion

Delayed enhancement VIABILITY

Coronary wall

No radiation

No renal toxicity

Disadvantages

Availability

Off-line interpretation

Gating / motion artifact

Pacemakers / ICD

High tech / MD skills

Distorted ECG