1. Imaging techniques in cardiology 1 : echocardiography, CT, MRI, SPECT

Define Transthoracic Echocardiography

ultrasound beams are directed across the chest wall to obtain images of the heart

What are the indications of TTE

• LVEF, MI & complication, wall motion abnormalities

• Chamber size, wall thickness, Valve morphology, proximal great vessel morphology, pericardial effusion

• congenital HD, syncope, murmurs, unexplained hypotension,

Defien Transesophageal echo (TEE)

Invasive procedure used to complement TTE where an Ultrasound probe inserted into the esophagus to allow for better resolution of the heart and structures eg left atrium, mitral and aortic valves, inter-atrial septum

What are the indications of TEE

• the initial test in certain lifethreatening

  situations, (e.g. Aortic dissection)

• when other tests contraindicated (e.g. Ct angiography in patient with renal

  failure)

• Intracardiac thrombi, tumours, valvular vegetations, aortic atheromas, prosthetic

  valve function, shunt,

• When TTE not enough

• Evaluation for left atrial/left atrial appendage thrombus in a patient with atrial fibrillation/atrial flutter to decide on whether to do electrical cardioversion or ablation

risks of TEE

• Esophageal perforation

• Gastrointestinal bleeding

• pharyngeal hematoma

Why is cardiac MRI used?

it offers high spatial resolution, eliminates the need for iodinated contrast, and does not involve exposure to ionizing radiation

Indications of cardiac MRI

• assessment of congenital cardiac anomalies

• abnormalities of the aorta

• assessment of viable myocardium

• assessment of cardiomyopathies

What are the contraindications of cardiac MRI

metallic foreign bodies/implants

Define Contrast Enhanced CT coronary angiography

fast ECG-synchronized multi-slice CT image acquisition in the heart to enable noninvasive imaging of the coronary arterial tree

Indications of contrast enhanced CT angiography

• assess previous stenosis or graft not seen in CT angiography

• assess coronary artery

ContraI of contrast enhanced CT angiography

• renal dysfxn

• allergy to contrast dye

Risks of contrast enhanced CT angiography

radiation exposure

what happens in nuclear cardiology/spect

myocardial perfusion imaging (MPI) with ECG-gated single photon emission computed tomography (SPECT), using radiolabelled tracer

Which tracers can be used

• Thallium-201 (201 Tl, a K + analogue)

• Technetium-99 (99 Tc)-labeled tracer

What are the uses of Spect

• evaluates myocardial viability

• detects ischemia

• assesses perfusion

• assesses LV fxn

• predicts likelihood of future cardiac events

When are images taken

images of the heart obtained during stress and at rest 3-4 h later

What types of stress can be induced?

treadmill or IV vasodilator stress (dipyridamole, adenosine,

regadenoson)

What are the indications of SPECT

• ECG can’t be interpreted appropriately

• dx ischemia

• pt’s symptoms have changed since the last imaging

• to dx CAD in an ACS pt with normal ECG & serum biomarkers.

Contraindications especially of vasodilators

• reactive airways

• sick sinus syndrome

• high deg AV block

• hypotension

  not of vasodilators

• pregnancy

what arre the risks of SPECT

• radiation exposure