Post on 15-Jan-2016
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CARDIOVASCULAR IMAGING WITH COMPUTED TOMOGRAPHY(CT)
Hakan SOLMAZ, Institude of Biomedical Engineering, Boğaziçi University
Computed Tomography of the Heart
Key Points
greater spatial and temporal resolution detailed anatomic information image reconstruction in 3-D estimation of calcified and noncalcified
plaque in coronary arteries
Computed Tomography of the Heart
A Brief History of CT
Comes from the Greek word "tomos" meaning "slice" or "section" and graphia meaning "describing".
The first clinical CT scanners were installed between 1974 and 1976, were dedicated to only head imaging.
The first CT scanner developed by Hounsfield.
Computed Tomography of the Heart
How Does CT Work?
combines the use of a digital computer together with a rotating x-ray device
cross sectional images or "slices" lungs, liver, kidneys, pancreas, pelvis,
extremities, brain, spine, and blood vessels .
Computed Tomography of the Heart
How Does CT Work?
Computed Tomography of the Heart
How Does a CT Look Like
Outside view of a CT system Inside view of a CT systemshowing the patient table showing the X-ray tube and detector
Computed Tomography of the Heart
Why is CT Performed?
CT has the unique ability to image a combination of soft tissue, bone, and blood vessels
Conventional X-Ray imaging shows the dense bone structures,
X-ray angiography depicts the blood vessels, MR imaging is excellent in showing soft tissue
and blood vessels
Computed Tomography of the Heart
Why is CT Performed?
CT can provide detailed cross sectional images and diagnostic information for nearly every part of the body;
the brain, vessels of the brain, eyes, inner ear, sinuses the neck, shoulders, cervical spine and blood vessels of the neck the chest, heart, aorta, lungs, mediastinum the thoracic and lumbar spine the upper abdomen, liver, kidney, spleen, pancreas and other
abdominal vessels
Computed Tomography of the Heart
CT of the Heart
Planar Imaging vs CT Imaging Planar image processors can not show
smaller structures They create images of the silhouette of the
contrastfilled vessels 3-D CT image can reveal complex anatomy
and spatial relationships
Computed Tomography of the Heart
CT of the Heart
Planar Imaging vs CT Imaging CT imaging is slower than planar imaging• planar radiograph ~ 4 to 10 ms exposure
time• tomographic image slice ~ 50 to 250 ms each image slice must be acquired during the
late diastole
Computed Tomography of the Heart
CT of the Heart
standard chest radiographwhich is a planar projection
three-dimensional computed tomographic image
Computed Tomography of the Heart
Two Types of CT Scanners
Electron-beam CT developed for cardiac imaging; 50-100 ms
per image slice reflecting electron beam onto a stationary
tungsten target Multidetector CT developed for body imaging mechanically rotating an x-ray tube
Computed Tomography of the Heart
Two Types of CT Scanners
new multidetector CT scanners; high spatial and temporal resolution
Computed Tomography of the Heart
Principles of Cardiovascular CT Examination
the image data are acquired during one breath-hold within a chosen scan protocol
most protocols require iodinated contrast agents to enhance cardiovascular structures
two Acquisition modes; The sequential 2-D mode The spiral 3-D mode
Computed Tomography of the Heart
Principles of Cardiovascular CT Examination
A smaller slice thickness allows better resolution radiation exposure and scan time increase volume covered is reduced A slower heart rate allows better CT image quality betablockers are desirable to slow the heart rate
Computed Tomography of the Heart
Clinical Cardiovascular Indications
CT can be used for a number of cardiovascular indications, but sometimes with another imaging test;
Hypertension; CT + MRI acute midsternal chest; CT + angiography
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Cardiac CT is especially useful in evaluating the
myocardium, coronary arteries, pulmonary veins, thoracic aorta, pericardium
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Cardiomyopathy with contrast enhanced CT ischemic cardiomyopathy, CT typically shows;• Focal ventricular wall thinning• Fibrous or calcified replacement of myocardium• Aneurysm formation
Computed Tomography of the Heart
Clinical Cardiovascular Indications
non-ischemic cardiomyopathy, CT typically shows;
• global dilatation and myocardial thinning,• focal myocardial hypertrophy
Computed Tomography of the Heart
Clinical Cardiovascular Indications
two chamber view three chamber view
Computed Tomography of the Heart
Clinical Cardiovascular Indications
four chamber view short-axis view
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Coronary artery stenosis with contrast enhanced CT scan allow one to assess stenosis Coronary CT angiography is challenging the blood vessels are small, tortuous, and in rapid motion during the
cardiac cycle CT doesn’t have enough spatial and temporal resolution to show all the
coronary segments There may be plaque calcification
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Uses of CT angiography; To rule out severe proximal stenosis To assess anomalous coronary arteries and to determine their
origins and their relationship evaluate the severity of stenosis in venous aortocoronary grafts
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Coronary CT can exclude significant obstructive disease and assess atherosclerotic plaque
Computed Tomography of the Heart
Clinical Cardiovascular Indications
The smaller images are the views at the level of aortic valve
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Pericardial diseases; Detailed anatomic information about the pericardium Inflammation of the pericardium can be detected with
contrast-enhanced CT
Computed Tomography of the Heart
Clinical Cardiovascular Indications
Cardiac masses can be described on CT according to their, size, density, and spatial relationship to adjacent structures Although CT can also detect tumors, it is limited
Computed Tomography of the Heart
Clinical Cardiovascular Indications
additionaly; valve stenosis and regurgitation, aortic disease, pulmonary embolism, pulmonary veins imaging
Computed Tomography of the Heart
Frequently Asked Questions
Does the CT examination hurt? No, it does not, except the case of iodine contrast injection, which is
discomfortable during the needle is placed Is CT Imaging Safe? the diagnostic benefit of a CT scan usually outweighs the risk of x-ray
radiation exposure or injections of imaging contrast
Computed Tomography of the Heart
Frequently Asked Questions
How long will the CT examination take? the actual procedure will typically be between 10 minutes and 45
minutes Can I Move While I am in the CT Scanner? You should not move when you are on the CT table and the images are
being acquired. CT exams of the chest and abdomen require the patient to hold their breath for a short period of time, for example, 10 to 25 seconds
Computed Tomography of the Heart
References
http://imaginis.com Physical Principles of Medical Imaging; Perry Sprawls, Proff. Of Radiology,
Emory University School of Medicine http://www.radiologyinfo.org http://www.clevelandclinic.org/heartcenter http://www.ctisus.org