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 system showing 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 radiograph which 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

two Acquisition modes; The sequential 2-D mode The spiral 3-D mode 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

A smaller slice thickness allows better resolution 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