Scoring coronary artery calcium (CAC) with cardiac CT

Coronary CT is the only imaging method that can detect subclinical plaque and early vessel calcification before blood flow reduction occurs. In this video taken from our Cardiac CT Essentials course, you will learn how to measure coronary artery calcium so that you can catch cases of patients with calcified plaque (and thus at high risk of future cardiac events) and intervene before they even show any symptoms.

This slide shows the classical progression of atherosclerosis the vessel lumen starts off by being normal this is then followed by fatty streaks accumulating with the internal wall and thereafter by white blood cells and red blood cells later on foci of calcification accumulate as calcified plaque at this stage there is no significant reduction in the luminal

Caliber and blood flow to the heart muscle is preserved stress testing with echocardiography myocardial perfusion scintigraphy and treadmill testing only have the ability to detect coronary disease that causes a significant reduction in blood flow conny ct on the other hand is the only imaging modality that has the ability to detect subclinical clark an early

Vessel calcification in the wall of a vessel before a reduction in blood flow occurs this differs from invasive angiography which looks at a reduction in luminal caliber but cannot detect the pathological processes occurring within the vessel wall as per corny ct and calcium scoring can so what is corny artery calcium scoring if we consider a normal kearny artery

The blood flow is preserved to the heart muscle when one develops significant plaque the blood flow to the muscle is compromised and this can become manifest with symptoms of angina connie autry calcium scoring is a technique that detects and measures the amount of calcium within the coronary arteries by doing this clinicians are able to identify patients who may

Have calcified plaque but who have no symptoms the benefit of this is that patients are at a high risk of future cardiac events can receive thereafter early risk factor modification such as a commencement of aspirin statins and receive appropriate lifestyle changes so how is connie artery calcium performed a corney artery calcium scan is the low radiation dose

Non-contrast prospective ecg gated scan the scan is usually acquired from the level of the bifurcation of the main pulmonary artery as a starting point so this point is almost invariably above the origins and proximal segments of the carney arteries images are then acquired every three millimeters to the bottom of the heart this slide shows an example of a page

With no corny artery calcium when calcium is present it appears similar to that scene of the spine and the sternum and is depicted by a white color this is an example of a patient who has calcification present in all three of their coronary arteries there is calcification present in the left mainstem proximal middle ad segments the first diagonal branch the left

Circumflex and the mid right corney artery you can also see calcification in the aortic valve and the descending aorta here we can see the calcification in the left mainstem and also the proximal el-ad segment as we scroll down through the imaging set we can see further corney artery calcium in the proximal to mid led segment and also within the left circumflex

Artery if we scroll down further we can see calcification in the first diagonal branch and also within the mid segment of the right coronary artery ultra colony calcium scan is acquired this then requires quantification using a system that was developed by arthur agate-stone this takes the mean hounsfield unit of the calcified part being evaluated and depending

Upon the value attributes this a multiplication factor for example if a calcified plaque had a hounsfield unit of 320 the multiplication factor would be three is 600 the multiplication factor would be four and so forth here we can see how this multiplication factor comes into play if we take a vessel that has two sequential calcified plaques the first has a hound

Fill unit score of 250 so the multiplication factor will be two this is then multiplied by the area of the plaque giving a total value of ten agate-stone units for the second plaque the mean hounds filled number is 450 so the multiplication factor in this case is four this is multiplied by the area which is ten to give 40 agates turn units the total cornea artery

Calcium score is thereafter the sum of the agaton score for every calcified plaque within the cornea arteries and in this case the agaton score would be 50 agate certain units now fortunately every ct workstation has software that is able to calculate the coronary calcium score using this technique automatically all is required from the operator is to mark the

Calcified plaque within the carney arteries in this example the software color codes anything with a hounds full unit score above 130 which represents calcium into yellow there is only a tiny amount of calcium in the proximal led segments and the total coronary calcium score was 0.8 agate-stone units let us work through a case together using the same principle this

Is an example with more extensive corney artery calcification the total coronary artery calcium in this case was 1061 angerstein units what does the corney artery calcium score actually mean cornie artery calcification only occurs in the presence of atherosclerosis it therefore shows the effect of all of an individual’s can’t even risk factors on their core knee

Arteries at a single point in time it is influenced by smoking diabetes mellitus hypertension hypercholesterolemia inactivity genetic factors and also elevated body mass index numerous studies have shown that corny artery calcification is an exceptionally powerful prognostic marker for future cardiac events it represents the most powerful cardiovascular risk marker

That cardiologists have and currently it outperforms all other risk scoring methods the greater the degree of coronary artery calcification the greater the risk for future cardiovascular events indeed it can be seen as be taking a snapshot of an individual’s coronary arteries at a single point in time and seeing what effect the sum of all of their cardiovascular

Risk factors in their lifetime have heard on their carney arteries i would now like you to comment on the corney artery calcification seen on the current scan let us look through this case together were you able to see the calcification at the left mainstem the proximal led segment and the middle ad segment and also coronary calcification in the left circumflex

Artery the proximal right coronary artery and also the mid right corney artery segment let us do one together on the left-hand side you can see the coronary calcium scan and on the right hand side you can see how coronary artery calcium scoring is performed in real-time in a patient with significant calcification you can play note that this particular software color

Codes the calcium one selected into a different color for each vessel note how the distal led is being marked with an orange color for each calcified plaque and now as we move to the right colley artery the right cornea artery calcified plaque is being color coded as green as we move down the right cornea artery each calcified plaque is selected and color coded

In the same color schematic we are now approaching the inferior part of the heart and looking at the distal calcified plaque within the right coronary artery once all of the coronary calcium has been marked and color coded appropriately we are able to receive an output of the total coronary artery calcium in this particular case we can see that the total cornea

Artery calcium score for all of the coronary arteries was 1061 agate-stone units as well as being an exceptionally useful technique for evaluating cardiac risk colly artery calcium scoring is often routinely performed just prior to a coronary ct angiogram this has a number of benefits that include better planning of the scan range for the corney ct angiogram and

Also giving a clinician an idea as to what the burden of disease is likely to be before the angiogram component of the scan has been performed

Transcribed from video
Scoring coronary artery calcium (CAC) with cardiac CT By Medmastery