What Is CT Coronary Angiography? How Is CT Coronary Angiography Performed?

Virtual angiography (coronary CT angiography) is an advanced technological diagnostic test that visualizes blockages and narrowings in the vessels supplying the heart in three dimensions using a computed tomography device, without making any surgical incision. This procedure is performed painlessly by administering iodinated medical dye (contrast agent) through a superficial vein in your arm and having you hold your breath for a few seconds while the device rapidly rotates around you. Unlike conventional angiography, there is no need to enter the body with a catheter through the groin or wrist. This innovative imaging technique, which scans intravascular structures directly within seconds, is one of the most comfortable methods for detecting the risk of a heart attack at an early stage before any physiological symptoms appear.

What Is Virtual Angiography and How Does It Visualize the Heart Vessels?

Virtual angiography is an application that is quite different from conventional imaging methods in the medical world, is entirely technology-focused, and keeps patient comfort at the highest level. While in conventional methods thin, long tubes called catheters are inserted through arteries in areas such as the groin, wrist, or arm, no surgical instrument is introduced into the body in this modern technique. The entire process is based on the principle of high-resolution scanning applied externally.

The basis of the procedure is the contrast agent administered into the body through an ordinary and superficial vein in the patient’s arm. This special medical dye containing iodine reaches the heart and the coronary vessels surrounding the heart like a network within seconds after entering the bloodstream. At this exact moment, the computed tomography device comes into operation. The ultra-sensitive detectors inside the device, called photon counters, rotate around the heart in a tiny fraction of a second and capture thousands of cross-sectional images.

These images transfer the movement of blood through the vessels, the thickness of the vessel walls, and possible blockages to the computer screen with remarkable clarity. The software of the device combines these two-dimensional sections to create a three-dimensional model of the heart and vessels that corresponds precisely to reality. This makes it possible to conduct a detailed examination as though the heart had been entered and the vessels were being examined under a microscope.

Which People with Which Complaints Should Undergo Virtual Angiography?

The most important reason why this imaging technology is so valuable in medical practice is that its exclusion power is nearly flawless. If the heart vessels appear clear as a result of the scan, the possibility that the person has a life-threatening, severe obstructive coronary artery disease is considered to have been almost completely eliminated. This prevents exposure to unnecessarily difficult and invasive procedures.

This method is an excellent decision-making tool, especially for patients in whom no definitive conclusion can be reached or suspicious findings are detected in preliminary examinations such as an exercise test or cardiac ultrasound. Congenital vascular anomalies or situations requiring risk assessment before pregnancy also fall within the scope of this application.

It is quite common for people who experience certain physical symptoms in daily life to be referred for this examination. The main complaints that should be evaluated are as follows:

• Chest pain
• A feeling of tightness in the chest
• Palpitations
• Unexplained shortness of breath
• Rapid fatigue during exertion
• Pain radiating to the back
• Numbness spreading to the left arm

Which Values Does Virtual Angiography Examine in Predicting a Heart Attack in Advance?

Thanks to today’s advancing medical technology, imaging procedures are no longer limited to showing only the amount of blood passing through a vessel or how narrow the vessel has become. At the same time, they analyze the tissues surrounding the heart and vessels at the cellular level and provide unique biological markers that can signal heart attacks that may occur in the future well in advance.

Another vital measurement is the thickness of the pericoronary adipose tissue. This special fatty tissue, which surrounds the main vessels supplying the heart in a millimetric layer, acts like a mirror of vascular health. Even if no narrowing or blockage has yet formed inside the vessel, structural changes in this fat layer surrounding the vessel provide an early warning that a dangerous plaque may develop in that vessel in the near future. Thanks to these biomarkers, preventive medicine becomes much more powerful.

What Should Patients Do During the Preparation Process Before Virtual Angiography?

Obtaining the most efficient, clearest, and most accurate result from this advanced imaging technique depends on a meticulous preparation process carried out by the patient before the day of the scan. The heart is a dynamic organ that continuously beats and moves. Since it is physically difficult to take a clear photograph of a moving object, the body must be brought to a certain level of calmness.

The first rule of the preparation process is fasting. Solid food and fluid intake should be completely stopped during the four- to six-hour period before the scan. The iodinated medical dye that will be administered through the arm during the procedure may cause unwanted reflexes such as nausea or vomiting; when the stomach is empty, this risk is completely eliminated. People with diabetes who use regular medication may need to temporarily stop their medication under physician supervision so that these drugs do not interact with the contrast agent in the body.

One of the most important rules is to avoid substances that affect heart rate. Foods with a stimulating effect increase the pulse, causing the heart to beat too quickly and the images to appear blurred. Likewise, substances that cause constriction in the vessels may make the vessels appear narrower than they actually are and lead to an incorrect diagnosis. The substances that must be completely stopped twenty-four hours before the scan are as follows:

• Coffee
• Tea
• Chocolate
• Energy drinks
• Carbonated and acidic beverages
• Cigarettes
• Tobacco products

How Does the Virtual Angiography Procedure Progress Minute by Minute in the Imaging Room?

The patient who has successfully completed the preparation stages is taken into the specially designed imaging room and positioned on their back on the comfortable movable table of the tomography device. The first step of the process is to place small adhesive electrodes on the patient’s chest area in order to monitor the electrical activity and rhythm of the heart instantaneously.

The essential rule for obtaining high-quality images free from motion distortion is for the pulse to remain below sixty-five beats per minute in a calm and regular rhythm. If the patient’s pulse is high due to anxiety or physiological reasons, rhythm-regulating medications are administered intravenously immediately before the scan or during the procedure in order to slow the heart rate. Once the pulse reaches the desired ideal calmness, a vasodilator spray is applied under the patient’s tongue so that the coronary vessels can be examined in their widest state.

When the procedure begins, the automatic pump delivers the iodinated medical dye into the body through the intravenous line in the arm. The sudden sensation of warmth spreading through the body and the unusual metallic taste in the mouth during this injection are completely expected and normal. When the contrast agent reaches the heart, the device begins the actual scan, and at this moment the patient is asked to take a deep breath and hold it so that the rib cage does not move. The scan ends after this breath-holding period, which lasts an average of ten seconds.

What Are the Technological Differences Between Virtual Angiography Devices in Hospitals?

Tomography technology has advanced at a breathtaking pace in recent years. For this reason, the quality of the procedure is directly related to the strength of the equipment available in the hospital. The capacity of devices is generally expressed by the term “slice,” which indicates how wide an area the device can photograph in one complete rotation. Due to its complex structure, the heart requires the most advanced technologies.

Sixty-four-slice devices, which are accepted as standard, offer sufficient minimum quality for patients with a regular heart rhythm who can comfortably hold their breath. However, when the pulse increases, deterioration in image quality may occur with these devices. Advanced systems with wider detector areas, such as two-hundred-fifty-six- or three-hundred-twenty-slice systems, have the ability to scan the entire heart simultaneously within a single heartbeat. This capability reduces image errors caused by heart movement to almost zero.

Dual-source systems, which represent the highest level of technology, contain two separate X-ray sources and two separate detectors. These devices are so fast that they can obtain perfectly clear images even in patients with extremely irregular heart rhythms or in patients with palpitations whose pulse cannot be reduced. Commonly used device configurations are as follows:

• Sixty-four-slice devices
• One-hundred-twenty-eight-slice devices
• Two-hundred-fifty-six-slice systems
• Three-hundred-twenty-slice systems
• Dual-source systems

What Should Be Considered During the Day After the Virtual Angiography Procedure?

The hospital process is considered complete for the patient the moment they get up from the table after the examination is finished. Since no surgical intervention has been performed and there is no wound or incision on the body, the patient does not need bed rest, hospital observation, or restriction of daily life. The patient may immediately return to work, personal responsibilities, or social life. However, at this point, there is an extremely important and vital physiological task that must be fulfilled.

The iodinated contrast agent administered into the circulatory system during the procedure to make the vessels visible must be safely eliminated from the body. The kidneys, which are the body’s main filtration facility, filter this substance and remove it from the body through urine. Large amounts of water should be consumed to prevent the kidneys from becoming excessively strained during this filtration process and to preserve kidney function.

Drinking plenty of water in addition to normal fluid intake throughout the day on which the procedure is performed helps the medical dye to be cleared rapidly from the body. On the other hand, if the person undergoing the procedure is a breastfeeding mother, there is a possibility that a very small amount of the contrast agent circulating in the blood may pass into breast milk. For this reason, as a precaution, it may be recommended that breast milk be expressed and discarded for a certain period and not given to the baby.

How Does Virtual Angiography Measure Arterial Stiffness and Calcification?

Arterial stiffness and blockages are not diseases that appear suddenly; they are the result of a slow, silent accumulation that continues for years. Over time, structures called plaques form as cholesterol, calcium, and various cells accumulate within the vessel walls. While conventional imaging methods examine only the space inside the vessel, this advanced computerized scan virtually enters the vessel wall and analyzes the structure, hardness, and characteristics of these plaques.

Plaques inside the vessel are divided into two groups. Some are completely calcified, hardened like stone, and stable structures. Others contain cholesterol, are inflamed, and have a soft structure. These soft plaques are clinically very dangerous because they carry a risk of suddenly cracking and rupturing, similar to a pimple. A ruptured plaque causes a blood clot to form in that area within seconds and may result in the vessel suddenly becoming blocked, leading to a heart attack. Early detection of these hidden soft plaques saves lives.

In addition, with a method called calcium scoring, the calcium burden in the vessels is measured as a numerical value. Thanks to artificial intelligence-supported algorithms, the patient’s risk of having a heart attack within the next ten years is calculated mathematically from the obtained images. A score of zero indicates that the risk is extremely low, while high scores indicate that urgent precautions should be taken. The calculated calcium risk score groups are as follows:

• Zero-score group
• Group below one hundred points
• Group between one hundred and four hundred points
• Group above four hundred points
• Group above one thousand points

In Which Special Situations May Virtual Angiography Be Insufficient?

Like every innovative technology in medicine, this imaging method also has physical and technical limitations and certain special situations in which it may be insufficient. No matter how advanced the devices are, the images obtained in some patient profiles may not provide the clarity required to make a definitive diagnosis.

One of the main limitations is the glare problem known in medical terminology as the “blooming artifact.” If the patient has a very widespread, very thick, and extremely dense layer of calcium in the vessels, enormous glare appears in the image when the X-rays strike these calcium blocks. This brightness causes the actual vessel lumen beneath the calcium to remain obscured and not be seen clearly. Even if the vessel is actually wide, this glare may create a misleading appearance as though it were blocked.

Likewise, in patients with very thin and small-diameter stents in the heart, the metallic mesh structure inside the stent may distort the images and make it impossible to evaluate the inside of the stent. This procedure cannot be performed in people with a severe allergy to iodinated substances or in those with severely impaired kidney function. The main patient profiles in whom image quality is reduced and the procedure cannot be applied are as follows:

• Those with advanced vascular calcification
• Those carrying very thin cardiac stents
• Those with severe kidney failure
• Those with an allergy to iodinated medication
• Patients with rhythm disorders whose pulse cannot be controlled

What Does the CAD-RADS Report Given After Virtual Angiography Mean?

After the images are examined and evaluated digitally, a special reporting system is used to establish a global medical standard and place the patient’s treatment plan on a clear roadmap. This international system is called CAD-RADS. It categorizes complex medical data and serves as a clear guide showing which physician the patient should consult at each stage.

Category zero proves that the vessels are completely clear and that there is not even the slightest plaque formation. Categories one and two show that mild thickening has begun in the vessel walls, but that this condition does not disrupt blood flow; patients in this group are kept under control through lifestyle changes, healthy nutrition, and cholesterol medications. Category three indicates borderline narrowing and requires additional examinations such as an exercise test to determine whether the heart is receiving adequate blood supply.

Categories four and five are the stages at which alarm bells begin to ring. These levels mean that severe narrowings or complete blockages that significantly obstruct blood flow in the vessels have been detected. Patients classified at category four or five should proceed to the treatment planning stage without delay. These international standard reporting levels are as follows:

• Category zero
• Category one
• Category two
• Category three
• Category four
• Category five

If the Virtual Angiography Result Is Critical, Which Treatments Does Interventional Cardiology Apply?

This is precisely where the most definite limitation of this advanced tomography technology begins. No matter how clear or flawless the images it obtains are, this method is only a highly advanced camera that documents the current condition. It has absolutely no ability to open a blocked vessel, eliminate plaque, or intervene in and treat the problem at that moment. When a serious narrowing is detected in the vessels as a result of imaging, the entire process is transferred to Interventional Cardiology specialists for the definitive and permanent treatment of the patient.

Interventional cardiology is the branch of medicine that eliminates these detected mechanical problems simultaneously. Specialist physicians treat the patient in specially sterile catheter laboratories that meet operating-room standards. Using only local anesthesia, the vascular system is entered, most commonly through the artery in the wrist, with very thin, flexible, and long tubes. These thin tubes are advanced millimeter by millimeter until they reach the opening of the blocked vessels supplying the heart directly.

From this point onward, diagnosis instantly turns into treatment. Extremely thin guidewires are sent into the narrowed and blocked area. Special deflated balloons are placed over these wires in the narrowed section and inflated under very high pressure, compressing the calcium and cholesterol plaque blocking the vessel against the vessel walls. Immediately afterward, drug-eluting stents are permanently implanted inside the vessel to prevent it from closing again and to support its structure. The blocked pathway is completely reopened to circulation within minutes, and the heart muscle receives oxygen again.

Especially during an active heart attack, when even seconds are of vital importance, losing time with tomography devices may lead to fatal consequences. In such crisis situations, these direct vessel-opening procedures performed by interventional cardiology specialists are among the greatest life-saving achievements offered by medicine. The main life-saving procedures performed by interventional cardiology are as follows:

• Conventional invasive angiography
• Balloon angioplasty procedure
• Drug-eluting stent placement
• Intravascular clot removal
• Opening chronic total occlusions

What Are the Main Differences Between Gold-Standard Conventional Angiography and Virtual Angiography?

Although both methods focus on examining heart health, their functions, application methods, and problem-solving capacities in the medical world are entirely different from one another. One is a flawless observer, while the other is a definitive operator that eliminates the problem at its source. The aim is not for these two methods to replace one another, but for them to complement each other through a flawless strategy.

The first method is a three-dimensional imaging procedure performed by administering medication through a superficial vein without any physical intervention in the body. It is a unique safety filter for determining whether a disease is present, screening low-risk patients, and preventing unnecessary hospital admissions. However, if there is extensive calcification inside the vessel or a narrow stent that was previously placed, the lens of this imaging device may not provide a clear picture because of glare.

In contrast, the gold-standard conventional method performed by interventional specialists is an invasive and physical process that extends directly into the heart. Calcification or metallic reflections never affect the clarity of this method; the blood passing through the vessel is observed with millimetric precision. Its greatest and most unique difference is its treatment capability. The moment the diagnosis is made, the narrowing can be opened with a balloon and stent before the patient leaves the table, completing the treatment.

Frequently Asked Questions

Prof. Dr. Kadriye Kılıçkesmez

Prof. Dr. Kadriye Orta Kılıçkesmez is one of the leading figures in the field of Turkish cardiology. She was born on January 24, 1974, in Tekirdağ. After completing her undergraduate education at Istanbul University Cerrahpaşa Faculty of Medicine, she chose cardiology as her specialty and received her specialist training at the Cardiology Institute of the same university. In 2015, she was appointed by the university to establish the Şişli Etfal cardiology clinic and Angio laboratory. Becoming a professor in 2017, Kadriye Kılıçkesmez established the cardiology clinic and Angio laboratory of Prof. Dr. Cemil Taşçı Hospital in 2020 and ensured that the clinic became a training clinic.