Coronary CT

CORONARY CT

Dr. Suhas Basavaiah

Resident (MD Radio-diagnosis)

Coronary Anatomy The coronary arteries are the blood vessels that supply

blood to the heart muscle itself.

There are numerous collaterals but they are not always sufficient to maintain adequate myocardial blood supply in case of occlusion of a coronary artery.

The right heart has a more favorable ratio of muscle fibers to capillaries, which is why it is more susceptible to toxic damage, while the left heart is more likely to suffer ischemic damage.

The two coronary arteries arising from the right and left aortic sinus are the first branches of the ascending aorta.

Coronary artery

Coronary artery is a vasa vasorum that supplies the heart.

Coronary comes from the latin ”Coronarius” meaning “Crown”.

Coronary artery The coronary artery arises just

superior to the aortic valve and supply the heart

The aortic valve has three cusps –

left coronary (LC), right coronary (RC) posterior non-coronary (NC)

cusps.

Right coronary artery

Originates from right coronary sinus of Valsalva

Courses through the right AV groove between the right atrium and right ventricle to the inferior part of the septum

The right coronary artery. Course of the right coronary artery (RCA) on a series of axial images acquired from top to bottom (A-F). (A-C) The aorta gives rise to the proximal segment (1), which courses in an anterolateral direction. (D) The middle segment of the RCA takes a nearly vertical downward course (2). (E) The RCA then turns to the left and continues to the posterior aspect of the heart (segment 3) along a nearly horizontal course on the diaphragmatic surface of the heart. (F) At the crux of the heart—the junction of the septa and walls of the four heart chambers—the RCA branches into the posterior descending artery and right posterolateral branch (4). Ao, aorta; RV, right ventricle; LV, left ventricle; LA, left atrium.

Branches of RCA

Right coronary artery

Conus artery

Sinu nodal artery

Marginal artery

Post. Descending IV artery

AV nodal artery-

Conus branch

SINU NODAL BRANCH

AV Nodal Branch

Conus branch – 1st branch supplies the RVOT Sinus node artery – 2nd branch - SA node.(in

40% they originate from LCA) Acute marginal arteries-Arise at acute angle

and runs along the margin of the right ventricle above the diaphragm.

Branch to AV node Posterior descending artery : Supply lower

part of the ventricular septum & adjacent ventricular walls.

Arises from RCA in 85% of case.

Right coronary anatomy

AO

LA

RCA

CONUS BR

RCA

SAN

1 2

3 4

RCA

AM

RCA

AMAM

Area of distribution

RT CORONARY ARTERY----

1)Right atrium

2)Ventricles

i) greater part of rt. Ventricle except the area adjoining the anterior IV groove.

ii) a small part of the lt ventricle adjoining posterior IV groove.

3)Posterior part of the IV septum

4)Whole of the conducting system of the heart, except part of the left br of AV bundle

Left coronary artery

Arises from left coronary cusps

Travels between RVOT anteriorly and left atrium posteriorly.

Almost immediately bifurcate into left anterior descending and left circumflex artery.

Length – 10-15mm

The left anterior descending coronary artery. Course of the left anterior descending coronary artery (LAD) on a series of axial images acquired from top to bottom (A-H). (A) The aorta gives rise to the left main coronary artery (5), which gives off the proximal segment (6) of the LAD anteriorly. (B-C) Along its further course, the artery divides into the middle LAD segment (7) and a diagonal branch (9). (D) In most individuals, there is a second branching of the LAD. A second diagonal branch (10) arises from the distal segment (8). (E-H) The distal parts of the LAD can be followed as they course in the interventricular groove toward the apex. Note that the diagonal branches may occasionally be larger than the main LAD. Ao, aorta; RV, right ventricle; LV, left ventricle; LA, left atrium.

The left circumflex coronary artery. Course of the left circumflex coronary artery (LCX) on a series of axial images acquired from top to bottom (A-H). (A) The aorta gives rise to the left main coronary artery (5), which gives of the proximal segment (11) of the LCX posteriorly. (B-D) Along its further course, the artery divides into the middle segment of the LCX (13) and a marginal branch (12). (E-H) The middle segment (13) then gives off a second marginal branch (14). The circumflex branch turns around the left border and continues on the diaphragmatic surface (distal segment, 15). Ao, aorta; LA, left atrium; arrow, segment 12

Left coronary artery

LAD

Diagonal artery

Lt Conus artery

Anterior Septal br

Circumflex artery

Obtuse marginal branches

Ventricular branches

Atrial rami

LEFT CORONARY ARTERY

Ramus Intermedius

Area of Distribution

1) Left atrium.

2) Ventricles

i) Greater part of the left ventricle, except the area adjoining the posterior IV groove.

ii) A small part of the right ventricle adjoining the anterior IV groove.

3) Anterior part of the IV septum.

4) A part of the left br. Of the AV bundle.

DOMINANCE

Determined by the arrangement that which artery reaches the crux & supply posterior descending artery

The right coronary artery is dominant in 85% cases.

8% cases - - circumflex br of the left coronary artery

7% both rt & lt coronary artery supply posterior IVseptum & inferior surface of the left ventricle-here it is balanced dominance.

Coronary artery dominence

CORONARY ARTERY ANOMALIES

The diagnosis of coronary artery anomalies has previously required invasive coronary angiography; however, in up to 50% of patients, the coronary artery anomalies may be incorrectly classified during invasive angiography.

This misclassification may result from the difficulty in delineating the precise vessel path within a complex 3D geometry using a relatively restricted two-dimensional view.

Coronary CTA has been shown to accurately depict the anomalous vessel origin, its subsequent course, and the relationship to the great vessels.

Two studies comparing CCTA and invasive coronary angiography found that invasive angiography was able to detect 80% of the anomalous origins but only 53% of the anomalous coronary courses and resulted in a precise anatomic diagnosis in only 55% of patients.

In a multicenter coronary artery CT registry, CCTA was able to unequivocally demonstrate the origin and the course of the anomalous artery in all patients with equivocal findings on invasive coronary angiography.

Shi H, Aschoff AJ, Brambs HJ, et al. Multislice CT imaging of anomalous coronary arteries. Eur Radiol. 2004;14(12):2172-2181.

Schmitt R, Froehner S, Brunn J, et al. Congenital anomalies of the coronary arteries: imaging with contrast-enhanced, multidetector computed tomography. Eur Radiol. 2005;15(6):1110-1121

Datta J, White CS, Gilkeson RC, et al. Anomalous coronary arteries in adults: depiction at multi-detector row CT angiography. Radiology. 2005;235(3):812-818.

Evaluation of coronary anomaly. A. Three-dimensional (3D) rendering image showing an anomalous left circumflex arising from the right coronary sinus and coursing between the aorta and the left atrium. B. 3D rendering image showing a coronary aneurysm involving the LM, the proximal LAD, and a diagonal branch. LAD, left anterior descending (coronary artery); LM, left main.

ATHEROSCLEROSIS

Fatty streaks composed of lipid-laden macrophages (foam cells))

Plaque :- Soft necrotic core of lipid with surrounding chronic inflammatory cells covered by fibrous cap.

Fatty streaky progress to plaque

Progressively enlarge causing critical

stenosis

Ulcerates or ruptures leading to thrombosis and critical ischemia

Pressure atrophy of the media causing

aneurysmal dilatation

Coronary pathology in acute coronary syndrome. The evolution of coronary lesions follows a progression from (1) initial plaque formation, (2) plaque growth, (3) plaque vulnerability and rupture, and (4) thrombosis.

CORONARY CT ANGIOGRAPHY

AVAILABLE TECHNOLOGY Currently, two competing CT technologies are used-

1. Electron-beam CT and

2. Mechanical multi–detector row CT

Electron beam CT : Used specifically for cardiac imaging d/t high temporal

resolution Uses a rapidly rotating electron beam, which is reflected

onto a stationary tungsten target Imaging done in sequential mode, where single

transverse sections are sequentially acquired. However, due to higher cost and limited availability,

MDCT is most commonly used.

CT CORONARY ANGIOGRAPHY Coronary computed tomography angiography

(CCTA) is an effective noninvasive method to image the coronary arteries

MDCT has multiple detector rows are placed opposite the x-ray tube which shortens the examination time and improves the temporal resolution

The new generation 64 detector MDCT system has allowed higher isotropic resolution, with visual clarity of up to fifth- order coronary arterial branches.

Which ? MDCT is optimum

4/8-slice –For detection CAD sensitivity: 86% and ruled out in 64 of 80 patients (specificity: 81%).

16 slice MDCT -sensitivity: 96% ,specificity: 83

64 slice CT -sensitivity: 97% ,specificity: 92%

High-quality source images are the most important prerequisite for the diagnostic assessment of coronary CTA.

Image quality depends on: 1. Heart rate – Image quality improves with

heart rate less than 65. 2. Proper coronary CTA scan and post

processing protocol. 3. The synchronization of raw image data with

electrocardiography (ECG) information 4. Breath Holding : 45 sec (4 detector) to 9

sec (64 detector)

INDICATION

Screening high risk patients

Evaluation of chest pain

Post procedural study

Post CABG

Post stent

Dilated Cardiomyopathy

Non-cardiac surgery evaluation

CONTRAINDICATIONS Absolute contraindication :

1. Hypersensitivity to iodinated contrast agent

2. Pregnancy Relative contraindication

Irregular rhythm Renal insufficiency (sr. creatinine > 1.5 mg/ml) Hyperthyroidism Inability to hold breath for 10 sec History of allergy to other medication Metallic interference (e,g: pacemaker, defibrillator

wires)

PATIENT PREPARATION

Avoid caffeine and smoking 12 hours prior to the procedure to avoid cardiac stimulation.

B- blocker : Oral or I.V B-blocker is used in patient with heart rate greater than 60 bpm

oral 50- 100 mg metaprolol administered 45 min to 1 hr before procedure.

or I.V Metaprolol 5 to 20 mg at the time of procedure

Sublingual Nitrates or Nitroglycerine: given immediately before the procedure to dilated the coronary arteries.

Patient Positioning and Preparation for Scanning

Patients are positioned on the CT examination table in the supine position

ECG leads are attached to obtain an adequate ECG tracing.

Intravenous access via a large intravenous line (18 gauge cannula) is necessary to ensure easy injection of the viscous contrast agent at a flow rate of 5 mL/s

Training of patients with repeated breath holds

ECG gating protocols For ECG synchronized scanning of the cardiac

region, two different approaches are taken 1. Prospective ECG gating

2. Retrospective ECG gating

PROSPECTIVE ECG GATING

Scan acquisition is triggered by the ECG signal at the prospected mid-diastolic phase of the cardiac cycle.

Between 40% and 80% of the R-R interval

Benefits: Smaller patient radiation dose

Limitation: Reconstruction of image in different cardiac phase for functional analysis of ventricle is not feasible

A diagram showing the division of the cardiac cycle into 10% intervals. The two ovals cover the two regions of the cardiac cycle where the motions are the most still. The light blue oval covers the mid- to end-systolic phase, and the red oval covers the mid- to end-diastolic phase.

Hurst’s The Heart

RETROSPECTIVE ECG GATED SCANNING

Heart region is scanned continuously Contiguous data of cardiac region are

acquired Patient’s ECG is recorded at the same time Scan data with least cardiac motions , usually

the diastolic phase , are selected later for image reconstructionAdvantage:•Entire volume is acquired continuously and gapless•Image may be reconstructed with overlap

Disadvantage:• Higher patient radiation exposure

Diagram showing effect of ECG dose modulation. In Fig 1- continuous scanning throughout the cardiac cycle with full tube current , resulting in high radiation dose. In Fig 2- ECG dose modulation is turned on and full tube current is applied only during 40-80% of cardiac cycle, where cardiac motion is least. In Fig 3- To further decrease radiation, a single phase of cardiac cycle is selected for scanning during which full tube current is applied.

ECG controlled dose modulation

Image acquisition and reconstruction

The acquisition of the dataset for coronary CTA consists of 3 steps :

1. Topogram 2. Contrast medium protocol : to ensure

homogeneous contrast enhancement of the entire coronary artery tree

3. Coronary CTA scan

TOPOGRAM• Native coronary

arteries # Begin above carina # Tortuous aorta or

prominent upper left heart border – begin scan 1-2cm higher

• Bypass Grafts Veins: top of arch LIMA: above clavicles

SCAN START POSITION

SCAN ENDING POSITION

Image acquisition end 2 cm below the diaphragm

Contrast Medium Protocol

Optimal coronary artery opacification depends on :

1. The iodine medium concentration – (300-400 mg iodine/ ml is used)

2. The volume and rate of contrast administration

3. Timing of the contrast medium delivery.

Volume and rate of contrast administration

Using 64 detector MDCT technology:

80ml of contrast agent is injected at 6 ml/sec f/b 40ml saline solution at 4ml/sec

Using 16 detector MDCT technology: 100- 120 ml of contrast agent @ 4 to 5 ml

per sec.

Delivery of contrast medium s/b timed to ensure that the scan of cardiac region will occur at the peak of opacification of the coronary tree.

It can be assessed by two techniques-

1. Automated contrast bolus tracker technique- the ROI is placed on ascending aorta. When ct value of ROI is greater than predetermined threshold of 100- 150 HU, the scan begins.

2. Test bolus scan – here a small bolus of contrast is injected to determine contrast transit time. The time from the start of the injection to the peak contrast enhancement in the ascending aorta determines the scan delay after the initiation of contrast material administration.

After contrast administration, CT is obtained in single breath-hold

Scan volume covers the entire heart from the proximal ascending aorta (approximately 1–2 cm below the carina) to the diaphragmatic surface of the heart

Scanning protocol

Post processing protocol

The axial source images obtained are utilized for multiplanar reconstructions in at least 2 planes

Commonly used techniques are : Maximum intensity projection (MIP), Volume rendering (VR), Multiplanar reconstruction (MPR) or Curved planar reconstruction (CPR)

3D Reconstructions The CT angiography dataset can be used to

generate a 3D display of the entire heart, which can be rotated to view the heart from different perspectives.

Such 3D reconstructions primarily serve to provide an overview of the anatomic situation or to present the findings to patients or clinicians and should not be used for primary interpretation of the CT data.

TREE VR

3D/ VR

Maximum Intensity Projection

Maximum intensity projection is a visualization method for three-dimensional data that extracts voxels of the highest intensity for two-dimensional display in a defined plane.

This technique is well suited to generate angiography-like images of vessels in any plane.

Curved multiplanar reconstruction (MPR) image

"Ribbon" multiplanar reconstruction (MPR)

Maximum intensity projection (MIP)3D Volume-rendering

Multiplaner reconstructions

CORONARY CT ANGIOGRAPHY OF NON-CALCIFIED PLAQUE

CORONARY CT ANGIOGRAPHY OF CALCIFIED PLAQUES

A significant stenosis ofLAD is confirmed on coronary angiography

Extensive calcified plaques arenoticed in the proximal and middle segments of left anterior descending (LAD) on curved multiplanar reformatted

Extensive calcified plaques are noticed in volume rendering images

CORONARY CT ANGIOGRAPHY OF MIXED PLAQUES

Coronary CT angiography of mixed plaques. Mixed plaques are observed in the proximal segment of the left anterior descending (LAD) artery with > 50% stenosis (a, arrow). Coronary angiography confirms the significant stenosis of the LAD (b, arrow).

RADIATION DOSE

Ranges between 12-16 mSv depending on CT scanner and type of ECG gating used.

ECG-controlled dose modulation systems allows reduction of radiation exposure by upto 50%

Lower the KVP to 100 causes significant dose reduction.

A prospective gate window of 20% over diastole in patients with HR of 60, can reduce total dose by 80%.

Coronary artery assessment

The best evaluated coronary artery is the LAD as it runs along the axis of the scan and is not significantly affected by cardiac movements

The LAD is well visualized in 76-96% of cases The left CX artery may be affected by cardiac

motion artifacts and can be assessed in 52-95% of cases

RCA is most affected by cardiac movement Proximal coronary segments are better

visualized than distal ones.

GRADING

0 Normal: Absence of plaque and no luminal stenosis

1 Minimal: Plaque with <25% stenosis

2 Mild: 23%-49% stenosis

3 Moderate: 50%-69% stenosis

4 Severe: 70%-99% stenosis

5 Occluded

Raff GL, Abidov A, Achenbach S, et al: SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography. J Cardiovasc Comput Tomogr 3:122, 2009.

CCTA, adequate interpretation & reporting Society of Cardiovascular Computed Tomography (SCCT)Underlying principles of interpreting

Raff GL, et al SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography. J Cardiovasc Comput Tomogr. 2009 Mar-Apr;3(2):122-36. Epub 2009 Jan 29.

CCTA, adequate interpretation & reporting Society of Cardiovascular Computed Tomography

(SCCT)Stenosis Grading


CCTA, adequate interpretation & reporting Society of Cardiovascular Computed Tomography

(SCCT)Structured reporting


BYPASS GRAFT IMAGING

1. Graft location : MDCT can accurately characterize the origin, course, and touchdown of prior bypass grafts

2. Graft patency : Patency of both arterial and venous bypass grafts can be assessed.

Recent studies have suggested that the sensitivities and specificities of MDCT for detecting stenosis or occlusion of bypass grafts, when compared with invasive angiography, approaching 100%.

Before reoperative CABG, cardiac CT is considered an appropriate indication, defining the relationship of sternal wires to cardiac and graft structures for the purpose of planning surgical reentry techniques.

High-risk findings on cardiac CT include cardiac structures adjacent to or adherent to the sternum and coronary bypass grafts that extend into the midline.

CT images also guide the surgical team on optimal locations for aortic crossclamping, to avoid regions with extensive CAC or atheroma .

Occasionally, artifacts related to metallic clips can interfere with assessment of the distal anastomosis of an arterial graft (internal mammary or radial artery graft).

Maluenda G, et al: Perioperative outcomes in reoperative cardiac surgery guided by cardiac multidetector computed tomographic angiography. Am

Heart J 159:301, 2010.

Cardiac CT provides high accuracy for evaluation of coronary bypass grafts owing to their large size, often limited extent of calcified atherosclerosis, and limited mobility, as shown in the oblique multiplanar reformat (A) and three-dimensional volume-rendered reformat (B).

High-risk substernal reoperative anatomy in a patient with previous coronary bypass surgery including a coronary bypass graft (arrow)

immediately beneath the sternum, shown in axial (A) and sagittal (B) views. The right ventricle is immediately adjacent and adherent to the

sternal wire (C, arrow).

Three-dimensional rendering image shows the adhesion of the mid-portion of the left internal mammary artery graft to the sternum. Fuster V, Walsh RA Hurst’s The Heart

Noncontrast CT showing extensive aortic calcification (“porcelain aorta”). A, In the coronal plane, calcification extends from the aortic sinotubular junction to the aortic arch. B, C, Cross-sectional images (at levels indicated by arrows extending from A) from the upper (B) and lower (C) ascending aorta show the circumferential nature of the calcification

STENT PATENCY

Image artifact from metallic stents limits the application in patients with prior coronary stent procedures.

Small stents are difficult to evaluate .

However, 90% accuracy can be obtained in stents 3 mm or greater in diameter with the use of sharp kernel and wide display window.

Quantitative assessment of within-stent contrast density may assist in the diagnosis.

A contrast density ratio of 0.81 between the stent (proximal, mid-, and distal portions) and the aorta showed a sensitivity of 90.9% and a specificity of 95.2% in-stent stenosis for stents down to 2.5 mm in size.

Abdelkarim MJ, Ahmadi N, Gopal A, et al: J Cardiovasc Comput Tomogr 4:29, 2010

CORONARY CT ANGIOGRAPHY OF A PATENT STENT

A patent coronary stent is noticed in the proximal left anterior descending (LAD) artery on a curved multiplana reformatted (MPR) image with clear demonstration of the intrastent lumen without in-stent restenosis.

Stent imaging with cardiac CT. A, A large stent with uniform contrast attenuation in the lumen, indicating patency. B, A small stent in the left anterior descending artery with another stent in the proximal diagonal branch. Three reconstruction/display settings are shown: a medium-soft kernel, a sharp kernel, and sharp kernel reconstruction displayed with a wide window width. Visualization of in-stent restenosis in the diagonal branch is optimized with the third approach (i.e., sharp kernel, wide window display width).

CORONARY CT ANGIOGRAPHY OF IN-STENT RESTENOSIS

An in-stent restenosis is present at the distal part of the right coronary artery (RCA) stent which is demonstrated as the low-attenuating area on longitudinally straightened (a), curved multiplana reformatted (b) and cross-sectional images (c).

ADVANTAGES OF MDCT Non invasive procedure without any hospital

stay. MDCT CA can precisely identify total

occlusion, indicate cause and extent. Morphology of the occluded segment and the

time the artery was occluded In acute obstruction, low density intraluminal

defect caused by thrombosis with an increase in luminal area and diameter are seen.

In chronic cases , the obstruction shows calcified or mixed plaques with the artery lumen with normal or slightly narrowed lumen

Predictors of failure to open an occluded artery include

1.occlusion length greater than 15mm 2.Presence of severe calcification in the

compromised segment.

Vessel distal to the completely obstructed segment is visualized , not possible with catheter angio.

Limitations of CT coronary angio Rapid (>80 bpm) and irregular heart rate.

High calcium scores (>800-1000)

Presence of stents

Contrast requirements

small vessels (<1.5 mm) and collaterals

Obese and uncooperative patients

Radiation exposure

TRIPLE RULE OUT(TRO) CTA Triple rule-out (TRO) CTA can evaluate the coronary

arteries, pulmonary arteries, aorta, and intrathoracic structures in selected patients presenting with acute chest pain of unclear etiology.

The new 64-slice MDCT scanners can provide high-quality TRO CTA studies by tailoring the injection of iodinated contrast to provide simultaneous high levels of arterial enhancement in the coronary arteries and aorta (>300 HU) and in the pulmonary arteries (>200 HU).

Halpern EJ. Triple-rule-out CT angiography for evaluation of acute chest pain and possible acute coronary syndrome. Radiology. 2009;252(2):332-345

Radiation exposure is minimized by limiting the imaging window to include from the aortic arch down through the heart, rather than encompassing the entire chest.

In addition, the same imaging parameters, such as prospective gating and current modulation, used in CCTA are incorporated into the TRO CTA to limit ionizing radiation doses to between 5 and 9 mSv.

When used in the emergency department on appropriately selected patients, TRO CTA can eliminate the need for further diagnostic testing in >75% of patients.

Calcium scoring

Coronary calcium screening is intended to detect calcified atherosclerotic plaque burden as a surrogate marker for coronary atherosclerosis.

Based on the principle that– Obstructive atherosclerotic plaques are

calcified – so called “Hard Plaque” Calcium is not present within the wall of a

normal coronary artery

INDICATION Women over the age of 55 and men over

the age of 45 should consider the coronary calcium scan, if they have coronary artery disease risk factors:

---- Family history of heart disease ---- High cholesterol level

(hypercholesteremia) ---- High blood pressure ---- Smoking, Obesity ---- Diabetes ---- High-stress lifestyle

Minimum requirement for calcium scoring

HOW THE PROCEDURE IS DONE

Preparation:

# No special preparation is necessary

# Avoid caffeine and smoking four hours before the exam.

# Heart rate ＞ 90/min → β- blocker

Protocol :

# No contrast used

# 2.5 mm to 3 mm slice thickness

# Prospective ECG –gated acquisition for calcium scoring.

The threshold for calcification is set at an attenuation value of ≥ 130 HU, for an area of > 1mm2 along the course of the coronary arteries.

For MDCT the threshold value for calcification is 90 HU ( because of high signal to noise ratio )

Automated measurement of the lesion area in mm2 and maximum CT No. (HU) of each lesions are recorded.

Density score of the lesions are determined as

The total as well as individual coronary artery calcium score is calculated using special software at the workstation

Methods Quantitative calcium scores are calculated

according to the method described by Agatston et al .

Calcium score= density score x volume

CAC scores are typically reported for each major coronary artery (left main, left anterior descending, circumflex, right coronary artery) separately

The total score is achieved by adding up each of the scores for all the slices

WHAT DOES THE CALCIUM SCORE REPRESENT

Detection of any degree of coronary calcium on CT indicates that CAD is present

It provides a quantitative estimation of plaque burden. Higher the score the larger the plaque burden & higher the subsequent cardiac events.

Score of zero indicates unlikely chance of CAD, does not eliminate the possibility.

CALCIUM SCORING GUIDELINESCALCIUM SCORES

IMPLICATION RISK OF CORONARY ARTERY DISEASE

0 No identifiable plaque Very low, less than 5%

1 – 10 Minimal identifiable plaque

Very unlikely, less than 10%

11 – 100 Definite, at least mild atherosclerotic plaque

Mild or minimal coronary narrowing likely

101 - 400 Definite, at least moderate plaque

Mild coronary artery disease highly likely, significant narrowing possible

401 or higher

Extensive atherosclerotic plaque

High likelihood of at least one significant coronary narrowing

The CAC score can be classified into five groups:

1) zero, no coronary calcification;

2) 100, mild coronary calcification;

3) > 100 to 399, moderate calcification;

4) >400 to 999, severe calcification;

5) > 1000, extensive calcification.

CORONARY CALCIUM SCORING

Advantages of Coronary calcium scoring

Gives an idea of whether CAD is present, despite a lack of symptoms or is likely to develop in next few years develop in next few years.

Non invasive and less time consuming. No contrast required needed. The examination can suggests the

presence of CAD even when the coronary arteries are <50% narrowed.

LIMITATIONS Not all calcium deposits mean there is a

blockade and not all blocked arteries contain calcium.

The earliest form of CAD soft plaque, cannot be detected by cardiac CT.

A high heart rate interferes with the test.

Men <35 yrs and women <40 yrs are not likely to benefit from cardiac CT for calcium scoring unless there is risk factors such as diabetes or a strong family history of heart disease.

SUMMARY AND CONCLUSION Coronary CT angiography represents the most

rapidly developed imaging modality in cardiac imaging.

Demonstrates high diagnostic accuracy.

Utilization of coronary CT angiography must be defined in terms of whether it leads to the greatest benefit and whether the radiation risk may be greater than the benefit expected from the CT examinations.

Thank You

Coronary CT

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