Manifestation of

coronary artery diseases

in Multi-Slice CT

Coronary angiography

Dr/AHMED ESAWY

Dr. Ahmed Esawy

MBBS M.Sc. MD

Dr/AHMED ESAWY

Manifestation of CAD

• CORONARY PLAQUE

• CORONARY ARTERY CALCIFICATION

• CORONARY ARTERY STENOSIS

• POSTOPERATIVE EVALUATION OF

CORONARY ARTERY

• ANOMALOUS CORONARY ARTERIES

• Non-atherosclerotic coronary abnormalities

1/ M. Kawasaki 2/ Myocardial bridging 3/ External compression 4/ Coronary dissection

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CORONARY

PLAQUE

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Atherosclerosis

• it was defined as slight to moderate wall change, without substantial narrowing of the vessel.

• Most acute coronary syndromes are initiated by sudden disruption of atherosclerotic plaques that are not causing significant stenosis.

• Those non stenotic plaques are associated with high lipid content.

• Calcium content, on the other hand, has been associated with plaque stability.

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Atherosclerosis

• Lipid-rich plaque in mid LAD artery at

• A) MSCT coronary angiography and

• B) Corresponding histopathologic section with a large extra cellular lipid pool

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Vulnerable Plaque

Increased risk for erosion or rupture

Associated with acute coronary ischemic events

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Calcified Plaque

CT attenuation of > 130 HU,

separated from the contrast-

enhanced lumen

> 2 independent planes

Non-Calcified Plaque

CT attenuation below contrast-

enhanced lumen but above the

surrounding tissue/epicardial fat

> 2 independent planes

Mixed Plaque

Calcified and Non-calcified Plaque

per segment

Methods - Definition of Plaque by MDCT

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Calcium Volume Score: ZERO CT angiography:

Left Main, Circumflex, and Right coronary arteries: normal LAD: eccentric, soft plaque adjacent to origin of first diagonal (60% stenosis)

Correlation recommended

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The LAD shows few small calcific and mixed plaques at its proximal one third causing no significant stenotic lesions, its middle and distal one thirds are seen patent with no lesions. It supplies early sizable single patent diagonal branch .

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41 year old asymptomatic man with normal stress thalium: Cardiac CT angiography shows ulcerated soft plaque in the proximal LAD (red boxes)

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Detection of Coronary Plaques by CTA

Sensitivity Specificity

Calcified plaque 94% 94%

Non calcified plaque 78% 87%

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Limitation of CT Plaque Imaging

Inadequate spatial resolution

Density measurement highly dependant on slice width and surrounding contrast enhancement

No activity or functional information

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Thin-slab MIP image across LAD plane shows large noncalcified plaque causing moderate (0%–30%) luminal obstruction in proximal LAD segment. Complex mixed coronary atherosclerotic plaque in middle LAD segment consists of both calcified plaque and noncalcified plaque, causing highly significant luminal narrowing. (C) 3-Dimensional volume-rendered CT image

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CORONARY ARTERY

CALCIFICATION

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Coronary artery calcification- What do we know?

Coronary artery calcification is a reliable sign of chronic atherosclerotic changes

Calcified coronary plaque = coronary atherosclerosis

Calcium is absent in normal vessel walls

Calcium seen in arterial wall from 20 years of age

Calcification increases with age and with extent of disease

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Coronary Calcification

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Coronary Calcification

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Calcium or Agatston Score

Agatston score based on the maximum CT number and the area of calcium deposit in each lesion.

The score of each single lesion on each image is the product of its area multiplied by a cofactor reflecting calcium density in each lesion.

Agatston score is not a linear measurement and is complex to calculate.

Threshold set is > 130 Hu

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Cardiac Calcium Scoring

Addition of CACS to a prediction model based on traditional risk factors significantly improved the classification of risk

Calcium Score Presence of CAD

0 No evidence of CAD

1-10 Minimal evidence of CAD

11-100 Mild evidence of CAD

101-400 Moderate evidence of CAD

Over 400 Extensive evidence of CAD

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Hn x-factor (Agatston Scoring)

130-199 1

200-299 2

300-399 3

>400 4

Area = 15 mm2 Peak CT = 450 Score = 15 x 4 = 60

Area = 8 mm2 Peak CT = 290 Score = 8 x 2 = 16

Total Score = S

Calcium Volume Scoring

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Who should be screened using CT for calcium scoring ? - Patient with risk factors for CAD (high cholesterol, DM, HTN,

Smoker, obese, FH of CAD) What are the limitations of Cardiac CT for Calcium Scoring? - weight limit, CAD can still be present without calcium even

if your calcium score is low, HR > 90, insurance coverage

- Calcium score correlates directly with risk of events and likelihood of obstructive CAD

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Predictive Value of Coronary Calcium for cardiac events

Calcium scores have predictive value for future coronary events.

Calcium score > 100 : medium risk

Calcium score > 400 : high risk

Calcium score > 1000 : very high risk (events in

the short term (1-2 years)

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Prognostic Value of Calcium Scoring

Calcium score > 100.

10 times high risk of a cardiac event than those with lower score

Cardiac events occurred earlier and more frequently in patients with scores > 1000.

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Coronary Calcium Quantification

• A 55-year-old male with calcification in LAD artery. Agatston score was 318.

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(A) Axial image obtained at level of origin of left main artery, showing extensive calcification in left anterior descending coronary artery. Aortic mechanical prosthetic valve is visualized (arrow). (B) Maximum-intensity projection image obtained from patient with ‘‘kissing’’ stents in left anterior descending coronary artery and first diagonal branch. In this case, it is difficult to evaluate lumen because of metallic artifacts. Vessels distal to stents are widely patent

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Ultra fast multislice computer tomography of coronary arteries. Calcification of coronary, score 9.8 Agatston,80 75th percentile for age and gender

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Axial image at level of left main coronary artery ostium and heavily calcified proximal and middle left anterior descending coronary artery. Cross-sectional view at level of proximal left anterior descending coronary artery. Note blooming artifact (arrowhead) caused by vessel calcification, which precludes exclusion of significant coronary artery stenosis.

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CORONARY ARTERY

STENOSIS

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Coronary Artery Stenosis

• Hemodynamically relevant stenosis was defined as substantial wall irregularity, with more than 50% vascular narrowing.

• The degree of stenosis was measured on transverse scans and MPRs by using an automated distance-measuring tool.

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Schematic illustrations of coronary artery stenosis. A–D, Illustrations show progressive narrowing of lumen (L) resulting in mild (A), moderate (B), severe (C), and complete

(D) stenosis. (Quoted from Sundaram et al., 2009).

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• Also there is growing evidence that the presence, amount, and composition of noncalcified coronary atherosclerotic plaque and the degree of coronary remodeling in proximal segments can be assessed by MDCT with a good correlation to intravascular ultrasound.

Visualization of the Coronary Artery Lumen

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Coronary Artery Stenosis

• CT coronary angiography and conventional angiography of a non calcified lesion corresponding to a significant stenosis in

the Proximal LAD artery.

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LAD stenosis

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• old male with severely stenotic mid-LAD lesion shown by 3D volume rendered CT coronary angiography and confirmed by the catheter angiogram.

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• old male with chest pain and dyspnea. The CT coronary angiography shows a proximal LAD occlusion with distal filling through collaterals.

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old male with dyspnea and abnormal triglyceride level. The CT angiography shows a soft-plaque causing non-significant stenosis of the distal Left main coronary and proximal LAD.

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Oblique coronal image obtained from patient with anginal symptoms and indeterminate stress test results, showing severe stenosis of ostium of left main coronary artery (arrow).

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invasive coronary angiography stenosis OF LAD

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CT shows long-segment irregular mild luminal narrowing(36% stenosis) with myointimal thickening in the middle RCA, whereas MR overestimates the stenosis degree in corresponding segment

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POSTOPERATIVE

EVALUATION OF

CORONARY ARTERY

BY PASS

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Postoperative evaluation of Coronary Artery

• Coronary artery bypass graft surgery Patency or occlusion of grafts can be established

by the presence or absence of contrast enhancement, respectively.

However, artifacts from metallic surgical clips may obscure the adjacent portion of a coronary graft.

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By passes

Accuracy of about 90% Excellent depiction of distal anastomoses

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Postoperative evaluation of Coronary Artery

• Coronary artery bypass graft status at MSCT coronary angiography. Axial images demonstrate occlusion of a dilated aorto coronary venous graft (large arrows) to the Lcx, while another aorto coronary venous graft (small arrows) communicating with the RCA is patent. Left IMA graft (arrowheads) to the LAD coronary artery is also patent

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Assessment of coronary artery bypass graft (CABG)

Curved axial multiplanar reformation image of the SVG shows a stent (arrowhead) and a thrombosed segment partly occluding the lumen (arrow)

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Three-dimensional volume-rendered oblique sagittal view obtained from patient with previous bypass surgery.Arrow indicates distal anastomosis of aortocoronary bypass graft to left anterior descending artery.

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3-Dimensional volumerendered image of patient showing status after left internal mammary graft to middle segment of left anterior descending coronary artery (arrowheads). Operative clips are visualized parallel to course of graft. In addition, venous coronary bypass graft can be seen between aorta and left circumflex coronary artery (arrows)

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68 year old male with atypical chest pain, submitted to revascularization surgery: bypass from left internal mamary to anterior descending artery, saphen vein to right coronary artery and saphen vein to circunflex artery. Native coronary artery assessment was impossible due to calcified plaques , possibly with multiple critical stenosis Dr/AHMED ESAWY

71 year old patient submitted to coronary artery by-pass surgery. Curved MPR may show less beam-hardening than axial section

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76 year old male patient, submitted to coronary-bypass: saphen to right coronary, saphen to 1st marginal obtuse and left internal mamary artery to descending anterior artery.

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84 year old patient with previous coronary by-pass: saphen to left marginal artery, occluded

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Looking at the MDCT:Surgery

• Overview anastomisis (start by the 3D) • Evalute grafts in axial and orhogonal MPR planes • Evaluate anastomosis and run-off • Evaluate aorta and left-ventricle size

• It is essential that the whole graft is included in the acquisition. • The most common cause of saphenous graft failure is thrombosis in

the first year and after that atherosclerotic changes ensue. • Arterial grafts usually have longer life span. • MDCT, unlike angiography, allows assessment of occluded grafts

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POSTOPERATIVE

EVALUATION OF

CORONARY ARTERY

STENT

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Postoperative evaluation of Coronary Artery

Coronary artery stent

Evaluation of stent patency is by demonstration of contrast enhancement at the leading and trailing ends of a stent.

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Evaluation of the patency of coronary vessels after intervention

MDCT is limited in its ability to visualize lumen within intracoronary stents because of metal artifacts making the detection of intrastent stenosis difficult.

The accuracy of stent evaluation may depend upon stent diameter

< 3mm inaccessible.

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Successful (LAD; 3.5 mm) Dr/AHMED ESAWY

Limited (LAD; 4.0 mm) Dr/AHMED ESAWY

Stents

Accuracy of about 70-80% Only BIG stents (≥ 3.5 mm) Only 50% of the small guy2

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Postoperative evaluation of Coronary Artery

• Coronary artery stent patency at MSCT coronary angiography. demonstrate stent (large arrows) within the middle LAD coronary artery. Stent patency is supported by adequate flow to distal segments of the artery. Arterial stenosis is noted at the leading end of a stent (small arrow).

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A patient being evaluated after intra coronary stent placement. CT coronary angiography and catheter angiogram reveal patency of the

stent.

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Imaging of coronary stents

In-stent occlusion ,two stents in the right coronary artery. CT was performed after conventional angiography failed to depict the right coronary artery. Multiplanar reformatted image shows lower attenuation inside the stent lumina than in the proximal untreated tract of the right coronary artery.

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55-year-old man with history of coronary artery stent insertion for focal severe luminal stenosis widely patent coronary stent (curved arrows) and excluded origin of marginal branch (straight arrows)

67-year-old man with history of coronary stent insertion in left anterior descending artery (LAD) LAD shows in-stent thrombosis (arrow) resulting in mild diffuse luminal disease

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LCA stent

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Curved MPR image with sharp image filter reconstruction of right coronary artery in patient with percutaneous stent placement (arrowhead). Lumen of stent (3.5-mm diameter) is patent. There is no evidence of in-stent restenosis or neointimal hyperplasia. In addition, this patient has large noncalcified plaque that protrudes into lumen of proximal right coronary artery, causing significant stenosis (arrow).

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non contrast study showing stent VRT reconstruction of the coronary tree

Contrast-enhanced showing stent Oblique MPR of the left descending artery showing a mixed softtissue and calcified plaque causing 50% stenosis

59 year old patient with stent in right coronary artery. No stenosis was found in the stent. Anterior descending coronary artery presented partially calcified plaque which caused stenosis of circa 50%.

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3D reconstruction of the coronary artery, showing stent localtion

Curved MPR of the descending coronary artery showing a plaque distal to the stent

Center: Coronal MPR showing stent permeability

5 year old female patient with percutaneous stent placement in the anterior descending artery. Perfusion cyntigraphy with 99-TCm showed apical perfusion deffect in the 17th segment (left anterior descending artery). Although the stent was apparently permeable, distal to it there is na atherosclerotic plaque which conditions a significant stenosis.

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Significant restenosis of a 3.0 mm diameter bare-metal stent in the proximal left anterior descending coronary artery (LAD) in a 63-year-old male with typical angina pectoris. Coronary CT angiography suggested occlusion of this stent (arrows Dr/AHMED ESAWY

Prestent stenosis in a 45-year-old male patient without symptoms. Curved multiplanar reformation of CT demonstrates a 30% diameter reduction in the lumen immediately proximal to the stent, resulting from a noncalcified plaque (arrow in Panel A). Significant in-stent restenosis was excluded using stent kernel curved multiplanar reformations (not shown). Conventional angiography also demonstrated the 30% prestent stenosis (arrow in Panel B). Angiographic emulation of coronary CT angiography nicely demonstrated the stenosis

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Images of three stents in venous coronary bypass grafts obtained by using 64-slice MDCT. The stent lumen appears to be clearly visualized, with no apparent restenosis.The stent diameter is 4.0–4.5 mm.A surgical metal clip causes some beam hardening artifacts, whereas the stents themselves cause few visual artifacts Dr/AHMED ESAWY

Coronary Stent Fracture

Dr/AHMED ESAWY

What to state on the examination? • Is the in-stent portion diagnostic quality? • Is there stenosis inside the stent

• Looking at the MDCT:Stents

1. Multiplanar reconstructions 2. Used curved MPR 3. If artifacts cannot be excluded then lumen is nondiagnostic.

• Presence of distal contrast does not exclude in-stent stenosis. • Major complications are stent-thrombosis and restenosis.

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Coronary Stent Fracture

Relatively High Incidence • Incidence of stent fracture : 1.7–29% • Potential Cause of in-stent restenosis (ISR) • 20% of the patients with DES ISR have stent fractures

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Longitudinal Compression

Definition • Distortion or shortening of a stent in the longitudinal axis following successful stent • New generation drug-eluting stents (DES) • Lower longitudinal strength due to thin strut

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Coronary CTA Imaging Criteria

Stent fracture - Partial or circumferential separation of the stent on visual inspection of CT image using Maximal intensity projection (MIP) or curved planar reformation technique (CPR) - Absence of a metallic strut on cross-sectional image

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Coronary CTA Imaging Criteria

Longitudinal compression - Uneven distortion or shortening of a stent in the longitudinal axis - Increased density of a strut in a shorted area

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Stent Fracture and ISR 58 yrs/M with chest pain

Stent fracture causing total occlusion

Sudden loss of stent strut Low density filling defect in stent

Total occlusion of pRCA stent was confirmed by angiography

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Longitudinal compression

Uneven distortion or shortening of stent in longitudinal axis _Increased density of strut in shorted area

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Single heart beat 320

RCA with a stent (arrowhead) in segment RCA showing a patent stent (arrowhead)

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Single heart beat 320

Curved multiplanar reconstruction using a sharp convolution kernel. In the upper right-hand corner, transverse sections of the stent and both stent edges (arrows) help confirm the absence of in-stent hyperplasia.

An invasive coronary angiogram in D confirmed the observation

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