Non-Invasive Imaging of the Vulnerable Plaque and the

Vulnerable Patient

Non-invasive coronary angiography by CT and EBT

David G. King;Director, Clinical Sciences

GE Imatron

Acknowledgements:

John Rumberger:

“The tip of the iceberg” ….

20%20%

66%66%

33%33%

20%20%

Lipid RichLipid Rich

FibroticFibrotic

Fibrotic &Fibrotic &CalcifiedCalcified

The “Tip of theThe “Tip of theAtheroscleroticAtherosclerotic

IcebergIceberg””

Coronary Artery Plaque:Coronary Artery Plaque:approximate amounts of lipid rich, fibrotic and calcified plaqueapproximate amounts of lipid rich, fibrotic and calcified plaque

PlaquePlaqueDetectableDetectableby Intravascularby IntravascularUltrasound,Ultrasound,PathologyPathology

PlaquePlaqueDetectableDetectableby EBTby EBT

Acknowledgements:

John Rumberger:

“The tip of the iceberg” …..

“The Vulnerable Patient” ….. Jim Fixx,

1932-1984

Sir Winston Churchill

1874-1965

Non-calcified plaque components by EBT

Clinical significance unclear!

Points for discussion

Why non-invasive CTA?Who/what needs to be imaged?

What needs to be measured?

How can the patient outcome be changed as a result?

EBT 50 ms movie

Points for discussionCritical scanning parameters?

Scan speed

Triggering

Slice width

Image noise

Best use of dose delivered?

With or w/o contrast injection? EBT 50 ms movie

Points for discussionOptimum display of results:

Volume rendered?

Multiplanar reconstructions?

Maximum intensity projection?

Density distribution analysis?

EBT 50 ms movie

MSCT: LightSpeed – longer exposure, improved contrast resolutionSoft Plaque with Central Ulcer

Courtesy of Dr. Dowe, Atlantic Medical Imaging

Courtesy Dr. Sablayrolles Centre Cardiologique du Nord – Saint Denis

MSCT: SnapShot LightSpeed UltraStenosis in LAD 2nd Segment

Non-contrast EBT or EBA?

CAC study 50 ms EBA movie

Non-calcified ROI analysis

NormalNormal

CorAthCorAthCourtesy L.` Teichholz, MD

Density distribution in CAC studies

Density distribution• The mean voxel intensity (HU) within the ROI in

the proximal LAD is lower in patients with disease as compared to normals (p<0.005).

• The standard deviation of voxel intensities (HU) within the ROI in the proximal LAD is higher in patients with disease as compared to normals (p<0.00001).

• The percent of voxels with HU < 0 within the ROI in the proximal LAD is higher in patients with disease as compared to normals (p<0.00001).

Courtesy L. Teichholz, MD

Contrast-enhanced EBA

High speed & thin slices, yield improved spatial resolution

Venous branches, motion –diagnostic value?

The need for speed

300 msec 250 msec 200 msec 150 msec 100 msec 50 msec

Phantom “stenoses”

Requires coronary angiography?

250 msec 100 msec 50 msec

???

???

Conclusions• Benefits of high resolution

coronary vessel imaging:– Learn more about the

atherosclerotic disease process, hard & soft plaque

– Steer high risk subjects towards the appropriate intervention

– Reassure those with low probability of obstruction

– Keep the “normals” out of the cathlab