Noninvasive MDCT- based Imaging of the Coronary

Arteries

Udo Hoffmann, MDDirector of Cardiac CT Research

Assistant Professor of Radiology, Harvard Medical School

Massachusetts General Hospital Boston, MA

Challenge of Coronary Artery Imaging

Small Vessels with Complex Anatomyin Rapid Motion

Cornerstone Invasive Selective Coronary Angiography

Prerequisites for Prerequisites for Successful Cardiac CT ISuccessful Cardiac CT I

• Temporal Resolution• Spatial Resolution• Volume Coverage

• 330- 400 ms gantry rotation (165- 200 ms) temporal resolution (half scan reconstruction)• 0.4 x 0.4 x 0.6 - 0.75 resolution• single breath hold 8 - 14 sec• 40 - 80 ml of contrast agent (4-5 ml/s)• 500 - 950 mAs tube current (modulation)• 7 – 24 mSv

64 Slice MDCT64 Slice MDCT Protocol Protocol for Coronary for Coronary AngiographyAngiography

Prerequisites for Prerequisites for Successful Cardiac CT IISuccessful Cardiac CT II• Appropriate Breath Hold

exact instructions (mid inspiration)exercise and observe heart rate

• Low heart rate, NSR (<65 bpm)

Beta Blocker PO/IV

Retrospective ECG gating

Axial Source Images

Thin MIP 3D VRT Curved MPR

Post Processing

P A C S

Comprehensive Cardiac CT Examination

betablocker i.v., sublingual Nitroglycerine betablocker i.v., sublingual Nitroglycerine

O F F L I N E

Detection of significant coronary artery stenosis

Systematic Review on Diagnostic Accuracy of CT-

based Detection of significant Detection of significant CADCAD

• 30 studies • 1849 patients• 12913 coronary segments

•13 EBCT - 847 patients•10 - 4/8 MDCT - 588 patients•7 - 16 MDCT - 414 patients

Hoffmann et al, JAMA 2005 submitted

Diagnostic Accuracy of EBCT, 4 - and 16 - slice MDCT

Assessable

SegmentsPooled

Sensitivity 

97.5% CI 

 Pooled Specific

ity97.5% CI

All CT 83% 80.6%-85.3% 94% 93.2%-94.6%

EBCT 83% 79.5%-87.0% 90% 89.0%-91.8%

MSCT 83% 79.8%-85.7% 96% 95.1%-96.5%

4- and 8-slice 82% 78.3%-85.2% 96% 95.0%-

96.6%

16-slice 86% 80.3%-91.4% 96% 94.4%-97.1%

All Segments

    

All CT 72% 69.5%-74.3% 84%83.3%-84.9%

EBCT 71% 67.0%-75.2% 77%75.0%-78.2%

MSCT 72% 71.4%-73.2% 88%87.9%-88.7%

4- and 8-slice 62% 60.9%-63.6% 84%

83.3%-84.6%

16-slice 84% 83.1%-85.1% 94%93.6%-94.9%

RCA StenosisRCA Stenosis

n Sens. Spec. n.e.

Ropers ACC 2005 84 91% 93% 7%Leschka Eur Heart J 2005 67 94% 97% --Raff JACC 2005 70 86% 95% 12%

Diagnostic Accuracy of 64- slice MDCT

Maximum Intensity Projection RCA 3D VRT LCX and RCA

Occlusion 1st diagonal branch

Multiplanar Reconstruction

Limitations

TECHNICAL-- Calcium- Motion - Heart Rate

CONCEPTUAL- Contrast, X-ray- Sinus rhythm- No intervention

- decrease number of purely diagnostic invasive selective coronary angiograms- complimentary to stress testing- improve early triage of patients with acute chest pain

Potential Clinical Applications

Study Designearly risk stratification in the ED

decision to admit to hospital

MDCT

standard clinical care (blinded to MDCT)

discharge diagnosis

Test Raw Data

Overall

Sensitivity 5/5 1 (0.49, 1)Specificity 26/35 0.74 (0.57,0.88)Accuracy 31/40 0.78 (0.62, 0.89)PPV 5/14 0.38 (0.13, 0.65)NPV 26/26 1 (0.87, 1)DOR 286

Overall Diagnostic Accuracy of MDCT (>50% stenosis) vs. ACS

outcome

Patient without ACSPatient without ACS

43 year old female, 3 hours of substernal chest pain radiating to the back, negative initial Troponin and CK-MB, ECG: sinus bradycardia

• Patient with crushing chest pain• now relieved (Nitro)• Borderline ST- Elevation• No biomarker elevation

Patient with ACSPatient with ACS

LAD Occlusion

LCX Anomaly and Stenosis

Perfusion Defect

Potential Impact on Decision Making

Pretest Probability

Posttest Probability

P-value

ACSACS 0.44±0.39 0.79±0.28 0.03No No ACSACS

0.28±0.21 0.05±0.07 0.0001

Decrease average LOS in patients without ACS by 22 hours per patient

- decrease number of purely diagnostic invasive selective coronary angiograms- complimentary to stress testing- improve early triage of patients with acute chest pain- detect coronary anomalies

Potential Clinical Applications

Anomalous Right Coronary Artery

- decrease number of purely diagnostic invasive selective coronary angiograms- complimentary to stress testing- improve early triage of patients with acute chest pain- detect coronary anomalies- determine bypass patency

Potential Clinical Applications

• High sensitivity and specificity for arterial conduits and venous grafts• Limitations: distal Anastomosis in small vessels, metallic clips

Martuscelli Circulation 2004

Bypass Graft Patency

- decrease number of purely diagnostic invasive selective coronary angiograms- complimentary to stress testing- improve early triage of patients with acute chest pain- detect coronary anomalies- determine bypass patency- improve risk predicition/ change definition of CAD

Potential Clinical Applications

MPR of LAD in Cross SectionThin MIP

Detection of Plaque

Sensitivity 82%, Specificity 88% Achenbach et al. Circulation 2004

r = 0.64, p < 0.001

Moselewski et al. AJC 2004

Plaque Area

Potential to detect and quantify coronary plaque

Plaque Composition

Potential to discriminate calcified and non- calcified plaque

Leber et al JACC 2004

SummarySummary

• Cardiac CT is a fast robust and highly reproducible noninvasive test

• Lots of promise that it may change and improve management of patients with suspected or known CAD But no data available yet

• Direct information on the presence and extent of CAD (stenosis and plaque), LV function and perfusion

MGH Cardiac CTA 2005MGH Cardiac CTA 20051. Core Lab for US Multi-center Trial on the Detection

of Coronary Artery Stenosis with >1000 Patients2. Cardiac CT for early triage in Patients with Acute

Chest Pain 3. Core Lab for Siemens Multi-center Trial IVUS vs.

MDCT4. Non-Calcified Plaque (FHS) in Patients with Family

History of premature CAD (Framingham) 5. Correction of Image Degradation in cardiac CT

Thank you

Thank you