Cardiac CT Emerging Role and Current Indications

Cardiac CT Emerging Role and Current Indications Dr. Felix Keng MBBS, FRCP (Lond), FAMS, Dip CBNC, Dip CBCCT, MMed (Int Med), FAPSC Director, Nuclear Cardiology National Heart Centre, Singapore Adjunct Assistant Professor YLL School of Medicine National University of Singapore http://humanhealth.iaea.org

National Heart Centre, Singapore 2013

Hybrid Imaging Is EXCITING http://humanhealth.iaea.org

Hybrid Intervention / Surgery Is EVEN more EXCITING http://humanhealth.iaea.org

Stress Myocardial Perfusion Imaging (Nuclear SPECT) NHC 1984-2010 320 MDCT 16 MDCT Cardiac MRI 64 MDCT http://humanhealth.iaea.org

MPI Usage in the World http://humanhealth.iaea.org

Myocardial Perfusion & Viability Imaging in 2010 Nuclear Perfusion/Viability Imaging (SPECT/PET) ECHO/Contrast Perfusion & Viability CT Perfusion & Viability MR Perfusion & Viability

Fractional Flow Reserve Imaging in 2010 PET Perfusion Invasive Angiography (Pressure Wire) CTA FFR MR FFR http://humanhealth.iaea.org

Dr Felix Keng http://humanhealth.iaea.org

Siemens Philips GE Toshiba

Current Role of Cardiovascular MSCT Structural / congenital heart imaging Tumours, Pericardial disease Extra-cardiac / Great vessel imaging Peripheral vessel imaging Volumes and ejection fractions (cine + gating) Calcium Scoring Coronary artery imaging (contrast enhanced) Perfusion / viability imaging (contrast enhanced) CT in the ER (Triple Rule-Out) Pulmonary Vein mapping, thrombus imaging http://humanhealth.iaea.org

Other Roles? of Cardiovascular MSCT Plaque characterization, progression FFR by contrast CTA (cardiac hemodynamic assessment) Epicardial, Intrathoracic, Periaortic Fat assessment http://humanhealth.iaea.org

J Am Coll Cardiol Img, 2010; 3:19-28

Quantification of Pericardial / Intrathoracic Fat

http://humanhealth.iaea.org

Multi-Slice CT Technical Issues Cardiac motion Respiratory motion Radiation Contrast http://humanhealth.iaea.org

Imaging of the heart is technically Cardiac Motion Respiratory Motion difficult because:

Improvements of latest generation (?? slice vs 16 slice) MS CT Scanners Higher Rotation Speed: 330 ms Larger Number of Detectors:?? instead of 16 Allows: Higher temporal resolution: 83 ms instead of 250 ms Higher spatial resolution 0.5 x 0.5 mm (CMR 0.7 mm, Contrast Angiography 0.1 mm) Shorter breathholds: 3-5 sec instead of 20-30 sec http://humanhealth.iaea.org

MSCT in Congenital Heart Disease Excellent spatial resolution Morphology & relationship to other structures http://humanhealth.iaea.org

TA, AVSD, Hypoplastic RV

ASD, VSD

Co-Arctation of the Aorta

Patent Ductus Arteriosus

Miscellaneous Conditions http://humanhealth.iaea.org

Pericardial Pathology Pericardial Secondaries Absent Pericardium Pericardial Mesothelioma

Atrial Myxoma

RA Tumour

Thrombus LV Apical Thrombus LAA Thrombus

Aortic Dissection

50 year old male with Stanford Type B dissection from chronic cocaine use. The dissection flap begins at the level of the left subclavian artery and continues into the abdomen beyond the aortic bifurcation.

Pulmonary Embolism

Pulmonary Veins Location & Size of Pulmonary Veins Pre &/or Post AF Ablation TAPVD, PAPVD

Cardiac Veins Location, Size & Course Biventricular Pacemaker Implantation

LV Hypertrophy Imaging

Assessment of Cardiac Function

? Gold Standard for EF

CT in Valvular Heart Disease Excellent spatial & temporal resolution Ability to view the valve in 3 dimensions Assessment of valve morphology Assessment of valve area in valvular stenosis Pre & Post TAVI Paravalvular leaks Aortic & Mitral Valves http://humanhealth.iaea.org

Aortic Valve http://humanhealth.iaea.org

Unenhanced Cardiac CT Coronary Calcification (Calcium Scoring) Possible detection of soft plaques Possible detection of anomalous coronary origins & course Pulmonary Nodules (in FOV) Miscellaneous Findings (fish-bone, tumours, lymph nodes etc) Minimal radiation (<< 1 msv) http://humanhealth.iaea.org

Coronary Calcification http://humanhealth.iaea.org

Applications of MSCT Calcium Scoring http://humanhealth.iaea.org

Coronary artery calcium prevalence, 10-year event risk, and prevalence/risk ratio in asymptomatic men. Event risk and calcium prevalence are plotted against right axis, and prevalence/risk ratio is plotted against left axis. Prevalence/risk curve decreases with age, suggesting that although serious over-prediction will occur in the young, over-prediction will be only moderate in the elderly

Absence of Detectable Coronary Artery Calcification Using Electron Beam Computed Tomography (Negative Test) Does not absolutely rule out the presence of atherosclerotic plaque, including unstable plaque. Highly unlikely in the presence of significant luminal obstructive disease. Observation made in the majority of patients who have had both angiographically normal coronary arteries and EBCT scanning. Testing is gender independent. May be consistent with a low risk of a cardiovascular event in the next 2-5 years. http://humanhealth.iaea.org

Presence of Detectable Coronary Artery Calcification Using Electron Beam Computed Tomography (Positive Test) Confirms the presence of coronary atherosclerotic plaque. The greater the amount of calcification (i.e. calcium area or calcium score), the greater the likelihood of obstructive disease, but there is no one-to-one relation, and findings may not be site specific. Total amount of calcification correlates best with total amount of atherosclerotic plaque, although the true "plaque burden" is underestimated. A high calcium score may be consistent with moderate to high risk of a cardiovascular event within the next 2-5 years. http://humanhealth.iaea.org

Kaplan-Meier survival curves for 123 patients with CAC score <100 (5 hard events) and 165 patients with CAC score >100 (17 hard cardiac events). Patients with CAC scores >100 had significantly poorer outcome than patients with scores <100 (P <0.01).

He ZX. Circulation 2000;101:244-251

EBCT (top) and SPECT (bottom) images of asymptomatic subject who had high-risk CACS of 937. Circles define regions of coronary calcification. Upsloping (<1 mm) ST-segment depression occurred 9.0 minutes into ETT, which was terminated because of patient fatigue. Although Duke score was calculated as low risk (6.5), SPECT demonstrated large, reversible 48% perfusion defect (green) within distribution of all 3 major coronary arteries (COMP- SC) (bottom). This patient had severe 3-vessel disease on angiography and underwent CABG. PDS indicates perfusion defect size. http://humanhealth.iaea.org

http://humanhealth.iaea.org Value of a low CACS

http://humanhealth.iaea.org CACS + Normal MPI

Clinical Impact of CACS

Serial Calcium Scoring http://humanhealth.iaea.org

Effects of Statin therapy on the progression of coronary calcification (LM+pLAD) by EBCT A=Baseline B=12 months w/o statin C=12 months after statin therapy Achenbach, Circulation 2002;106:1077-1082

Achenbach, Circulation 2002;106:1077-1082 http://humanhealth.iaea.org

Coronary CTA Excellent NPV Excellent for anomalous coronary origin & course Excellent for AV fistulae Not so good for assessment of degree of coronary stenosis, especially when calcium score is high Radiation Load <1 msv to 20 msv, depending on retrospective/prospective gating, coverage etc http://humanhealth.iaea.org

Contrast Enhanced Coronary Artery Imaging LAD stenosis LAD stenosis

Contrast Enhanced Coronary Artery Imaging LAD stenosis

Study Type # of pts Achenbach 2001 Nieman 2001 Vogl 2002 Nieman 2002 Ropers 2003 Coronary Artery Disease Results % of evaluable segments evaluable segments Sensitivity all segments Specificity 4 64 68 % 91% 58 % 84% 4 35 73 % 81% - 97% 4 64 66 % 73 % - 99% 16 59 99 % 95 % 95 % 86 % 16 77 88 % 92% 73 % 93% Overall 87 % 91% http://humanhealth.iaea.org

Coronary Artery Disease Results Study Accuracy 2008( 50%) Accuracy 2008( 70%) Specificity Type # of pts Sensitivity PPV NPV 64 230 95 % 83% 64 % 99% 64 230 94 % 83% 48 % 99% Overall 94 % 83 % 56 % 99% http://humanhealth.iaea.org

Detection of Coronary Artery Disease One problem remains: calcification.

Role of CTA in CTO Extent of CTO Guide to intervention length, direction, degree of calcification http://humanhealth.iaea.org

Prognostic Significance of CTA

Usefulness of CTA

AORTA AND RENAL VESSELS http://humanhealth.iaea.org

ILIAC ARTERY STENOSIS http://humanhealth.iaea.org

PERIPHERAL ARTERIES

Characterization of myocardial infarction Contrast-enhanced chest MSCT reveals an infarct zone as a non-contrast-enhancing area w/i the posterolateral wall and both papillary muscles. The subject had an acute lateral MI on ECG and had acute PTCA w/i 1 hour of onset of chest pain http://humanhealth.iaea.org

A 49-year-old man with inferior acute myocardial infarction. Contrast-enhancement spiral CT was performed 2 days after successful direct PTCA. In addition to transaxial (axial) images, vertical long-axial (VLA) and short-axial images were obtained (a). LDA is evident in endocardial side of higher inferior wall, where both wall motion and systolic thickening are poor (arrows). Three days after PTCA, dual SPECT with 99mTcpyrophosphate (PYP) and 201Tl was performed. Superimposed images of PYP (red) and Tl (green) are also demonstrated (b). ED indicates end diastole; ES, end systole.

An 85-year-old woman with anteroseptal acute myocardial infarction. Contrast-enhancement spiral CT (CE-CT) started at 50 seconds of injection of contrast material (1.2 ml/s, 100 ml total) clearly demonstrates lower-density area (LDA) in anteroseptal wall, where neither wall motion nor systolic thickening was observed (a). With Gd-DTPA enhanced T1-weighted imaging, abnormal enhancement of anteroseptal wall is evident that corresponds to LDA of CT (b). 99mTcpyrophosphate (hot scan; PYP) depicts a hot lesion in anteroseptal wall, where deficient 201Tl accumulation was demonstrated with dual SPECT. Superimposed images of PYP (red) and Tl (green) are also demonstrated (c). Same patient as above. Seven days after successful PTCA, 3-phase dynamic spiral CT was performed. Data acquisition was started at 50 seconds, 3 minutes, and 8 minutes of injection of contrast material (1.2 ml/s, 100 ml total). In 50-second images, area of anteroseptal AMI is demonstrated as lower-density area (arrows, top row). In 3-minute images, AMI area was partially enhanced peripherally (arrows, middle row). In 8-minute images, whole AMI lesion is depicted as higher-density area than non-infarcted left ventricular wall (arrows, bottom row). http://humanhealth.iaea.org

Core 320 Study http://humanhealth.iaea.org

MSCT in Assessment of Coronary Stents http://humanhealth.iaea.org

Imaging in Stented Coronary Arteries More difficult due to hyper-enhanced signals from the coronary stents, thus in-stent restenosis can be missed Stents with bigger holes & diameters easier to image Contrast enhanced imaging useful to look for ISR in larger stents (> 3mm) Use of stent kernels further improve assessment http://humanhealth.iaea.org

Axial source and volume rendered images of the plad using end diastolic data in enhanced MSCT, showing a stent in the plad, and no evidence of restenosis. Correlation with coronary angiography http://humanhealth.iaea.org

Left Main Rapamycin-Coated Stent Multislice spiral CT coronary angiogram. The 2-D curved multiplanar reconstruction (A) depicts the entire course of the left main and left anterior descending coronary artery (LAD). No neointimal hyperplasia was noted within the struts of the stent (arrow). Cross-section of the stent in the inset (B). The exterior shape of the stent (arrow) can be observed on the volumerendered representation (C) and can be highlighted by altering the settings (D).

MSCT images. A, CT axial scan through the aortic root showed 2 stents in the mid left anterior descending (LAD); total length was 23 mm (dotted line) with a 3-mm overlapping segment (solid line). B, 3-D rendering of the heart and coronary arteries with manual segmentation of cross-sectional images. Left coronary system can be identified. LMCA indicates left main coronary artery; LCx, left circumflex; 1stD, 1st diagonal branch; and GCV, great cardiac vein. The stented segment (arrow) is localized in the mid LAD.

MSCT after Coronary Artery Bypass Grafting http://humanhealth.iaea.org

Imaging Post CABG Increased coverage required, resulting in more radiation load & contrast Surgical clips may cause artifacts Venous grafts are more easy to image as they move less and are of larger caliber Native vessels usually difficult to image because of heavy calcification and frequent complete occlusion http://humanhealth.iaea.org

LIMA to LAD

SVG to OM1

SVG to RPDA

Native LAD

Native LCx

Native RCA

Hybrid Imaging / Fusion Cardiology http://humanhealth.iaea.org

SPECT CT.

Cardiac CACS/CTA Appropriateness Use Criteria 2010 http://humanhealth.iaea.org

1.0 0.8 0.6 0.4 Positive test Acceptable C B Negative test 0.2 A Acceptable 0.2 0.4 0.6 0.8 1.0 Pretest probability

Myocardial Viability Siebelink et al (JACC 2001) demonstrated no difference in cardiac event free survival between PET and sestamibi SPECT determination of patient management in a prospective randomized trial. http://humanhealth.iaea.org

Myocardial Viability http://humanhealth.iaea.org

Myocardial Viability All Patients Medical Therapy Revascularization http://humanhealth.iaea.org

Conclusion With improving technology, the indications for cardiac CT will continue to grow New developments will reduce the risks involved with cardiac CT (radiation dose, contrast load) Diagnostic accuracy will improve as this technique matures Does not mean the demise of other imaging techniques, each modality has its strengths & weaknesses http://humanhealth.iaea.org

Conclusion Finding the correct test for the correct patient will remain a challenge as new techniques are introduced Decision as to which test to perform will be even harder in future, as more competing techniques are able to provide similar diagnostic and prognostic information The ideal situation would be to use multimodality imaging in a cost-effective & complementary manner, to improve the prognosis of cardiac patients http://humanhealth.iaea.org