Cardiac CT Emerging Role and Current Indications

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1 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

2 National Heart Centre, Singapore 2013

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5 Hybrid Imaging Is EXCITING

6 Hybrid Intervention / Surgery Is EVEN more EXCITING

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8 Stress Myocardial Perfusion Imaging (Nuclear SPECT) NHC MDCT 16 MDCT Cardiac MRI 64 MDCT

9 MPI Usage in the World

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

11 Fractional Flow Reserve Imaging in 2010 PET Perfusion Invasive Angiography (Pressure Wire) CTA FFR MR FFR

12 Dr Felix Keng

13 Siemens Philips GE Toshiba

14 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

15 Other Roles? of Cardiovascular MSCT Plaque characterization, progression FFR by contrast CTA (cardiac hemodynamic assessment) Epicardial, Intrathoracic, Periaortic Fat assessment

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

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

19 Quantification of Pericardial / Intrathoracic Fat

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25 Multi-Slice CT Technical Issues Cardiac motion Respiratory motion Radiation Contrast

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

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28 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 sec

29 MSCT in Congenital Heart Disease Excellent spatial resolution Morphology & relationship to other structures

30 TA, AVSD, Hypoplastic RV

31 ASD, VSD

32 Co-Arctation of the Aorta

33 Patent Ductus Arteriosus

34 Miscellaneous Conditions

35 Pericardial Pathology Pericardial Secondaries Absent Pericardium Pericardial Mesothelioma

36 Atrial Myxoma

37 RA Tumour

38 Thrombus LV Apical Thrombus LAA Thrombus

39 Aortic Dissection

40 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.

41 Pulmonary Embolism

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

43 Cardiac Veins Location, Size & Course Biventricular Pacemaker Implantation

44 LV Hypertrophy Imaging

45 Assessment of Cardiac Function

46 ? Gold Standard for EF

47 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

48 Aortic Valve

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51 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)

52 Coronary Calcification

53 Applications of MSCT Calcium Scoring

54 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

55 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.

56 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.

57 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).

58 He ZX. Circulation 2000;101:

59 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.

60 Value of a low CACS

61 CACS + Normal MPI

62 Clinical Impact of CACS

63 Clinical Impact of CACS

64 Serial Calcium Scoring

65 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:

66 Achenbach, Circulation 2002;106:

67 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

68 Contrast Enhanced Coronary Artery Imaging LAD stenosis LAD stenosis

69 Contrast Enhanced Coronary Artery Imaging LAD stenosis

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71 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 % 91% 58 % 84% % 81% - 97% % 73 % - 99% % 95 % 95 % 86 % % 92% 73 % 93% Overall 87 % 91%

72 Coronary Artery Disease Results Study Accuracy 2008( 50%) Accuracy 2008( 70%) Specificity Type # of pts Sensitivity PPV NPV % 83% 64 % 99% % 83% 48 % 99% Overall 94 % 83 % 56 % 99%

73 Detection of Coronary Artery Disease One problem remains: calcification.

74 Role of CTA in CTO Extent of CTO Guide to intervention length, direction, degree of calcification

75 Prognostic Significance of CTA

76 Usefulness of CTA

77 AORTA AND RENAL VESSELS

78 AORTA

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80 ILIAC ARTERY STENOSIS

81 PERIPHERAL ARTERIES

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83 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

84 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.

85 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).

86 Core 320 Study

87 MSCT in Assessment of Coronary Stents

88 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

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90 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

91 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).

92 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.

93 MSCT after Coronary Artery Bypass Grafting

94 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

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97 LIMA to LAD

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99 SVG to OM1

100 SVG to RPDA

101 Native LAD

102 Native LCx

103 Native RCA

104 Hybrid Imaging / Fusion Cardiology

105 SPECT CT.

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109 Cardiac CACS/CTA Appropriateness Use Criteria

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111 Positive test Acceptable C B Negative test 0.2 A Acceptable Pretest probability

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140 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.

141 Myocardial Viability

142 Myocardial Viability All Patients Medical Therapy Revascularization

143 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

144 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

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