The use of Cardiac CT and MRI in Clinical Practice Matthew W. Martinez, MD Assistant Professor of Medicine LVPG - Lehigh Valley Heart Specialists Lehigh Valley Health Network Oct. 3, 2009
DISCLOSURE Relevant Financial Relationship(s) None Off Label Usage None
Learning Objectives Review basics of cardiac MRI and CTA Review utility of cardiac CT and MRI in clinical practice Clinical cases
Noninvasive Tests for the Diagnosis of Coronary Artery Disease TMET SPECT Echo PET CT MRI
Cardiac MRI Black-Blood (Spin-Echo) White-Blood SSFP Delayed Enhancement Still Images Morphology Edema Cine Imaging Morphology and function Still Images Delayed Enhancement
SSFP = 2D echo
Delayed Enhancement-MRI Images obtained 10-15 15 minutes post-contrast (Gd( Gd) Normal myocardium Black * Necrosis/scarring/inflammation Hyperenhanced Image in Press Nature of Clinical Practice
Abundance of validation data in animal models Dog with near- transmural infarct Visible on SPECT and DE-MRI 3 dogs with subendocardial infarcts Visible on DE-MRI only Infarct size by MRI Delayed Enhancement CP1302151-4
Hyperenhancement Patterns Ischemic Subendocardial infarct Nonischemic Mid-wall HE Epicardial HE Transmural infarct Idiopathic dilated cardiomyopathy Myocarditis Hypertrophic cardiomyopathy Right ventricular pressure overload Sarcoidosis Myocarditis Anderson Fabry disease Shah DJ et al: Magnetic resonance of myocardial viability
Mass RV Function Cardiomyopathies
Cardiac MRI Functional LVEF LV mass Wall Motion LV ESV LV EDV Analysis LV stroke volume RV ESV RV EDV RV Stroke volume RVEF Tissue characterization Infarct identification Infarct size Viability
Evaluation of Chest Pain Prognosis Viability Imaging ACS Function Infarct size Unstable Hemodynamics and Complications CP1210291-8
Functional LVEF LV mass Wall Motion LV ESV LV EDV Analysis LV stroke volume Cardiac MRI RV ESV RV EDV RV Stroke volume RVEF Tissue characterization Infarct identification Infarct size Viability Prognosis
Case 1 57-year year-old woman Sudden onset of achy, continuous, substernal, 8/10 chest pain Radiating to back Pain came on at rest Cardiac Risk Factors Never Smoker Hyperlipidemia (untreated) Sedentery Lifestyle Troponin 0.56, 0.5 (3h), 0.36 (6h)
Echocardiogram
Cardiac Catheterization
Cardiac Catheterization
Cardiac MRI
Cardiac MRI Acute MI
Importance of unrecognized Myocardial scar Aim: Assess the prognostic significance of unrecognized myocardial scar by MRI in patients without a history of MI 195 patients without known prior MI 1) Pts with unknown status of CAD referred for assessment of LV fxn,, scar 2) Pts with angiographic CAD referred for prediction of segmental wall motion after revascularization (22) 16 month follow-up Circulation, 2006
Case Presentation 2 History of Present Illness 46 year old man presents to ED, 6:30 AM with 10/10 chest pain Began 4:30 AM - Radiated to left arm No SOB, no n/v Feeling ill with episodic CP over past 2 weeks Past Medical History Hyperlipidemia at health fair Medications none Social History 30 pack year history, currently smokes 1 pack/week
Initial ECG
Angiography Results Troponin Elevation: Baseline 0.44 3 hr 0.48 6 hr 0.49
Cardiac MRI
Delayed Enhancement Myocarditis
Etiologies of Elevations of Cardiac Plaque rupture mediated necrosis STEMI nstemi Alterations in coronary vasomotor tone Coronary spasm Subarachnoid hemorrhage Intracranial hemorrhage Apical Ballooning Syndrome Transplant vasculopathy Troponins Sub-endocardial myocyte necrosis CHF Hypertensive crisis Acute pulmonary embolism Tachycardia-mediated CHF, Pressure overload Volume-Pressure overload (renal failure, CHF, fluid resuscitation) Anemia Hypotension Aortic Stenosis and / or Regurgitation Hypertrophic Cardiomyopathy Amyloid heart disease
Problem Solving Tool Troponin is extremely sensitive for detecting myocardial cell necrosis 9-14% of patients who present with ACS will have normal or non-significant disease on coronary angiography This cohort of patients have been shown to have a poorer prognosis; potentially from clinical uncertainty (TACTICS-TIMI TIMI-18)
Development of CT MDCT 4-slice 1998 MDCT 16-slice 2002 MDCT 40-slice 2005 MDCT 320-slice 2008 DSCT 128-slice 2009 MDCT 8-slice 2001 MDCT 64-slice 2004 DSCT 64-slice 2006 2000 2010 2015
CT Scanning Minimally Invasive Angiography
Nuclear Cardiac Imaging Diagnostic Accuracy Imaging Modality # of Studies Patients Sen. (%) Spec. (%) Accuracy SPECT 99m Tc* > 45 ~7,000 83-86 86 73-75 75 83-86% 86% CTA* >20 ~2,000 83-94 77-92 89-92 92 GOLD Standard - Angiography
MDCT in Clinical Practice A Clinician s s Viewpoint Gold Standard Anomalous coronary vessels Coronary fistula, aneurysms Coronary Disease Great for ruling out CAD OK (but not great) for disease severity
Patient Population High Probability Intermediate Probability Low Probability Definite signs of CAD: Typical chest pain ECG changes & cardiac enzyme elevation Personal history of CAD
Patient Population High Probability Intermediate Probability Low Probability Indeterminate signs of CAD: Atypical chest pain Discordant symptoms & stress test results High risk factors & negative stress test Low risk factors & positive stress test Patient reluctant to have a cath
Patient Population High Probability Intermediate Probability Low Probability CTA
Patient Population High Probability Intermediate Probability Low Probability Doubtful signs of CAD: Worried well
Patient Population High Probability Intermediate Probability Low Probability? CTA?
Patient Population High Probability Intermediate Probability Low Probability CTA? CTA?
History 49yr female previously healthy 6+ months of dyspnea on exertion No personal history of hyperlipidemia, HTN, CAD, smoking, and family history Currently on no cardiac medications BMI = 36.
History Exercise Time: 7.3 minutes Test was stopped due to dyspnea and leg fatigue 32,736 (SBP x HR) Stress Echo with an area of anterior ischemia was noted from mid to the base ECG was negative
Appropriateness for CT
References supporting the use of coronary CTA following equivocal exercise sestamibi Schuijf, J., et. al, Relationship between Noninvasive Coronary Angiography with Multi-slice Computed Tomography and Myocardial Perfusion Imaging Journal of the American College of Cardiology; ; December 19, 2006. Rubinstein, R., et. al, Usefulness of 64-slice multidetector computed tomography in diagnostic triage of patients with chest pain and negative or nondiagnostic exercise stress test result American Journal of Cardiology 2007; 99: 925-929. 929. Danciu, S., et. al, Usefulness of multislice computed tomography coronary angiography to identify patients with abnormal myocardial perfusion stress in whom diagnostic catheterization could be avoided American Journal of Cardiology 2007; 100: 1605-1608. 1608. Dewey, M., et. al, Head-to-head comparison of multislice computed tomography and exercise electrocardiography for diagnosis of coronary onary artery disease European Heart Journal 2007; 28: 2485-2490. 2490.
Case 2 chest pain 55 y/o woman Substernal chest discomfort 2 mos Emotion and sometimes exertion Today 10 min chest and back pain at rest ED Postmenopausal Prior smoker >15 yrs ago No FH No meds Mild HTN
Exam: no murmur BP 142/88 Troponin: <.01 Creat: 0.8
Acute chest pain What do you want to know? Risk of acute event High Angio Low/inter Probability CAD Low Intermediate
What to Do? Sestamibi Stress Echo Coronary CTA
CTA vs Standard of Care in Chest Pain Chest pain Low risk 197 pts MSCT Normal Nondiag Severe Standard care Stress Nucs Stress Nucs HOME Angio HOME Goldstein JACC 2007 49:863-71
CTA 67% normal and discharged 9% severe CAD cath 24% needed further eval Length of stay: lowered by 43% 12.5 hrs vs 22.1 hrs Cost of care: lowered by 15% $1586 vs $1872 Goldstein JACC 2007 49:863-71
Conclusions Cardiac MRI EF, ESV, EDV, RV function, infarct size ICM vs DCM ACS Cardiac CT Excellent for exclusion of CAD in low to intermediate risk ED patients, equivocal stress test
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