David M Isaacs, DO Rotating Resident at


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David M Isaacs, DO Rotating Resident at

  1. 1. David M Isaacs, DO Rotating Resident at William Beaumont Hospital Department of Nuclear Medicine Cardiac Anatomy utilizing CT Angiography
  2. 2. Objectives Examine the need for Coronary Anatomy Imaging using CT Angiography (CTA) Explore the basic Technique and dose of Coronary CT Angiography (CCTA) Examine the different reconstruction algorithms Detail the Coronary Anatomy utilizing CCTA Examine Cardiac CTA for imaging veins and other heart structures Briefly review recently published data regarding clinical applications of CCTA
  3. 3. Background More than 5 million patients with acute chest pain present to emergency departments in the United States each year Patients who are at highestrisk for adverse outcomes derive the greatest benefit from glycoproteinIIb and IIIa inhibitor therapy and early revascularization By contrast, patients at low risk may be discharged withouta long-term effect on their risk of death or myocardial infarction
  4. 4. Background The term acute coronary syndrome (ACS) describes clinical manifestationsof acute myocardial ischemia induced by coronary artery disease The rate of missed diagnosis of acute coronary syndromes,which remains unacceptably high (2%–4%), is associatedwith a twofold increase in mortality This factorcontributes to a low threshold for hospital admission of patientswith chest pain by emergency department physicians. Consequencesof a missed acute coronary syndrome, and resultant liabilityissues (20% of emergency department malpractice dollar losses), andmore than 2 million patients with acute chest pain are unnecessarily admitted to the hospital
  5. 5. Background Short examination times of approximately 5 minutesand robust image quality, multidetector cardiac CT constitutesa highly attractive approach for initial work-up in the emergencydepartment setting.
  6. 6. Patient Selection and Preparation Contraindication history of severeallergic reaction to an iodinated contrast material impairedrenal function (creatinine level of > 1.5 mg/dL) Ideal Patients: Have a normal sinus rhythm, Targeted heart rateof less than 65 beats per minute during image acquisition Heart rate should bemeasured during a breath-holding test to determine whether theadministration of a ß-blocker is necessary heartrate often decreases by 5–10 beats per minute during thefirst few seconds of a postinspiration breath hold ß-blocker (eg,5–20 mg of metoprolol) immediately before the CT examination
  7. 7. A Standard CT Protocol 1. Localization:  projectionalanteroposterior topographic scan of the chest.  Theimaging volume should extend from 1–2 cm below the carinato the bottom of the heart. 1. Determination of Contrast Agent Transit Time:  15 mL of the contrast agent, immediately followedby 40 mL of saline, is injected at a flow rate of5 mL/sec  Scanning is initiated 10 seconds after the start ofthe contrast medium injection  Axial images are acquired atthe level of the aortic root (10-mm collimation) at intervalsof 2 seconds and are instantly displayed 3. Data Acquisition:  Images are acquired in helical mode during injection of 60–100mL of the contrast agent  followed by 40 mL of saline solution, at a rate of 4–5 mL/ sec
  8. 8. A Standard CT Protocol  The short scan duration of 12 to 15 seconds permits a breath-hold imaging duration that can capture homogenous contrast opaci cation around the narrowfi peak of contrast enhancement  Optimal imagequality usually can be achieved in diastole (starting at approximately 65% of the R-R cycle)  Images typically reconstructed with 1-mm section thicknessand a 0.5-mm overlap at 16-section multidetector CT and witha 0.75-mm section thickness and 0.4-mm overlap at 64-sectionmultidetector CT  Nearly isotropicresolution (voxel size, 0.4 x 0.4 x 0.6 mm) permits reformattingof images in any arbitrary plane without a significant lossof image information.
  9. 9. ECG triggering and gating ECG triggering: the scanner acquires data only for a de ned period after thefi signal from the R wave of the ECG trace. “step and shoot” scan technique an image is acquired every second heartbeat to allow table translation between image generation ECG gating:  the scanner acquires data in a nonstop, helical mode while an independent ECG trace is generated at the same time Images are acquired both during systole and diastole
  10. 10. ECG triggering and gating To summarize: TriggerTrigger GatingGating ECG to acquire data and is prospective ECG to reconstruct data and is retrospective “Step and shoot” Continuous coronary calci cationfi scoring aortic root imaging required for coronary artery CTA
  11. 11. Multiplanar Imaging- Key= Temporal Resolution The advent of multidetector CT (MDCT), particularlywith scanners having 64 or more detectors, has continued to improve temporal resolution (TR).  TR may be thought of as the “shutter speed” of the scanner and is the key to recent advancements in MDCT technology. Temporal resolution in the region of 100 msec is required to create relatively motionless images of the beating heart Thus, the heart and coronary arteriesare routinely imaged as a motion-free volume of data and is reconstructed in multiple formats: Multiplanar reformation(MPR), maximum intensity projection (MIP), volume rendering(VR), curved reformation, and cine imaging
  12. 12. Multidetector CT Postprocessing Techniques Multiplanar Reformation • MPR is the basic tool used to interpret cardiac CT angiographicstudies • Data from specific phases of the cardiac cycle are retrospectively referenced to the electrocardiogram for reconstruction • The workstationallow images of the heart and coronary arteries to be manuallyrotated for optimal evaluation of the cardiac anatomy • Automaticallyorient data sets along the cardiac axes andinto the traditionally used cardiac planes (ie, short-axis,horizontal long-axis, vertical long-axis)
  13. 13. Multidetector CT Postprocessing Techniques Maximum Intensity Projection Technique that takes the highest-attenuationvoxel in a predetermined slab of data and projects it from theuser toward the viewing screen, resulting in a two-dimensionalimage. similar to traditional angiograms, whichdisplay intraluminal opacity values can allow quickassessment for significant coronary artery stenosis limitation of MIP imagesis that they lack depth and spatial information
  14. 14. Multidetector CT Postprocessing Techniques Volume Rendering 3D technique in which the CT attenuation values foreach voxel can be assigned a specific color, thereby producingan overall image of the heart only true 3D techniqueand provides the depth and spatial information that is lackingwith MIP facilitate surface evaluationof the heart and coronary arteries useful for evaluatingcomplex anatomy, including coronary artery anomalies, bypassgrafts, and fistulas easily understandableformat for referring physicians useful also for surgical planning
  15. 15. Multidetector CT Postprocessing Techniques Curved Reformation Coronary arteries are often tortuous, accurateevaluation requires assessment of the entire vessel along itscenter line Curved reformatted images provide this capabilityby sampling a given volume (ie, artery) along a predefined curvedanatomic plane Most useful for depicting the lumen of a coronaryartery from its ostium to its distal end. Is especially helpful in patients with bypass grafts and highlytortuous coronary arteries
  16. 16. Multidetector CT Postprocessing Techniques Cine Imaging examine the motion and physiologic featuresof cardiac structures such as the LV and cardiac valves data from the heart and coronaryarteries are typically reconstructed at specific points duringthe cardiac cycle, ie. Examine certain anatomy during systole and diastole particularlyuseful for examining LV wall motion and wall thickening and for assessing valve motion in multiple planes reconstructionof the cardiac data during both systole and diastole allows determination of quantitative LV functional parameters, includingend- diastolic and end-systolic ventricular volumes, stroke volume,and ejection fraction
  17. 17. Ventricular Function Left Ventricle Normal Function Right Ventricle Normal Function
  18. 18. Radiation Exposure at CT Coronary Angiography  ECG-controlled dose modulation technique is used to reducethe tube current during systole, The effective radiation doseis 6.7–7.6 mSv in men and 8.1–9.2mSv in women For 64-section scanners, theradiation dose at cardiac CT is 6.9–11.1 mSv Withouttube current modulation, the radiation dose is estimated tobe approximately 16–20 mSv By comparison, a mean effectiveradiation dose of approximately 5 mSv is incurred at selectivecoronary angiography  RadioGraphics 2006;26:963-978  The estimated total bodyradiation exposure after a 16 slice MDCT coronary angiogram is 2 to3 times the average exposure from a diagnostic catheterization but similar or lower than the exposure from a rest-stress myocardial scintigraphic study
  19. 19. Coronary Arteries By general consensus, the coronary artery tree is divided into 17 segments, according to the AHA system of classification
  20. 20. Coronary Anatomy- Segments  Axial CT image (0.75-mm section thickness) at the midventricular level shows a middle segment of the right coronary artery (RCA) and distal segments of the left anterior descending and left circumflex branches.  The latter is seen in the left atrioventricular groove, in close proximity to the great cardiac vein (GCV).
  21. 21. Coronary Anatomy- Segments  Axial MIP image (5-mm section thickness) at the level of the bottom of the heart shows a distal segment of the RCA at the origins of the posterior descending artery (PDA) and the posterior left ventricular (PLV) artery.  The posterior descending artery is seen in the posterior longitudinal sulcus, in close proximity to the middle cardiac vein (MCV).  A distal segment of the LAD also is visible.  This case demonstrates right coronary artery dominance in blood supply to the ventricles, a common finding (85%–90% of patients).
  22. 22. Y’all hold on, Here we go in…
  23. 23. Left Main Coronary Artery (LCA) Usually the first coronary artery seen (starting superiorly from its origin) Normally arises from the left sinus of Valsalva near the sinotubular ridge Courses posterior to the right ventricular outflow tract (RVOT), and bifurcates into the left anterior descending (LAD), and the left circumflex (LCX) branches. In about 15% of patients, a separate intermediate branch, or ramus intermedius (RI), also arises from the left main coronary artery
  24. 24. LCA Segmental Anatomy  5 = main artery,  6 = proximal segment of the left anterior descending (LAD) branch,  7 = middle segment of the LAD branch,  8 = distal segment of the LAD branch,  9 = first diagonal branch,  10 = second diagonal branch,  11 = proximal segment of the left circumflex (LCX) artery,  12 = first obtuse marginal branch of the LCX artery,  13 = middle segment of the LCX artery,  14 = second obtuse marginal branch of the LCX artery,  15 = distal segment of the LCX artery,  17 = intermediate branch
  25. 25. LCA segmental Anatomy  5 = main artery,  6 = proximal segment of the left anterior descending (LAD) branch,  7 = middle segment of the LAD branch,  8 = distal segment of the LAD branch,  9 = first diagonal branch,  10 = second diagonal branch,  11 = proximal segment of the left circumflex (LCX) artery,  12 = first obtuse marginal branch of the LCX artery,  13 = middle segment of the LCX artery,  14 = second obtuse marginal branch of the LCX artery,  15 = distal segment of the LCX artery,  17 = intermediate branch  The arrowhead in indicates the mid intermediate branch
  26. 26. LCA  VR image shows the LCA (black arrow) arising from the aorta and bifurcating into the proximal LCx artery (arrowhead) and the proximal LAD artery (white arrow). The LCA (black arrow) bifurcates into the left anterior descending (LAD) artery (white arrowhead) and the left circumflex (LCx) artery (black arrowhead). White arrow indicates the right coronary artery (RCA).
  27. 27. LCA LAD  The LAD artery courses anterolaterally in the epicardial fat of the anterior interventricular groove and supplies the majority of the LV  The LAD artery is divided into proximal, middle, and distalportions  The midportionof the LAD artery extends to the point where the artery formsan acute angle  The apical segmentrepresents the termination of the artery.  Oblique axial (top) and vertical long- axis (bottom) MPR images show the normal LAD artery (arrows) coursing in the epicardial fat of the interventricular groove toward the LV apex
  28. 28. LCA LAD Diagonal Septal The major branches of the LAD artery are the diagonal and septal perforating arteries. The diagonal branches course laterally and predominantly supply the LV free wall. The septal branches course medially and supply the majority of the interventricular septum, as well as the atrioventricular (AV) bundle and proximal bundle branch. Septal branches (black arrowheads) diagonal branches (white arrowheads) of the LAD artery
  29. 29. LCA LCx Divided into proximal and distal segments,based on the origin of the (usually large) obtuse marginal branches Courses in the left AV groove, giving rise to obtuse marginal branches --sometimes referred to as lateral branches Supply the LV free wall and a variable portion of the anterolateral papillary muscle Variably gives rise to posterolateral and posterior descending artery (PDA) branches supplying the diaphragmatic portion of the LV
  30. 30. LCA LCx Obtuse Marginals Oblique axial MPR (top) and VR (bottom) images show the LCx artery (black arrow) and obtuse marginal branches (white arrows).
  31. 31. LCA Ramus Intermedius  In approximately 15% of patients, a third branch, the ramus intermedius (RI) branch, arises at the division of the LCA, resulting in a trifurcation  When present, the RI branch courses toward the LV free wall, similar to that of a diagonal branch of the LAD artery. RI branch (arrow) arising between the LAD artery (black arrowhead) and the LCx artery (white arrowhead), resulting in a trifurcation of the LCA
  32. 32. Right Coronary Artery (RCA)  Normally arises from the right coronary sinus (CS) and courses in the right AV groove toward the crux of the heart  The proximal RCA extends from the ostium to a point halfwayto the acute margin of the heart  Approximately 50%–60% of patients, the first branch of the RCA is a conus artery  conus artery supplies the RV outflow tract (conus arteriosis) and forms the circle of Vieussens, an anastomosis with the LAD arterial circulation
  33. 33. RCA Segmental Anatomy  1 = proximal segment of the main artery,  2 = middle segment of the main artery,  3 = distal segment of the main artery,  4 = posterior descending branch,  16 = posterior left ventricular branch,  CB = conal branch,  SN = sinonodal branch
  34. 34. RCA Segmental Anatomy  1 = proximal segment of the main artery,  2 = middle segment of the main artery,  3 = distal segment of the main artery,  4 = posterior descending branch,  16 = posterior left ventricular branch,  CB = conal branch,  SN = sinonodal branch  AM = acute marginal branch
  35. 35. RCA Branches  Sinoatrial nodal artery arises from the RCA in 58%; in the remaining patients (42%), it arises from the LCx artery  Multiple ventricular branches arise from the RCA, the largest of which is called the acute marginal branch MPR images (top,left) and VR image (right) show the RCA (black arrow) and its branches. In this case, the conus artery (long arrow) arises from the aorta. White arrow in top and arrow in left indicate the acute marginal branch, arrowhead in right indicates the sinoatrial nodal branch
  36. 36.   Dominance The coronary artery that gives rise to the PDA and posterolateralbranch is referred to as the "dominant" artery RCA is dominant in about 70% of cases LCAin 10% of cases, supplying the entireLV Remaining cases (20%), the RCA and LCA arecodominant; that is, portions of the LV diaphragmatic wall aresupplied by both the RCA and the LCx artery The lengthof the distal RCA is inversely proportional to the length ofthe LCA along the inferior aspect of the heart
  37. 37. Dominance A right-dominant system: PDA (white arrowhead) arising from the RCA (black arrowhead). A posterolateral branch (arrow) is also seen. A codominant system, with the inferior myocardial surface supplied equally by the RCA and the LCx artery
  38. 38. Normal Coronary Artery Diameter The average size varies with gender (approximately3 mm in females and 4 mm in males) each coronary artery also vary, ranging from 5 mm (LCA in males) to 2 mm (PDA in females) CCTA guidelines have not been published, and the above are based on angiographic data. Focal abnormal dilatation to more than 1.5 times the diameterof an adjacent normal coronary artery is defined as an aneurysm
  39. 39. Normal Coronary Artery Diameter If the process is diffuse, it is known as ectasia . Either process is easily identified with cardiac CT angiography  VR images obtained in an adolescent with Kawasaki disease show a focal RCA aneurysm (arrowhead).
  40. 40. Cardiac and Pulmonary Veins Excellent for imaging the Coronary Sinus (CS) and cardiac veins The most constant structure is the CS itself,which runs along the inferior aspect of the heart in the AVgroove before emptying into the RA 1st branchof the CS is the middle cardiac vein, which courses in the posterior interventriculargroove from base to apex Next two branches are theposterior vein of the LV and the left marginal vein The CS becomes the great cardiac vein
  41. 41. Cardiac Veins CS (arrowheads) coursing along the inferior surface of the heart and emptying into the RA. In this case, the posterior vein of the LV (white arrow) is prominent and the left marginal vein is absent. Black arrow indicates the posterior interventricular vein VR image shows the great cardiac vein (arrowheads) coursing in the left AV groove.
  42. 42. Cardiac Veins Variability in the cardiac veins is usually due to absence ofeither the left marginal vein or the posterior vein of the LV. Whys is this relevant? Patients treated with cardiac resynchronizationtherapy typically undergo implantation of an automatic cardioverter-defibrillator for the treatment of heart failure, ideally with a transvenous approach. If no suitablevein is present in which to place the LV pacer lead with a transvenousapproach, surgical placement may be necessary
  43. 43. Pulmonary Veins  The PVs also receive significant attention because of ablation therapy.  LA musclecan extend into the venous ostia, and ectopic electrical foci originating at this site may be the cause of atrial fibrillationin a significant number of patients  If additional PVs are present,it is important that they be described prior to ablation. Theyare typically single and occur more commonly on the right side Middle PVs arising on the right side havea stronger association with atrial fibrillation
  44. 44. Atrial Appendages Patients with atrial fibrillation may develop thrombus in the LA appendage, a condition that can be evaluated with multidetectorCT prior to PV ablation >97%, the LA appendageshave pectinate muscles measuring greater than 1 mm LA appendage arises from the superolateral aspect of theLA and projects anteriorly over the proximal LCx artery
  45. 45. Atrial Appendage  normal RA appendage (arrow) and pectinate muscles  Vertical long-axis MPR image shows the normal LA appendage (arrow). The linear filling defects in the appendage represent normal pectinate muscles
  46. 46. Cardiac Valves  The four cardiac valves are routinely imaged during cardiacCT angiography, and their motion and morphologic characteristics also assessed at all cardiac CT angiographic examinationswith reconstructed and cine images.  The MV is composed of twoleaflets, the anterior and posterior leaflets; the other valvesnormally have three leaflets  Calcification of the MVannulus is a common abnormality that makes identification of the annulus possible  The papillarymuscles with their chordae tendineae arealso a component of the MV apparatus  The tricuspid valve separates the RA from the RV and is connected to the RV
  47. 47. Cardiac Valves •The aortic valve separates the LV outflow tract from the ascendingaorta. • It is composed of an annulus, cusps, and commissures. • No papillary muscles or chordae tendineae are associated withthe aortic valve AO valve: Cusps are the right coronary cusp (white *), the left coronary cusp (black *), and the noncoronary cusp (box)
  48. 48. Pericardium  Normally paper thin, measuring 2 mm or less  It is composed of two layers, the parietal layer andthe serous layer  The pericardium lining the surface of the heart is knownas the visceral pericardium, or epicardium.  It is important to be aware of the more common recesses andsinuses to distinguish them from lymphadenopathy or abnormal soft tissue
  49. 49. Not too much more.. Now some practical stuff.
  50. 50. Cardiac CT Angiography A Brief Look at PracticalApplications
  51. 51. Relevant Findings at Cardiac CT  Datafrom clinical trials in patients with ACSindicate that the detection of a significant stenosis may helpimprove risk stratification.  Most patients with unstable angina or non–ST-segment-elevationmyocardial infarction (80%–94%) – show a significant coronarystenosis at coronary angiography  Several studies with intravascular ultrasonography(US) demonstrated that many coronary atherosclerotic lesionsthat cause acute events have a distinct morphology that includesa thrombus, a small residual vessel lumen, a greater plaqueburden, and more pronounced positive remodeling  So what does all this mean to CCTA?
  52. 52. Show me the Money $$  The detection and characterization ofdetection and characterization of coronary atheroscleroticcoronary atheroscleroticplaqueplaque may aid in the identification of patients at risk foran acute coronary syndrome  The primary use for coronary multidetector CT may be in patients with an intermediate likelihood of experiencing an acute coronary syndrome
  53. 53. Coronary Plaques The sensitivity of CCT is greater for calcified (94%) than for mixed (78%) or soft (53%) plaques and is mostly limited to large-calibervessels Compared with intravascular ultrasound, CCT tends to underestimate the noncalcified plaque volume but to overestimatethe calcified plaque volume
  54. 54. Stenosis of the Widow Maker  Significant stenosis of the left anterior descending artery in a 67-year-old patient with unstable angina and multiple risk factors (history of premature coronary artery disease, hypercholesterolemia, hypertension) but negative results at testing for biochemical markers and no acute ECG changes.  (top) Axial thin-section (5-mm) MIP image from a 64 MDCT shows a significant luminal narrowing (arrowhead) in the middle segment of the artery.  (bottom) Selective coronary angiogram demonstrates an eccentric high-grade (94%) stenosis (arrowhead).
  55. 55. CABG It is of proven value in evaluating the patency of bypass grafts But, limited in evaluating the anastamosis and small- vessel disease beyond the anastamosis
  56. 56. Recent Data  The results a large multicenter study published in JAMA in 2006 (n=238)demonstrated a higher numberof false-positive and nonevaluable segments using a 16 MDCT  Of 1629 nonstented segments larger than 2 mm indiameter, there were 89 (5.5%) in 59 (32%) of 187 patients withstenosis of more than 50% by conventional angiography. Of the1629 segments, 71% were evaluable on MDCT  sensitivity for detectingmore than 50% luminal stenoses was 89%; specificity, 65%; positivepredictive value, 13%; and negative predictive value, 99%  They concluded that this may be useful in excludingcoronary disease in selected patients in whom a false-positiveor inconclusive stress test result is suspected.  Garcia M. et al. Accuracy of 16-Row Multidetector Computed Tomography for the Assessment of Coronary Artery Stenosis. JAMA. 2006;296:403-411
  57. 57. More Recent Data  Using a 64 MDCT Sensitivityfor the detection of stenosis <50%, stenosis >50%, andstenosis >75% was 79%, 73%, and 80%, respectively, and specificitywas 97%  Leber A. et al. Quantification of Obstructive and Nonobstructive Coronary Lesions by 64-Slice Computed Tomography. J Am Coll Cardiol, 2005; 46:147-154  A large Meta-analysis of the literature included 38 studies demonstrated overall that 64 spiral CT has significantlyhigher specificity and PPV on a per-patient basis compared with 16-sectionCT for the detection of greater than 50% stenosis of coronary arteries.  Hamon M. et al. Coronary Arteries: Diagnostic Performance of 16- versus 64-Section Spiral CT Compared with Invasive Coronary Angiography—Meta-Analysis(Radiology 2007;245:720-731.)
  58. 58. SPECT MPI As a comparison Findings of multiple studies have shown sensitivity ranging from90% to 100%, specificity from 60% to 78%, and negative predictivevalue from 97% to 100% at radionuclide perfusion imaging for ACSif single photon emission computed tomography (SPECT) imaging isused  White C, Kuo D. Chest Pain in the Emergency Department: Role of Multidetector CT. Radiology 2007;245:672-681.
  59. 59. Example Case  CT and radionuclide perfusion images in a 67-year- old man who presented to the ED with atypical chest pain.  (a) Two-dimensional map of the coronary arteries from a CT triple rule-out protocol shows substantial calcification with areas of stenosis in the left anterior descending (LAD) and right coronary arteries (RCA). AcuteMarg = acute marginal, D1 = first diagonal, D2 = second diagonal, LCX = left circumflex artery.  (b) Curved planar reconstructed view of right coronary artery demonstrates substantial calcified and noncalcified plaque causing luminal narrowing (arrows).  (c) Radionuclide perfusion image shows a defect (arrow) in the inferior myocardial wall.
  60. 60. Calcium Scoring Most widely used measure of calcium burden is the calciumscore (often known as the Agatston score), which is based onthe radiographic density–weighted volume of plaques withattenuation values of greater than 130 Hus Several studieshave indicated that the calcium score provides prognostic informationindependent of conventional risk factors greater than 300 was associated witha significant increase in cardiac events  Radiology 2005;235:415-422.) © RSNA, 2005 Cardiac Imaging  Coronary Artery Stenoses: Detection with Calcium Scoring, CT Angiography, and Both Methods Combined1  George T. Lau
  61. 61. Diagnostic Value of Coronary Calcification Findings  Resultsof these studies demonstrate a high negative predictive valueof the absence of coronary calcifications for acute coronary syndrome  The characteristics of coronary calcification in patients with stable angina were found to differ from thosein patients with unstable angina Electron-beam CT was used to evaluate coronary arteries in all patients in the three studies listed 1999-2000. •However, the diagnostic value of a finding of coronary calcification is controversial. • In a studyby Greenland 2004, 14% of events (myocardial infarction and death) were observed in patients in whom no evidence of coronary calcification was found at CT
  62. 62. Bottom Line  Appropriate indications forCCT are as follows:  chest pain: intermediate pretest probabilityfor CAD (ECG cannotbe interpreted or patient is unable to exercise),persistentchest pain after equivocal stress test, or suggestionof coronaryanomalies;  acute chest pain in emergency department:intermediate pretestprobability for CAD (no changes in ECGand negative enzyme testresults);  pulmonary vein isolation,biventricular pacemaker implantation,or coronary arterial mappingin repeat cardiac surgery;  cardiac masses or pericardial diseasewith technically limitedimages from echocardiogram, MRI, or transesophageal echocardiography;  complex congenital heartdisease: assess anatomy.  Gonzalez SP, Sanz J, Garcia M. Cardiac CT: Indications and Limitations. Journal of Nuclear Medicine Technology. Vol 36, Num 1, 2008 18-24.
  63. 63. Bottom Line  Uncertain indications for CCT are as follows:  chest pain: intermediatepretest probability for CAD (ECG canbe interpreted and patientis able to exercise) or low or high pretest probability forCAD (no changes in ECG and negativeenzyme test results);  acutechest pain: rule out obstructive CAD, aortic dissection,andpulmonary embolism if the pretest probability for one ofthem is intermediate;  high risk of CAD in asymptomatic patients;  chest pain after revascularization (percutaneous interventionor coronary artery bypass grafts): evaluate bypass grafts orhistory of revascularization with stents;  intermediate perioperativerisk of cardiac events in patientsundergoing intermediate-or high-risk noncardiac surgery;  valvular disease (nativeor prosthetic valves) with technicallylimited images from ECG,MRI, or transesophageal echocardiogram.  Gonzalez SP, Sanz J, Garcia M. Cardiac CT: Indications and Limitations. Journal of Nuclear Medicine Technology. Vol 36, Num 1, 2008 18-24.
  64. 64. References:  O’ Brien J, Srichai M, Hecht E. Anatomy of the Heart at Multidetector CT: What the Radiologist Needs to Know. RadioGraphics 2007;27:1569-1582  Lawler L. CT scanning of the coronary arteries: How to do it and how to interpret it. Applied Radiology. Volume: 34 Number: 10 October 2005.  Hoffman U, Pena A, Cury R. Cardiac CT in Emergency Department Patients with Acute Chest Pain1 RadioGraphics 2006;26:963-978.  Lau G. Et al. Coronary Artery Stenoses: Detection with Calcium Scoring, CT Angiography, and Both Methods Combined1 Radiology 2005;235:415-422.  Mollet N, Cademartiri F, Van Meighem C. et al. High-Resolution Spiral Computed Tomography Coronary Angiography in Patients Referred for Diagnostic Conventional Coronary Angiography Circulation. 2005;112:2318-2323.
  65. 65. Thank YOU for your Attention !!!