Cardiac CT-CCTADr.Sahar Gamal El-Dr.Sahar Gamal El-

Din,CBCCTDin,CBCCTNational Heart InstituteNational Heart Institute

AgendaAgenda• IntroductionIntroduction

• Historical backgroundHistorical background

• IndicationsIndications

• ContraindicationsContraindications

• LimitationsLimitations

IntroductionIntroduction

• Cardiac CT and CCTA has emerged as Cardiac CT and CCTA has emerged as promising noninvasive imaging promising noninvasive imaging modality for coronary artery and modality for coronary artery and cardiac structural and functional cardiac structural and functional evaluation.evaluation.

• In order to gain high diagnostic In order to gain high diagnostic accuracy, the CT scanner system accuracy, the CT scanner system should provide high temporal and should provide high temporal and spatial resolutionsspatial resolutions

• Temporal resolution (TR):Temporal resolution (TR): • The duration of time for acquisation of The duration of time for acquisation of

a single frame of a dynamic process.a single frame of a dynamic process.

• TR=TR=TimeTime to repetition . to repetition .

• Temporal resolution in the region of Temporal resolution in the region of 100 ms is required to create relatively 100 ms is required to create relatively motionless images of the beating motionless images of the beating heartheart

•Spatial resolution (SR):The ability to distinguish two points

as separate in space .

The higher the spatial resolution ,the smaller the distance which can be distinguished

Historical backgroundHistorical background

CT was first introduced by Sir Godfrey Hounsfield in the 1970 & 1st commercial scanner at 1972.

Sir Godfrey N. Hounsfield, the father of computed tomography.

4.5 min/image 1972 2.5 min/image 1972

18s/image 1976 2s/image 1978

In the early 1980s, an important advance moved CT into the top of cardiac imaging. This was the introduction of the electron beam technology concept by Dr. Douglas Boyd .Arch Intern Med 2001;161:833–838.

• This technology decreased scan times to 50–100 ms, which essentially froze cardiac motion and thus dramatically changed our ability to image the beating heart. For the first time it was possible to view cardiac contractions and to visualize small structures such as calcium deposits within the walls of the coronary artery.

• An additional major advance in CT imaging came in the early 1990s with the introduction of helical/spiral CT imaging and its slip-ring technology

• With these advances, the X-ray beam was able to continuously rotate around the patient as the patient moved through the scanner gantry. These innovations decreased scan times to approx 500–1000 ms and ultimately produced data sets with spatial resolutions as small as 0.5 mm.

Radiology 2013;226:145–152.

• Dual Source Multi Slice CT 1991-1992. (sensitivity: 86% - specificity: 81%).• 8 slice scanners Dual Source CT 2000.

(sensitivity: 86% - specificity : 81%).

• 16 slice scanners Dual Source CT 2002.

(sensitivity: 96% - specificity : 83%).

• 64 slice scanners Dual Source CT 2004- 2005.

(sensitivity: 97% - specificity : 92-99%).• 256-320 slice scanners Dual Source CT 2007.

Dual Source CT (DSCT)Dual Source CT (DSCT)• Two X ray tubes Two X ray tubes

positioned at right positioned at right angleangle

• Two detector arrays Two detector arrays opposite to X ray tubesopposite to X ray tubes

• Temporal resolutions of Temporal resolutions of 100 ms is possible by 100 ms is possible by combining data from combining data from one-fourth of data one-fourth of data acquired by two acquired by two detectorsdetectors *Siemens ‘Definition’ at Johns Hopkins, 2006

Tube A

Tube B

Indications

Indications: A.Exclusion of CAD in patients at low to in patients at low to

intermediate pretest probability of intermediate pretest probability of CAD & detection of CAD when CAD & detection of CAD when inconclusive stress test inconclusive stress test or persistent or persistent symptoms despite – ve stress testsymptoms despite – ve stress test. . Likelihood (in %) of CAD according to sex, age, and symptomsLikelihood (in %) of CAD according to sex, age, and symptoms

WomenWomen MenMenAge Age

(years)(years)NonanginNonanginalalchest chest painpain

Atypical Atypical anginaangina

TypicaTypical l anginanginaa

Age Age (years(years

))

NonanginNonanginalalchest chest painpain

Atypical Atypical anginaangina

Typical Typical anginaangina

3030––3939 0.80.8 44 2626 3030––3939 55 2222 707040–4940–49 33 1313 5555 40–4940–49 1414 4646 909050–5950–59 88 3232 7979 50–5950–59 2222 5959 929260–6960–69 1919 5454 9191 60–6960–69 2828 6767 9494High: 90% pretest probability; intermediate: between 10% and 90% High: 90% pretest probability; intermediate: between 10% and 90% pretest probability; low: between 5% and 10% pretest probability; and pretest probability; low: between 5% and 10% pretest probability; and very low: 5% pretest probability.very low: 5% pretest probability.

B.B. Suspicion of coronary artery Suspicion of coronary artery anomalies.anomalies. MDCT has very high sensitivity and MDCT has very high sensitivity and specificity for coronary anomaliesspecificity for coronary anomalies..

C.C. Assessment of anatomy in complex Assessment of anatomy in complex congenital heart diseasecongenital heart disease..

D. Assessment of CABG. D. Assessment of CABG.

E. E. Assessment of Coronary Artery Assessment of Coronary Artery Stents?Stents? Material/Design/size Material/Design/size dependent dependent

`F. Evaluation of aortic disease. MDCT is the test of choice for evaluating aortic aneurysm and suspected aortic dissection.

Maximal intensity projection of the abdominal aorta,Maximal intensity projection of the abdominal aorta, demonstrating severe calcifications at the iliac bifurcationdemonstrating severe calcifications at the iliac bifurcation

G. Evaluation of PADG. Evaluation of PAD..

H. Evaluation of suspected pulmonary H. Evaluation of suspected pulmonary embolismembolism

I. Pulmonary vein evaluationI. Pulmonary vein evaluation can be can be performed, often before or after pulmonary performed, often before or after pulmonary vein isolation for atrial fibrillation.vein isolation for atrial fibrillation.

Fusion of MDCT and Electroanatomical Fusion of MDCT and Electroanatomical MappingMapping

K. Preoperative Coronary Preoperative Coronary AssessmentAssessment Prior to non coronary Cardiac Surgery

L. Complimentary to coronary cath.L. Complimentary to coronary cath.

M. Evaluation of chest pain M. Evaluation of chest pain (Triple (Triple rule out)rule out)

3-D volume rendered image demonstrating visualization of 3-D volume rendered image demonstrating visualization of the coronary venous system including the coronary sinus the coronary venous system including the coronary sinus ((double white arrow), a middle cardiac vein (black arrow), double white arrow), a middle cardiac vein (black arrow), and and a posterolateral vein (a posterolateral vein (single white arrow).single white arrow).

J. Coronary vein mapping Coronary vein mapping prior to placement of CRT

K. Triple rule outK. Triple rule out

N. New-Onset or Newly Diagnosed Clinical HF N. New-Onset or Newly Diagnosed Clinical HF and No Prior CAD.and No Prior CAD.

O.O. Evaluation of cardiac masses &Evaluation of cardiac masses & pericardial pericardial diseasedisease when other modalities such as TTE, when other modalities such as TTE, TEE, or MRI are unrevealing.TEE, or MRI are unrevealing.

P. Evaluation of Cardiac Structure & Function P. Evaluation of Cardiac Structure & Function (Inadequate images from other noninvasive (Inadequate images from other noninvasive methods). methods).

Q. Assessment of TAVI.Assessment of TAVI.

Contraindications:•Absolute contraindications :

A. Renal insufficiency. Given the potential for contrast nephropathy, patients with significant renal insufficiency (i.e., Cr > 1.5 mg/dL) should not undergo contrast-enhanced CT unless the information from the scan is critical and the risks/benefits are discussed with the patient.B. Known history of anaphylactic contrast reactionsC. PregnancyD. Clinical instability

•Relative contraindications

A. Contrast (iodine) allergy. Patients with allergic reactions to contrast should be pretreated with diphenhydramine and steroids before contrast administration.

B. Recent intravenous iodinated contrast administration. Patients who have received an IV dose of iodinated contrast should avoid contrast-enhanced CT scanning for 24 hours to reduce the risk of contrast nephropathy.

C. Hyperthyroidism. Iodinated contrast is contraindicated in the setting of uncontrolled hyperthyroidism due to possible precipitation of thyrotoxicosis.

D. Atrial fibrillation or any irregular heart rhythm, is a contraindication to coronary CT angiography due to image degradation from suboptimal ECG gating.

E. Inability to breath hold for at least 10 seconds. Image quality will be significantly reduced due to respiratory motion artifact if the patient cannot comply with breath hold instructions.

F. Morbid obesity.

G. Severe coronary calcium .

H. Metallic interference (e,g: pacemaker, defibrillator wires)

CCT LimitationsCCT Limitations

• LimitationsLimitations

• Rapid (>80 bpm) and irregular HRRapid (>80 bpm) and irregular HR• High calcium scores (>800-1000)High calcium scores (>800-1000)• StentsStents• Contrast requirements (Cr > 1.5 Contrast requirements (Cr > 1.5

mg/dl)mg/dl)• Small vessels (<1.5 mm) and Small vessels (<1.5 mm) and

collateralscollaterals• Obese and uncooperative patientsObese and uncooperative patients• RADIATION EXPOSURERADIATION EXPOSURE

Heart Rate

5050 7777 8585

Impact of Breathing

Impact of Breathing