Transcript Document

Practice guidelines in
MS-CT coronarography
Ladislav Pavic, MD, PhD
Sunce Clinics Zagreb / Sarajevo
Croatia / Bosnia & Herzegovina
Preconditions for adequate imaging work-up
Adequate indication
Adequate imaging technique / procedure
Adequate interpretation & reporting
Indications for coronary CTA:
1. Detection of CAD with prior test results: Evaluation of chest pain syndrome
Uninterpretable or equivocal stress test result (exercise, perfusion, or stress echo)
2. Detection of CAD: Evaluation of chest pain syndrome
Intermediate pre-test probability of CAD, ECG uninterpretable or unable to exercise
3. Detection of CAD: Acute chest pain
Intermediate pre-test probability of CAD, no ECG changes and serial enzymes negative
“Triple rule out” exclude obstructive CAD, aortic dissection, and pulmonary embolism
4. Evaluation of coronary arteries in patients with new onset heart failure to assess
etiology
5. Detection of CAD: Symptomatic
Evaluation of suspected coronary anomalies
ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR 2006 appropriateness criteria for cardiac computed tomography
and cardiac magnetic resonance imaging: a report of the American College of Cardiology Foundation Quality Strategic
Directions Committee Appropriateness Criteria Working Group, American College of Radiology, Society of Cardiovascular
Computed Tomography, Society for Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology, North
American Society for Cardiac Imaging, Society for Cardiovascular Angiography and Interventions, and Society of
Interventional Radiology.
Hendel RC, et al. J Am Coll Cardiol. 2006;48:1475-1497.
Uncertain indication for coronary CTA:
6. Detection of CAD: Asymptomatic (without chest pain syndrome)
High coronary heart disease (CAD) risk (Framingham)
7. Detection of CAD: Post-revascularization (PCI or CABG)
Evaluation of bypass graft and coronary anatomy
History of percutaneous revascularization with stents
8. Risk assessment: General population-asymptomatic (calcium scoring)
Moderate CHD risk (Framingham)
High CHD risk (Framingham)
ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR 2006 appropriateness criteria for cardiac computed tomography
and cardiac magnetic resonance imaging: a report of the American College of Cardiology Foundation Quality Strategic
Directions Committee Appropriateness Criteria Working Group, American College of Radiology, Society of Cardiovascular
Computed Tomography, Society for Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology, North
American Society for Cardiac Imaging, Society for Cardiovascular Angiography and Interventions, and Society of
Interventional Radiology.
Hendel RC, et al. J Am Coll Cardiol. 2006;48:1475-1497.
CCTA imaging technique
Ideal:
…to keep patient doses as low as reasonably achievable
but consistent with obtaining the desired medical information!
Gerber TC, et al. Ionizing radiation in cardiac imaging: a science advisory from the American Heart
Association Committee on Cardiac Imaging of the Council on Clinical Cardiology and Committee on
Cardiovascular Imaging and Intervention of the Council on Cardiovascular Radiology and Intervention.
Circulation. 2009 Feb 24;119(7):1056-65. Epub 2009 Feb 2.
CCTA is particularly amenable to radiation dose reduction
using hardware and acquisition protocols customized to patients’ characteristics.
Minimal hardware requirement: 64 ≥ slice cardiac CT-scanner
CCTA imaging technique
A radiation consulting team was selected by the Consortium Executive
Committee...
This team created a Best-Practice Model for Scan Acquisition designed
to reduce radiation dose.
CCTA imaging technique
Best-Practice Model for Scan Acquisition
Instructions to the patient and ordering physicians:
At the time of scheduling,
the patient should be instructed to avoid solid food or caffeine within 6 hours of
the scan,
but to take oral fluids liberally to avoid dehydration, and to continue taking βblocking drugs;
these measures encourage heart rate stability
Medical history:
If the patient has taken β-blockers prior to arrival, subsequent doses should be
adjusted
Nursing assessment:
Vital signs including heart rate, heart rate variability, and blood pressure
are assessed and monitored during the premedication period
CCTA imaging technique
Best-Practice Model for Scan Acquisition
Administration of β-blockers:
For most current retrospective, gated-acquisition protocols,
including dual-source scanners,
heart rate control reduces radiation dose
by allowing a more narrow acquisition window
For patients with baseline heart rates greater than 65/min, systolic blood pressure
greater than 90 mm Hg, and body mass index greater than 18:
administer 100 mg of oral metoprolol or comparable dose equivalent 30
minutes to 1 hour prior to the procedure,
or comparable intravenous doses with telemetric monitoring
For patients with baseline heart rates greater than 50/min but less than 65/min and
blood pressure greater than 90 mm Hg,
administer 50 mg of oral metoprolol to block heart rate acceleration during scan
Nitroglycerin administration:
If blood pressure is greater than 90 mm Hg, nitroglycerin generally improves image
quality, yielding a lower frequency of repeat scans
CCTA imaging technique
Best-Practice Model for Scan Acquisition
Protocol parameters:
Because radiation dose is directly proportional to z axis scan length,
the field of view should be consistently restricted
from mid-pulmonary artery to the diaphragm;
extended field of view triple rule-out scans should be limited
to patients with clinical likelihood of either a pulmonary embolus
or aortic dissection
A simple rule is used to reduce scan voltage from the standard 120 kVp;
100 kVp may be substituted in patients with a body weight of 85 (90) kg or less
and a body mass index of less than 30 (32),
subject to physician discretion
Tube current modulation by electrocardiographic pulsing should be used
in all patients unless atrial fibrillation or frequent premature contractions are
present
CCTA imaging technique
Best-Practice Model for Scan Acquisition
Acquisition window:
For scanners with adjustable acquisition windows during electrocardiographic pulsing,
the following adjustments are recommended:
Heart rate lower than 65/min: 65% to 75%
Heart rate of 66/min to 70/min: 60% to 80%
Heart rate greater than 70/min: 35% to 80%
Highly variable heart rates or atrial fibrillation
may preclude the use of electrocardiographic dose modulation,
but this should be weighed against the patient's age and the suitability of other
diagnostic options
If scanner model allows tube current adjustment,
the lowest available tube current outside the acquisition window should be
used (eg, 5% of maximal);
this is equally applicable in obese patients because the data during systole will
not be used
It was agreed that Ca-scoring should be done only if specifically ordered!
CCTA imaging technique
Advanced Cardiovascular Imaging Consortium (ACIC) - Results
CCTA imaging technique
Our experience
Sunce, Zagreb
Siemens 64
Dual-Source
(n = 100)
PROTECTION I*
Siemens 64
Dual-Source
(n = 100)
31,2
26.3 (24.1-28.7)
0
350 (67.2 %)
62 (54-65)
64 (56-72)
40
70 (13.4)
60
451 (86.6)
125 (113-142)
133 (121-146)
CTDIvol, mGy
45,9
47.8 (35.8-60.8)
Dose-length product, mGy X cm
721,9
798 (580-1007)
10
11 (8-14)
Characteristics
Body mass index
Without β-blockers
Heart rate, beats/min
Tube voltage, kV
100
≥120
Scan length, mm
Effective dose estimate, mSv
*International PRospective Multicenter Study On RadiaTion Dose Estimates Of Cardiac CT AngIOgraphy IN Daily Practice (PROTECTION I)
Hausleiter J, et al. Estimated radiation dose associated with cardiac CT angiography. JAMA. 2009 Feb 4;301(5):500-7.
CCTA, adequate interpretation & reporting
Society of Cardiovascular Computed Tomography (SCCT)
Underlying principles of interpreting
Raff GL, et al SCCT guidelines for the interpretation and reporting
of coronary computed tomographic angiography. J Cardiovasc
Comput Tomogr. 2009 Mar-Apr;3(2):122-36. Epub 2009 Jan 29.
CCTA, adequate interpretation & reporting
Society of Cardiovascular Computed Tomography (SCCT)
Stenosis Grading
Raff GL, et al SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography. J Cardiovasc Comput
Tomogr. 2009 Mar-Apr;3(2):122-36. Epub 2009 Jan 29.
CCTA, adequate interpretation & reporting
Society of Cardiovascular Computed Tomography (SCCT)
Structured reporting
Raff GL, et al SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography. J Cardiovasc Comput
Tomogr. 2009 Mar-Apr;3(2):122-36. Epub 2009 Jan 29.
CCTA, adequate interpretation & reporting
Society of Cardiovascular Computed Tomography (SCCT)
Structured reporting
Raff GL, et al SCCT guidelines for the interpretation and reporting of coronary computed tomographic angiography. J Cardiovasc Comput
Tomogr. 2009 Mar-Apr;3(2):122-36. Epub 2009 Jan 29.
CCTA, adequate interpretation & reporting
Images, example
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