- What is a triple rule-out CT scan?
-Coronary artery stenosis >50%
-Aortic dissection
-Pulmonary embolism - Triple Rule Out: Technical Challenge vs a Coronary CTA
-Larger volume of anatomy to scan
-Longer patient breath hold
-Increased radiation dose to patient
-Timing of study to two vascular beds that typically have peak enhancement 10-12 seconds apart
-Larger volume of anatomy to analyze - Triple Rule Out Protocols:
-You need to perform 2 or 3 quality exams in one CT acquisition
-Coronary CTA
-Aortic Evaluation for Dissection or Aneurysm
-Pulmonary arteriogram - Triple Rule Out Challenges/Solutions
-Optimal opacification of both the pulmonary artery and the aortic circulations must be optimally opacified
-Although both peaks occur in close proximity the pulmonary arteries opacify well 10-12 seconds before the aorta
-To maintain optimal opacification you can increase contrast volume (130 cc) or decrease injection rates to lengthen the transit opacification time (4 cc vs 5-6cc/sec) - Triple Rule Out: Challenges/Solutions
-Fast Flash acquisition with high pitch values (3.2 or greater) is ideal to minimize contrast volume used by decreasing scan times to 1-2 seconds
-Split bolus common with second bolus usually having lower injection rates (5 cc vs 3 cc) and volumes (80-100 cc vs 20-30 cc). Split injection with second bolus of 70%-30% (contrast/saline) for longer injection volumes and increased volume injection times - Rational and Objectives
-To compare the image quality of dedicated coronary computed tomography angiography (cCTA) to that of triple rule-out (TRO) CTA designed to evaluate the coronary arteries, thoracic aorta, and pulmonary arteries.
Conclusions
-A TRO-CTA protocol using 95 mL of contrast can provide comparable coronary image quality and coronary vascular enhancement as compared to dedicated cCTA with 70 mL of contrast.
Comparison of Image Quality and Arterial Enhancement with a Dedicated Coronary CTA Protocol versus a Triple Rule-Out Coronary CTA Protocol
Halpern EJ et al. - "Consecutive cCTA examinations performed by a single radiologist over 1 year were reviewed. Biphasic injection protocols were employed: 70 mL of optiray-350 followed by 40 mL of saline injected at 5.5 mL/second for dedicated cCTA; 70 mL of optiray-350 followed by 25 mL of the contrast diluted with 25 mL of saline injected at 5.0 mL/second for TRO-CTA. Two independent cardiovascular radiologists reviewed the coronary vessels in each case and rated diagnostic image quality on a 5 point scale (1, suboptimal; 3, adequate; 5, excellent). Vascular enhancement was measured in the coronary arteries, aorta, and pulmonary arteries."
Comparison of Image Quality and Arterial Enhancement with a Dedicated Coronary CTA Protocol versus a Triple Rule-Out Coronary CTA Protocol
Halpern EJ et al.
Acad Radiol 2009 Sep;16(9):1039-1048 - "There was excellent interobserver agreement between the cardiovascular radiologists (kappa = 0.91). Coronary image quality score were similar among 260 dedicated cCTA studies and 168 TRO-CTA studies (mean: 3.8-3.9. P > .18). At least one coronary segment demonstrated suboptimal image quality in 8% of examinations, including 18 dedicated cCTA studies and 16 TRO studies (P = .94). Enhancement was greater in the distal thoracic aorta of TRO patients (336 vs. 311 Hounsfield units; P = .01); no other significant differences in enhancement were identified in the aorta and coronary arteries of dedicated cCTA and TRO studies. Vascular enhancement was adequate for diagnostic evaluation of the pulmonary arteries in all TRO studies."
Comparison of Image Quality and Arterial Enhancement with a Dedicated Coronary CTA Protocol versus a Triple Rule-Out Coronary CTA Protocol
Halpern EJ et al.
Acad Radiol 2009 Sep;16(9):1039-1048 - Triple Rule Out Protocol
- Scan is from above arch (1-2 cm) thru the base of the heart
- CT angiography begins 5 seconds after contrast reaches the left atrium (64 MDCT)
- Injection is biphasic with 70 ml of iodine 350 followed by 50 ml of diluted contrast (25 ml of iodine 350 and 25 ml saline)
- Beta blockers critical
Triple-Rule-Out CT Angiography for Evaluation of Acute Chest Pain and Possible Acute Coronary Syndrome
Halpern EJ
Radiology 2009; 252:332-345 - “ In ED patients with atypical chest pain and low to intermediate risk, the triple rule-out protocol may be preferred, especially in older patients who have relatively lower risk of lifelong radiation-induced cancer. However, the increased radiation dose resulting from the extended volume coverage with this protocol should be fully considered prior to performing this protocol. Therefore, in ED patients who have a low clinical suspicion of pulmonary embolism and acute aortic syndrome, especially younger patients, dedicated coronary CT angiography accompanied by modifications to reduce radiation dose is recommended.”
Coronary CT angiography in emergency department patients with acute chest pain: triple rule-out protocol versus dedicated coronary CT angiography
Lee Hy, Yoo SM, White CS
Int J Cardiovasc Imaging 2009 Mar;25(3):319-26 - “ In ED patients with atypical chest pain and low to intermediate risk, the triple rule-out protocol may be preferred, especially in older patients who have relatively lower risk of lifelong radiation-induced cancer. However, the increased radiation dose resulting from the extended volume coverage with this protocol should be fully considered prior to performing this protocol.”
Coronary CT angiography in emergency department patients with acute chest pain: triple rule-out protocol versus dedicated coronary CT angiography
Lee Hy, Yoo SM, White CS
Int J Cardiovasc Imaging 2009 Mar;25(3):319-26 - “ Therefore, in ED patients who have a low clinical suspicion of pulmonary embolism and acute aortic syndrome, especially younger patients, dedicated coronary CT angiography accompanied by modifications to reduce radiation dose is recommended.”
Coronary CT angiography in emergency department patients with acute chest pain: triple rule-out protocol versus dedicated coronary CT angiography
Lee Hy, Yoo SM, White CS
Int J Cardiovasc Imaging 2009 Mar;25(3):319-26 - "The image quality of triple rule out CTA is comparable to that of dedicated coronary CTA, showing no statistically significant difference in motion artifacts or opacification, and therefore may be alternative and useful diagnostic study in a select group of emergency patients."
Triple Rule-out and Dedicated Coronary Artery CTA: Comparison of Coronary Image Quality
Rahmani N, Jeudy J, White CS
Acad Radiol 2009; 16:604-609 - Triple Rule Out Protocol
- 64 MDCT Scanner
- Cephalic to caudal direction scanning
- 130 cc of contrast injected over 66 seconds (80 cc at 5 cc/sec, 50 cc at 2 cc/sec, then 50 cc saline at 2 cc/sec)
Triple Rule-out and Dedicated Coronary Artery CTA: Comparison of Coronary Image Quality
Rahmani N, Jeudy J, White CS
Acad Radiol 2009; 16:604-609 - "Triple rule-out CT is feasible in patients with suspicion of PE, reveals a wide range of vascular and non-vascular chest disease, and offers an excellent overall diagnostic performance."
Triple Rule-Out CT in Patients with Suspicion of Acute Pulmonary Embolism: Findings and Accuracy
Schertler T et al.
Acad Radiol 2009; 16:708-717 - Triple Rule Out Protocol
Dual Source CT Scanner
- 110 ml of contrast injected at 4 cc/sec followed by 30 ml of saline
- Trigger set in ascending aorta
- Scanning was done in a cranial caudal direction
Triple Rule-Out CT in Patients with Suspicion of Acute Pulmonary Embolism: Findings and Accuracy
Schertler T et al.
Acad Radiol 2009; 16:708-717 - "Triple rule out” protocols designed to simultaneously assess the aorta, pulmonary arteries and coronary arteries are a compromise between dedicated protocols for each diagnosis. The diagnostic value and appropriate clinical use of these protocols remain to be shown by randomized, controlled, outcomes based trials."
Role of computed tomography in the evaluation of acute chest pain
Urbania TH et al.
J Cardiovasc Comput Tomogr (2009) 3. Supplement 1, S13-S22 - “ The focus of this article is to review the current literature of the uses of Coronary CTA and “triple rule out” protocols in the emergency department setting and to provide a chest pain algorithm, showing how Coronary CTA can be implemented effectively in clinical focus.”
Cardiac CT in the emergency department: Convincing evidence, but cautious implementation
Cury RC et al
J Nucl Cardiol 2011;18:331-341 - “ A triple rule out protocol (TRO) may be considered if an additional suspicion of pulmonary embolism or acute aortic disease is present, when using 64-slices or more.”
Cardiac CT in the emergency department: Convincing evidence, but cautious implementation
Cury RC et al
J Nucl Cardiol 2011;18:331-341 - “MDCT is used for the detection of 3 of the most common life-threatening causes of chest pain-coronary artery disease, acute aortic syndrome, and pulmonary emboli. While triple rule-out protocol can be very useful and potentially cost effective when used appropriately, concern has risen regarding the overuse of this technology, which could expose patients to unnecessary radiation and iodinated contrast.”
Evaluation of Acute Chest Pain in the Emergency Department: “Triple Rule-Out” Computed Tomography Angiography
Yoon ES, Wann S
Cardiol Rev 2011 May-Jun;19(3):115-21 - “ The triple rule-out protocol is most appropriate for patients who present with acute chest pain, but are judged to have low to intermediate increased risk for acute coronary syndrome, and whose chest pain symptoms might also be attributed to acute pathologic conditions of the aorta or pulmonary arteries. MDCT should not be used as a routine screening procedure.”
Evaluation of Acute Chest Pain in the Emergency Department: “Triple Rule-Out” Computed Tomography Angiography
Yoon ES, Wann S
Cardiol Rev 2011 May-Jun;19(3):115-21 - “Continued technical improvements in acquisition speed and spatial resolution of computed tomography images, and development of more efficient image reconstruction algorithms which reduce patient exposure to radiation and contrast, may result in increased popularity of MDCT for "triple rule-out”.
Evaluation of Acute Chest Pain in the Emergency Department: “Triple Rule-Out” Computed Tomography Angiography
Yoon ES, Wann S
Cardiol Rev 2011 May-Jun;19(3):115-21 - “ Among patients with acute chest pain, a triple rule-out approach resulted in higher radiation exposure compared with cardiac CT, but was not associated with improved diagnostic yield, reduced clinical events, or diminished downstream resource use.”
Comparative diagnostic yield and 3 month outcomes of “triple rule-out” and standard protocol coronary CT angiography in the evaluation of acute chest pain
Madder RD et al.
J Cardiovascular Comput Tomogr (2011)5, 165-171 - “ Among 2068 patients (272 triple rule-out and 1796 cardiac CT angiograms) the composite diagnostic yield was 14.3% with triple rule-out and 16.3% with cardiac CT and was driven by the diagnosis of obstructive pulmonary disease.”
Comparative diagnostic yield and 3 month outcomes of “triple rule-out” and standard protocol coronary CT angiography in the evaluation of acute chest pain
Madder RD et al.
J Cardiovascular Comput Tomogr (2011)5, 165-171 - “ Compared with cardiac CT, the triple rule out approach was associated with higher radiation dose (12.0±5.6 mSv versus 8.2±4.0 mSv), a greater incidence of subsequent emergency center evaluations, and more downstream pulmonary embolism protocol CT angiography.”
Comparative diagnostic yield and 3 month outcomes of “triple rule-out” and standard protocol coronary CT angiography in the evaluation of acute chest pain
Madder RD et al.
J Cardiovascular Comput Tomogr (2011)5, 165-171 - “We conducted a randomized diagnostic trial to compare the efficiency of a comprehensive cardiothoracic CT examination in the evaluation of patients presenting to the emergency department with undifferentiated acute chest discomfort or dyspnea. We randomized the emergency department patients clinically scheduled to undergo a dedicated CT protocol to assess coronary artery disease, pulmonary embolism, or aortic dissection to either the planned dedicated CT protocol or a comprehensive cardiothoracic CT protocol..”
Usefulness of comprehensive cardiothoracic computed tomography in the evaluation of acute undifferentiated chest discomfort in the emergency department (CAPTURE)
Rogers IS et al.
Am J Cardiol 2011 March 1;107(5):643-650 - “Comprehensive cardiothoracic CT scanning was feasible, with a similar diagnostic yield to dedicated protocols. However, it did not reduce the length of stay, rate of subsequent testing, or costs. In conclusion, although this "triple rule out" protocol might be helpful in the evaluation of select patients, these findings suggest that it should not be used routinely with the expectation that it will improve efficiency or reduce resource use.”
Usefulness of comprehensive cardiothoracic computed tomography in the evaluation of acute undifferentiated chest discomfort in the emergency department (CAPTURE)
Rogers IS et al.
Am J Cardiol 2011 March 1;107(5):643-650 - Is there a consensus then in the literature?
-Triple rule out can be done successfully with a modification of CT scan protocols
-Triple rule out can be used successfully in a select patient population where the differential dx for acute chest pain is non-specific
-Radiation dose is a consideration so potentially best in older patients where dose is less of an issue
-Triple rule out should not replace clinical judgment in the ER patient
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