BJR http://dx.doi.org/10.1259/bjr.

20150705
© 2016 The Authors. Published by the British Institute of Radiology under the terms
Received: Revised: Accepted: of the Creative Commons Attribution-NonCommercial 4.0 Unported License
22 August 2015 17 February 2016 23 February 2016 http://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted
non-commercial reuse, provided the original author and source are credited.

Cite this article as:

Vardhanabhuti V, Nicol E, Morgan-Hughes G, Roobottom CA, Roditi G, Hamilton MCK, et al. Recommendations for accurate CT diagnosis of
suspected acute aortic syndrome (AAS)—on behalf of the British Society of Cardiovascular Imaging (BSCI)/British Society of Cardiovascular
CT (BSCCT). Br J Radiol 2016; 89: 20150705.

GUIDELINES & RECOMMENDATIONS

Recommendations for accurate CT diagnosis of suspected
acute aortic syndrome (AAS)—on behalf of the British
Society of Cardiovascular Imaging (BSCI)/British Society
of Cardiovascular CT (BSCCT)
1,2
VARUT VARDHANABHUTI, FRCR, 3EDWARD NICOL, FRCP, 4GARETH MORGAN-HUGHES, FRCR, 1,5CARL A ROOBOTTOM, FRCR,
6
GILES RODITI, FRCR, FRCP, 7MARK C K HAMILTON, FRCR, 8RUSSELL K BULL, FRCR, 9FRANCHESCA PUGLIESE, FRCR,
10
MICHELLE C WILLIAMS, MRCP, 3JAMES STIRRUP, MRCP, 3SIMON PADLEY, FRCR, 11ANDREW TAYLOR, FRCR,
9
L CERI DAVIES, FRCR, 12ROGER BURY, FRCR and 13STEPHEN HARDEN, FRCR
1
Plymouth University Peninsula Schools of Medicine and Dentistry, John Bull Building, Plymouth, UK
2
Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
3
Radiology Department, Royal Brompton Hospital, London, UK
4
Department of Cardiology, Derriford Hospital, Plymouth, UK
5
Department of Radiology, Derriford Hospital, Plymouth, UK
6
Department of Radiology, Glasgow Royal Infirmary, Glasgow, UK
7
Department of Radiology, Bristol Royal Infirmary, Bristol, UK
8
Department of Radiology, Royal Bournemouth Hospital, Bournemouth, UK
9
Centre for Advanced Cardiovascular Imaging, NIHR Cardiovascular Biomedical Research Unit, Barts and The London School of Medicine &
Barts Health NHS Trust, London, UK
10
University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Royal Infirmary of Edinburgh, Edinburgh, UK
11
Cardiothoracic Unit, Great Ormond Street Hospital for Children, London, UK
12
Radiology Department, Blackpool Teaching Hospitals, Blackpool, UK
13
Department of Cardiothoracic Radiology, University Hospital Southampton NHS Trust, Southampton, UK

Address correspondence to: Dr Varut Vardhanabhuti

E-mail: vvar@me.com

ABSTRACT
Accurate and timely assessment of suspected acute aortic syndrome is crucial in this life-threatening condition. Imaging
with CT plays a central role in the diagnosis to allow expedited management. Diagnosis can be made using locally
available expertise with optimized scanning parameters, making full use of recent advances in CT technology. Each
imaging centre must optimize their protocols to allow accurate diagnosis, to optimize radiation dose and in particular to
reduce the risk of false-positive diagnosis that may simulate disease. This document outlines the principles for the
acquisition of motion-free imaging of the aorta in this context.

INTRODUCTION dissection as follows: Type A, involving the ascending aorta;

Timely and accurate assessment of suspected acute aortic Type B, limited to aorta portion distal to left subclavian
syndrome (AAS) is vital in this potentially life-threatening artery; and Type B with aortic arch involvement, in-
condition with significant pre-hospital and in-hospital volving the arch (between the innominate and left sub-
mortality rates of up to 20% and 30%, respectively.1 There clavian arteries) but not involving the ascending aorta.10
are many definitions of AAS; however, for the purpose of The classification reflects the current management ap-
this document, AAS is defined as aortic dissection, intra- proach, which supports that Type B dissection can be
mural haematoma and the complications arising from managed conservatively. With recent advances in CT
penetrating atherosclerotic aortic ulcer.2–4 These are not scanning technology and increasing expertise in car-
mutually exclusive and may represent variations on the diovascular CT, the purpose of these recommendations
same disease spectrum.4–7 Different classifications of aortic are to outline the best practice for the investigation of
dissection exist,8,9 but to avoid confusion, we recommend suspected AAS so that unequivocal diagnosis can be
using the most recently proposed classification of defining made based on imaging. Specifically, accurate motion-
 BJR Vardhanabhuti et al

Figure 1. Risk stratification for acute aortic syndrome and appropriate management strategy.

free imaging is vital to eliminate the possibility of false-positive patients with low clinical risk, an alternative diagnosis should
diagnoses, needless patient transfer and potentially disastrous be considered but definitive imaging may also be required.
unnecessary surgery, all of which have been reported.11–16
Patients with high-risk conditions such as those with increased
Assessment of pre-test likelihood wall stress (e.g. hypertension, phaeochromocytoma, cocaine use)
Recommendation 1 and aortic medial abnormalities (e.g. Marfan, Loeys–Dietz, Ehlers–
Danlos, Turner syndromes, inflammatory vasculitides) have in-
Assessment of pre-test clinical probability of AAS should be creased risks of developing thoracic aortic aneurysm and
performed using American College of Cardiology Founda- dissection.18–23 High-risk clinical features and examinations
tion (ACCF)/American Heart Association (AHA) guidance.17 should also be borne in mind, allowing for appropriate patient
selection for imaging. Pre-test likelihood assessment should
Initial evaluation of AAS should be based upon careful history and be performed to exclude other causes and select appropriate
clinical examination (i.e. assessing for peripheral pulse deficits and patients for timely imaging.
potential end organ damage secondary to dissection) resulting in
the ability to determine a pre-test likelihood of AAS. A summary Imaging modality and technique
of pre-test likelihood is shown in Figure 1 which categorizes Recommendation 3
patients into low, intermediate or high likelihood of AAS.17
When imaging is deemed appropriate, CT scan is the
Recommendation 2 imaging modality of choice in acute scenario.

Patients deemed to have intermediate or high risk should Transthoracic echocardiography Transthoracic echocardiog-
proceed to have imaging to establish a definitive diagnosis. In raphy usually allows adequate assessment of the aorta and can

2 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 Guidelines & recommendations: Recommendations for accurate CT diagnosis of AAS by BSCI/BSCCT BJR

often diagnose involvement of the aortic root and proximal Figure 2. Ungated CT angiogram of the aorta demonstrating
ascending aorta. However, other segments (e.g. the aortic arch, pulsation artefact (arrows).
proximal descending aorta and abdominal aorta) are sometimes
difficult to see owing to inadequate acoustic window. The value
of transthoracic echocardiography is further limited in non-standard
patients (e.g. abnormal chest wall configuration, obesity, pre-existing
pulmonary emphysema, or patients on mechanical ventilation).

Transoesophageal echocardiography The proximity of the

oesophagus to the aorta allows high-quality images of the aorta
to be obtained. The high accuracy of transoesophageal echo-
cardiography for the diagnosis of aortic dissection has been
reported previously.24,25 The largest series examining ascending
aortic dissection shows a sensitivity and specificity of 96.8% and
100%, respectively.26 The main drawbacks of transoesophageal
echocardiography are sedation requirement and access to ap-
propriate expertise.

CT The accuracy of CT in the diagnosis of aortic dissection is

high with sensitivity and specificity ranging around 98–100%.
As per evidence based on the International Registry of Acute
Aortic Dissection registry27 and the Spanish Registry of Acute possible in order to reduce radiation dose. Retrospective gating
Aortic Syndromes,28 CT is already the preferred imaging mo- usually incurs a penalty of significantly higher radiation dose. A
dality and was used in 74% and 77% of patients in each registry, dose–length product (DLP) for retrospective thoracic CT an-
respectively. One of the major drawbacks of CT is the pulsation giogram can be as high as 2547 mGy cm21,38 although there
artefact which is addressed in this article. are specific instances where this may have to be performed (see
Specific protocol examples section). Broad detector array sys-
MRI MRI has very high sensitivity (97–100%) and specificity tems, e.g. 128 detector rows (e.g. Philips iCT; Philips, Andover,
(94–100%) for the diagnosis of aortic dissection.29,30 MRI is free MA), 256 detector rows (e.g. GE Revolution; General Electrics,
from ionizing radiation, but limitations are low availability and Milwaukee, WI) or 320 detector rows (e.g. Toshiba Aquilion
time taken for examination (even in experienced sites, imaging One; Toshiba, Irvine, CA) or dual-source systems, should be
time can be 20–30 min) means lack of suitability in acute setting. optimized to allow motion-free imaging which may not require
ECG synchronization if temporal resolution is rapid enough, but
Given the available evidence, CT is recommended as the imaging this depends upon scanner capabilities.
modality of choice in the acute scenario because of accuracy,
ease of access and relatively quick examination time.5,31 Once Recommendation 5
AAS is confirmed, in addition, echocardiography may be used to
assess complications such as aortic valve dysfunction, pericardial A non-contrast ECG synchronization CT scan should be
tamponade, or wall motion abnormalities, but this should not performed to look for a rim of hyper-attenuation around
delay definite surgical management. In equivocal cases of acute the aortic wall (Figure 3).
intramural haematoma, a characteristic ‘‘echo-free space or
echolucent area’’ within the thickened aortic wall that may be This should be performed prior to the contrast-enhanced study.
sought in supportive of diagnosis.31–34 MRI/MR angiogram is The use of a non-contrast scan may reduce the likelihood of
not recommended in acute scenario but is useful in the context false-negative diagnosis on contrast studies in cases of isolated
of follow-up of known aortic dissections, particularly in young subtle intramural haematoma. Incidences vary but range from
patients35 in line with the as low as reasonably practical principle 6% to 30%.17,39–41 In addition, a non-contrast scan may enable
of radiation dose optimization. the visualization of acute haemorrhagic content within the aortic
wall that can be associated with the other forms of AAS2 and
Recommendation 4 also localized rupture into the pericardium. Where possible,
a low-dose setting should be utilized. The non-contrast scan
All CT scans should be performed with the aim of producing does not need to encompass the whole aorta and can be limited
motion-free images of the aortic root, which is prone to to covering from aortic arch to diaphragmatic sulcus.
pulsation artefact (Figure 2).
Coverage
In systems with 64-detector-row arrays (or 80-detector-row Recommendation 6
arrays—these systems may be configured as 128 or 160 slices per
rotation systems depending upon technical details of reconstruc- Coverage should be limited to thorax from aortic arch to
tion), this should involve routine use of electrocardiogram (ECG) diaphragmatic sulcus in the first instance, unless the patient
synchronization.36,37 Prospective triggering should be used where is deemed high risk or has known disease.

3 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 BJR Vardhanabhuti et al

Figure 3. Non-contrast CT demonstrating typical appearance There are three distinct methods of scan initiation that may
of a hyperattenuating crescentic ring that can be seen in acute be used.
intramural haematoma (arrowheads). (a) Fixed delay: this must take into account the contrast injection
rate, contrast concentration, table feed speed, scanner detector
width and perceived patient cardiac output. This is effectively
a prediction and is not recommended.
(b) Test bolus: this technique will allow homogeneous contrast
enhancement and takes into account the patient’s haemody-
namic status. However, a disadvantage is that it requires
a small increase in the overall contrast medium dose for the
test bolus (usually #20 ml).44 Lower tube voltage protocols for
test bolus imaging can be used to reduce radiation further.45
(c) Bolus tracking: with a region of interest placed in the
ascending thoracic aorta, the scan is commenced once a pre-
determined threshold Hounsfield unit has been reached. It
should be noted that in AAS, there is a risk that if the region
of interest is incorrectly placed (e.g. as can occur in the false
lumen of a dissected aorta), inappropriate triggering may
occur. The operator should be aware that manual initiation
may be required in this instance.

The contrast injection should be given via the right arm to elim-
inate the streak artefacts that might be caused by injection from the
left side, obscuring assessment of head and neck vessels that may
Initial coverage should be as for a CT Thorax (covering aortic potentially be involved. The amount of contrast and rate of in-
arch to diaphragmatic sulcus). As the diagnostic rate for positive jection depends upon the speed of scan acquisition, tube voltage,
findings may be as low as 2.7%,42,43 coverage should be limited patient size and z-axis coverage, as well as the iodine concentration
in the first instance in patients with intermediate pre-test prob- used and whether a saline bolus chaser is used. The aim is to
ability in order to avoid unnecessary radiation dose. If the scan achieve adequate contrast concentration of at least 250 HU in the
proves positive, then a repeat scan can be performed with ex- aorta.46 The use of a saline flush is recommended as this produces
tended coverage to the common femoral arteries to allow for a higher contrast peak opacification for any given iodine flux and
endovascular access planning and to fully delineate the full extent makes most efficient use of administered contrast.47
of the dissection. In those patients deemed “high risk” for dis-
section following risk assessment, particularly with abdominal On the most recent generation of CT scanners, it is now feasible
and/or lower limb symptoms/signs, it is reasonable to perform to use low tube voltage for routine imaging of the aorta, even in
complete coverage of the entire aorta and to include the iliofe- large-sized patients (often in conjunction with iterative re-
moral arteries from the outset. In addition, in situations where construction techniques). Owing to the greater photon ab-
there is known aortic dissection, extended coverage is mandatory. sorption of iodinated contrast at energies nearer 70 kVp, this
results in greater relative vascular enhancement. This in turn
Premedication allows for smaller volumes of contrast to be used at lower flow
In the acute setting, we do not advocate the use of beta-blocker rates (iodine delivery rates of 1.3–1.5 g s21). Similarly, the use of
medication to slow the heart rate (HR). high-pitch dual-source systems need less iodine delivery rate but
owing to acquisition speed, adjustment of the acquisition delay
Patient size may be required.48 Biphasic or triphasic injections should be
Patient size or body mass index (BMI)-adjusted tube current/ considered to reduce contrast dose, produce a uniform en-
voltage should be employed for maximum dose optimization. As hancement pattern without affecting the maximal enhancement
a general rule, lower BMI will allow for the use of flow tube and also minimize artefacts from dense contrast material
voltage (kVp) and provided that tube current is also optimized, within the superior vena cava. Patient-specific protocols can
dose can be reduced. Lowering kVp will affect image contrast also be employed and may achieve more uniform contrast
and will allow for the use of less iodine intravenous contrast (see enhancement.49
Recommendation 8 section).
Recommendation 8
Scan initiation and contrast Regime
Recommendation 7 The key to adequate contrast opacification is to achieve an
iodine delivery rate of at least 1.6 g s21 (ideally up to 2 g s21)
A dedicated injection protocol should be used, taking into when using a tube voltage of 120 kVp.
account the speed of scan acquisition and coverage with the
aim to achieve adequate contrast concentration of at least The two factors to consider when calculating iodine flux are the
250 HU in the aorta. iodine concentration of the contrast media and the injection

4 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 Guidelines & recommendations: Recommendations for accurate CT diagnosis of AAS by BSCI/BSCCT BJR

rate, i.e. 300 mg of iodine per millilitre injected at 6.7 ml s21 vs Basic concept
contrast media of 400 mg of iodine per millilitre injected at For a 64-detector-row system (including “128-slice” scanners
5 ml s21. It is worth noting that patient factors also affect iodine and similar), prospective (“step-and-shoot”) acquisition should
delivery rate (i.e. cardiac output and weight). Therefore, it is be employed where possible with phase selection based on HR.
recommended that contrast volume should be determined based This is because the phase with minimal motion of the aortic root
on the patient’s weight, usually delivering at least 300-mg iodine varies with HR. At HR ,65 beats per minute (bpm), this is
per kilogram for examinations of the whole aorta with 64-detector usually the end-diastolic phase. With HR .65 bpm, this is
row systems. However, advanced broad detector array or usually end-systolic phase.55 Where phase selection is not ad-
dual-source systems may permit lower volumes in view of justable (e.g. on a scanner with prospective helical acquisition
their increased speed of acquisition.48 with diastolic phase acquisition only for slow HRs), then a ret-
rospective protocol may need to be employed for patients with
If using a 64-detector-row CT for the entirety of the aorta, faster HRs. Retrospectively gated acquisitions can be used but
a decrease in aortic enhancement in the descending aorta may be should be only employed where no prospectively triggering al-
observed when using a biphasic protocol. However, the decrease ternative exists. Iterative reconstruction algorithms should be
in aortic enhancement usually does not fall below diagnostic used where deemed appropriate to allow reduced radiation
acceptability and often remains above the 250 HU.50 Whilst the dose.57–59 For larger detector array or high-pitch dual-source
aim is to get uniform enhancement throughout the entire aorta, systems, ECG synchronization may not be necessary for motion-
but in the descending and abdominal aorta, this may on occa- free imaging of the aorta. A summary of all the protocols can be
sion be difficult to achieve. However, in most cases, the ab- seen in Table 1. Further discussions are as follows.
dominal aorta can be delineated sufficiently to visualize the
dissection and the perfusion of the mesenteric and renal arteries Single-source systems: standard detector coverage—64-
without a need for a repeat examination. Moreover, intramural and 80-detector row scanners (including “128- and
haematoma and penetrating atherosclerotic ulcer are relatively 160-slice” systems)
rare in the abdominal aorta. Multiphase injection protocols may Although, step artefact may be problematic in coronary imaging,
enable more uniform vascular enhancement throughout the this does not affect diagnostic confidence in the visualization of
entire aorta, and if available should be considered.51 the aorta. The advantage of adopting prospective triggering is
a significant reduction in radiation dose compared with non-
Optimizing CT parameters gated and retrospectively gated acquisitions. There may be a role
Although diagnosis of AAS can be made using non-gated CT for retrospective gating when the HR is fast (i.e. .100 bpm) or
techniques, image quality at the aortic root is often suboptimal in systems where the threshold for prospective triggering under
owing to motion artefact. This limits the diagnostic confidence a pre-defined HR cannot be overridden (Table 1). When ret-
and may on occasion mimic aortic dissection, leading to rospective acquisition is used, dose modulation outside the
unnecessary further investigation and treatment, including 30–80% cardiac cycle should be applied.38,60
sternotomy/thoracotomy. The prevalence of aortic motion
artefacts with non-gated CT has been reported to be high as Prospective triggering is recommended with phase selection
57–93% in some series.52–54 With ECG synchronization, the taking into account the patient’s HR.55,61,62
occurrence of this artefact is less common, allowing motion- Regular HR ,65 bpm: prospective with end-diastolic triggering.
free visualization of the aortic root and proximal coronary HR .65 bpm or irregular HR: prospective with end-systolic
arteries in almost all cases.55,56 triggering.

To allow for prospective acquisition of the aorta, systems with For scanners that cannot utilize prospective triggering in a “step-
detector coverage of at least 32 mm in the z-axis are recom- and-shoot” manner at HR .65 bpm, the following protocol
mended to make breath-holding possible during the whole scan should is recommended.
acquisition. ECG synchronization must be available to allow Regular HR ,65 bpm: prospective with end-diastolic triggering.
co-registration with heart rhythm. Scanners with $64 detector HR .65 bpm or irregular heart rate: retrospective gating with
rows should be used in conjunction with narrow reconstructed dose modulation.
slice thickness (,1 mm) in order to provide adequate multiplanar
reformats, preferably with isotropic resolution utilizing small For scanners that have a retrospective mode with adaptive dose
voxel size through the use of a small field of view tailored to modulation, this may be used as an alternative for fast HRs. This
the aorta. mode can be used to automatically tighten the dose modulation
during retrospective acquisition. However, it is worth noting
Specific protocol examples that the use of this mode should be performed with caution in
For each scanner type, it is important that dedicated protocols irregular/variable HRs, where scanner may widen the modula-
are used and optimized. The protocols outlined below should be tion window and dose may increase significantly.
used as a guide, and variations may exist depending on differing
parameters as outlined above. These protocols are advocated In addition, dose modulation outside the acquisition window
based upon expert British Society of Cardiovascular Imaging should be set at the lowest possible value if adjustable (this is
user recommendations and in collaboration with UK application vendor-specific but ranges from 4% to 20%), therefore lowering
specialists. overall dose further in retrospective acquisition.

5 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 BJR Vardhanabhuti et al

Table 1. Summary of scanning parameters for different types of CT scanners

Single source
64- and 80-detector row scanners (including “128- and 160-slice” systems)
HR , 65 Prospective gating with end-diastolic acquisition
HR . 65 Prospective gating with end-systolic acquisition
Where phase selection is not adjustable (e.g. on a scanner with prospective helical
acquisition with diastolic phase acquisition only for slow HRs)
There may be a role for retrospective gating (e.g. when the HR is .100 beats per
minute)
Exception
When retrospective acquisition is used, dose modulation outside the 30–80%
cardiac cycle should be applied
For scanners that have a retrospective mode with adaptive dose modulation, this
may be used as an alternative for fast HRs
128-, 256- or 320-detector row scanners (including “256- and 640-slice” systems)
128–256 detector rows
HR , 75 Prospective gating with end-diastolic acquisition
HR . 75 Prospective gating with end-systolic acquisition
320 detector rows
Non-gated helical acquisition with the middle 8-cm coverage (160 3 0.5 mm)
HR independent can be used to image the thoracic aorta in 1–2 heartbeats with motion-free
imaging of the aorta
If dedicated coronary assessment is required (e.g. in the context of known AAS
Exception
or a high pre-test probability), then use following
Prospectively triggered ECG synchronization with 70–80% single pulse
HR , 65
per volume
Prospectively triggered ECG synchronization with 30–80% single pulse
HR . 65
per volume
Dual source
HR-dependent prospectively ECG-synchronization protocols can be applied
HR-dependent
similar to the systems above
HR , 65 Prospective gating with end-diastolic acquisition
HR . 65 Prospective gating with end-systolic acquisition
In a system that allows for high-pitch acquisition in conjunction with wide
detector arrays, traditional ECG synchronization may not be required
e.g. a pitch of .3 and gantry rotation time 0.28 s permit coverage of
9.6–11.6 cm s21
AAS, acute aortic syndrome; ECG, electrocardiogram; HR, heart rate.

For scanner types that only use prospective helical scanning coverage of whole aorta is required, scan can be performed
during diastolic phase at HR ,65 bpm, retrospective gating craniocaudally, using ECG synchronization in the thoracic
should be used above this threshold. In this setting, the fol- portion, and then changing pitch and switching to ungated
lowing protocol is recommended. acquisition for the remaining abdominal and pelvic coverage.
Regular HR ,65 bpm: prospective helical scanning with end-
diastolic triggering. Single-source systems: broad detector coverage—
HR .65 bpm or irregular HR: retrospective gating with dose 128-, 256- or 320-detector-row scanners (including
modulation. “256- and 640-slice” systems)
For large detectors systems with increased z-axis coverage, the
Where a variable helical pitch function is available, this allows scanning time can be reduced. 128-detector-row scanners usu-
seamless switching to non-gated scanning with increased pitch ally have a detector width of 8 cm. Imaging the entire thoracic
outside the coverage for the heart. For example, for thorax only, aorta therefore requires more than one transverse section (and
one would scan variable helical pitch caudocranially. ECG syn- often 3–4 sections). It is recommended that a prospectively
chronization only used within the heart, followed by ungated triggered approach is used, as with the 64-slice scanners. Rec-
acquisition for the rest of the thorax to the apices. If extended ommendations are as follows:

6 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 Guidelines & recommendations: Recommendations for accurate CT diagnosis of AAS by BSCI/BSCCT BJR

Regular HR ,75 bpm: prospective with end-diastolic triggering. not be required.67–71 For example, using a pitch of .3 and gantry
HR .75 bpm or irregular HR: prospective with end-systolic rotation time 0.28 s permits coverage of 9.6–11.6 cm s21 with
triggering. reduced radiation dose.68,70,72

Where the ability to switch from gated to non-gated scan ac- CONCLUSION
quisition is available, this should also be utilized to mini- This document outlines the different methods of scan acquisi-
mize dose. tion with an emphasis on the importance of performing motion-
free imaging of the aorta in suspected AAS in order to provide
320-detector systems have a detector width of 16 cm; this coverage accurate diagnosis. This is by no mean an exhaustive coverage of
may be adequate to image the thoracic aorta in 1–2 rotations, and the multiple scanners available but should encompass most
with this rapid acquisition, ECG synchronization may not be re- scanners being used routinely in UK practices. It serves to
quired. Non-gated helical acquisition with the middle 8-cm cov- outline the basic principle of motion-free aortic imaging using
erage (160 3 0.5 mm) can be used to image the thoracic aorta in the currently available evidence and expert opinions of the
1–2 heartbeats with motion-free imaging of the aorta. BSCI/BSCCT. With continuing rapid advancement of CT tech-
nologies and the need to standardize image acquisition coupled
However, if dedicated coronary assessment is also required with an obligation for dose optimization, these recommenda-
(e.g. in the context of known AAS or a high pre-test probability), tions should allow centres to adopt protocols specific to their
then prospectively triggered ECG synchronization (HR ,65 bpm scanners for timely and accurate assessment using the basic
70–80% single pulse per volume, HR .65 bpm 30–80% single principles outlined in this document. Acquisition is only one
pulse per volume) covering the entire thoracic aorta should be aspect of the scan and to properly implement this imaging
performed. This will require 2 volumes of 16 cm (320 3 0.5 mm) strategy, centres must also adopt appropriate reporting facilities
for adequate coverage. Several investigators have reported sim- (e.g. picture archiving and communication system must be able
ilar protocols previously.63,64 to manage ECG-gating data sets, including handling of multi-
phasic reconstruction of retrospective acquisition), radiogra-
Dual-source systems pher’s training, as well as reporting expertise. In terms of
Dual-source systems have improved temporal resolution and implementation, it has been shown that application of ECG
thus allow higher tolerance for accelerated HRs. If temporal gating by adequately trained staff has no impact on the workflow
resolution ,100 ms can be achieved, HR-dependent prospectively of the CT examination in acute setting.73
ECG-synchronization protocols can be applied. For example, if
the HR is ,65 bpm, the optimum phase is at end diastole. For We envisage that definitive diagnosis of ascending aortic pa-
HRs .65 bpm, the optimum phase is at end systole.65,66 thology, eliminating false-positive scans, should become routine
practice and that no patient should undergo sternotomy/
In a system that allows for high-pitch acquisition in conjunction thoracotomy or other intervention without an optimal AAS
with wide detector arrays, traditional ECG synchronization may CT scan.

REFERENCES

1. Olsson C, Thelin S, Ståhle E, Ekbom A, 4. Vilacosta I, Román JA. Acute aortic syn- 8. Chiu KW, Lakshminarayan R, Ettles DF.
Granath F. Thoracic aortic aneurysm and drome. Heart 2001; 85: 365–8. doi: http://dx. Acute aortic syndrome: CT findings. Clin
dissection: increasing prevalence and im- doi.org/10.1136/heart.85.4.365 Radiol 2013; 68: 741–8. doi: http://dx.doi.
proved outcomes reported in a nationwide 5. Evangelista A, Carro A, Moral S, Teixido- org/10.1016/j.crad.2013.03.001
population-based study of more than 14,000 Tura G, Rodrı́guez-Palomares JF, Cuéllar 9. Das I, Hoey ET, Ganeshan A. Re: Acute aortic
cases from 1987 to 2002. Circulation 2006; H, et al. Imaging modalities for the syndrome: CT findings. Clin Radiol 2013; 68:
114: 2611–8. doi: http://dx.doi.org/10.1161/ early diagnosis of acute aortic e639. doi: http://dx.doi.org/10.1016/j.
CIRCULATIONAHA.106.630400 syndrome. Nat Rev Cardiol 2013; 10: crad.2013.06.012
2. Ueda T, Chin A, Petrovitch I, Fleischmann D. 477–86. doi: http://dx.doi.org/10.1038/ 10. Lempel JK, Frazier AA, Jeudy J, Kligerman SJ,
A pictorial review of acute aortic syndrome: nrcardio.2013.92 Schultz R, Ninalowo HA, et al. Aortic arch
discriminating and overlapping features as 6. Choong AM, Das S, Mulrenan N, Hamady dissection: a controversy of classification.
revealed by ECG-gated multidetector-row M, Bose P. Don’t get in a flap!: a case report Radiology 2014; 271: 848–55. doi: http://dx.
CT angiography. Insights Imaging 2012; 3: of progression through the spectrum of an doi.org/10.1148/radiol.14131457
561–71. doi: http://dx.doi.org/10.1007/ acute aortic syndrome. Vascular 2014; 22: 11. Karras R, Ricci M, Salerno TA, Gologorsky E.
s13244-012-0195-7 454–7. doi: http://dx.doi.org/10.1177/ Motion artifact resulting in a false positive
3. Maddu KK, Shuaib W, Telleria J, Johnson JO, 1708538113518203 CT angiogram for a presumed aortic dissec-
Khosa F. Nontraumatic acute aortic emer- 7. Sheikh AS, Ali K, Mazhar S. Acute aortic tion. J Card Surg 2011; 26: 223–4. doi: http://
gencies: Part 1, Acute aortic syndrome. AJR syndrome. Circulation 2013; 128: 1122–7. dx.doi.org/10.1111/j.1540-8191.2011.01200.x
Am J Roentgenol 2014; 202: 656–65. doi: doi: http://dx.doi.org/10.1161/ 12. Shanmugam G, McKeown J, Bayfield M,
http://dx.doi.org/10.2214/AJR.13.11437 CIRCULATIONAHA.112.000170 Hendel N, Hughes C. False positive

7 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 BJR Vardhanabhuti et al

computed tomography findings in aortic incidence, modes of inheritance, and phe- Spanish acute aortic syndrome study
dissection. Heart Lung Circ 2004; 13: 184–7. notypic patterns. Ann Thorac Surg 2006; 82: (RESA). Better diagnosis is not reflected in
doi: http://dx.doi.org/10.1016/j. 1400–5. doi: http://dx.doi.org/10.1016/j. reduced mortality. Revista Espe Cardiol 2009;
hlc.2004.02.003 athoracsur.2006.04.098 62: 255–62. doi: http://dx.doi.org/10.1016/
13. Raymond CE, Aggarwal B, Schoenhagen P, 19. Ascione R, Gomes WJ, Bates M, Shannon JL, S0300-8932(09)70368-9
Kralovic DM, Kormos K, Holloway D, et al. Pope FM, Angelini GD. Emergency repair of 29. Sommer T, Fehske W, Holzknecht N, Smekal
Prevalence and factors associated with false type A aortic dissection in type IV Ehlers- AV, Keller E, Lutterbey G, et al. Aortic
positive suspicion of acute aortic syndrome: Danlos syndrome. Cardiovasc Surg 2000; 8: dissection: a comparative study of diagnosis
experience in a patient population trans- 75–8. doi: http://dx.doi.org/10.1016/S0967- with spiral CT, multiplanar transesophageal
ferred to a specialized aortic treatment 2109(99)00070-8 echocardiography, and MR imaging. Radiol-
center. Cardiovasc Diagn Ther 2013; 3: 20. Germain DP. Clinical and genetic features of ogy 1996; 199: 347–52. doi: http://dx.doi.org/
196–204. doi: http://dx.doi.org/10.3978/j. vascular Ehlers-Danlos syndrome. Ann Vasc 10.1148/radiology.199.2.8668776
issn.2223-3652.2013.12.06 Surg 2002; 16: 391–7. doi: http://dx.doi.org/ 30. Nienaber CA, Spielmann RP, von Kodolitsch
14. Batra P, Bigoni B, Manning J, Aberle DR, 10.1007/s10016-001-0229-y Y, Siglow V, Piepho A, Jaup T, et al. Diagnosis
Brown K, Hart E, et al. Pitfalls in the 21. Marin A, Weir-McCall JR, Webb DJ, van of thoracic aortic dissection. Magnetic reso-
diagnosis of thoracic aortic dissection at CT Beek EJ, Mirsadraee S. Imaging of cardio- nance imaging versus transesophageal echo-
angiography. Radiographics 2000; 20: 309–20. vascular risk in patients with Turner’s cardiography. Circulation 1992; 85: 434–47.
doi: http://dx.doi.org/10.1148/radio- syndrome. Clin Radiol 2015; 70: 803–14. doi: doi: http://dx.doi.org/10.1161/01.
graphics.20.2.g00mc04309 http://dx.doi.org/10.1016/j.crad.2015.03.009 CIR.85.2.434
15. Aggarwal B, Raymond C, Jacob J, Kralovic D, 22. Milewicz DM, Dietz HC, Miller DC. Treat- 31. Clough RE, Nienaber CA. Management of
Kormos K, Holloway D, et al. Transfer of ment of aortic disease in patients with acute aortic syndrome. Nat Rev Cardiol 2015;
patients with suspected acute aortic syn- Marfan syndrome. Circulation 2005; 111: 12: 103–14. doi: http://dx.doi.org/10.1038/
drome. Am J Cardiol 2013; 112: 430–5. doi: e150–7. doi: http://dx.doi.org/10.1161/01. nrcardio.2014.203
http://dx.doi.org/10.1016/j. CIR.0000155243.70456.F4 32. Song JK. Update in acute aortic syndrome:
amjcard.2013.03.049 23. Turtle EJ, Sule AA, Webb DJ, Bath LE. Aortic intramural hematoma and incomplete dis-
16. Aggarwal B, Raymond CE, Randhawa MS, dissection in children and adolescents with section as new disease entities. J Cardiol
Roselli E, Jacob J, Eagleton M, et al. Transfer Turner syndrome: risk factors and manage- 2014; 64: 153–61. doi: http://dx.doi.org/
metrics in patients with suspected acute ment recommendations. Arch Dis Child 10.1016/j.jjcc.2014.05.005
aortic syndrome. Circ Cardiovasc Qual Out- 2015; 100: 662–6. doi: http://dx.doi.org/ 33. Harris KM, Braverman AC, Gutierrez FR,
comes 2014; 7: 780–2. doi: http://dx.doi.org/ 10.1136/archdischild-2014-307080 Barzilai B, Dávila-Román VG. Transesopha-
10.1161/CIRCOUTCOMES.114.000988 24. Chirillo F, Cavallini C, Longhini C, Ius P, geal echocardiographic and clinical features
17. Hiratzka LF, Bakris GL, Beckman JA, Bersin Totis O, Cavarzerani A, et al. Comparative of aortic intramural hematoma. J Thorac
RM, Carr VF, Casey DE Jr, et al; American diagnostic value of transesophageal echocar- Cardiovasc Surg 1997; 114: 619–26. doi:
College of Cardiology Foundation/American diography and retrograde aortography in the http://dx.doi.org/10.1016/S0022-5223(97)
Heart Association Task Force on Practice evaluation of thoracic aortic dissection. Am J 70052-7
Guidelines; American Association for Tho- Cardiol 1994; 74: 590–5. doi: http://dx.doi. 34. Song JM, Kang DH, Song JK, Kim HS, Lee
racic Surgery; American College of Radiol- org/10.1016/0002-9149(94)90749-8 CW, Hong MK, et al. Clinical significance of
ogy; American Stroke Association; Society of 25. Keren A, Kim CB, Hu BS, Eyngorina I, echo-free space detected by transesophageal
Cardiovascular Anesthesiologists; Society for Billingham ME, Mitchell RS, et al. Accuracy echocardiography in patients with type B
Cardiovascular Angiography and Interven- of biplane and multiplane transesophageal aortic intramural hematoma. Am J Cardiol
tions; Society of Interventional Radiology; echocardiography in diagnosis of typical 2002; 89: 548–51. doi: http://dx.doi.org/
Society of Thoracic Surgeons; Society for acute aortic dissection and intramural he- 10.1016/S0002-9149(01)02294-9
Vascular Medicine. 2010 ACCF/AHA/AATS/ matoma. J Am Coll Cardiol 1996; 28: 627–36. 35. Hartnell GG. Imaging of aortic aneurysms
ACR/ASA/SCA/SCAI/SIR/STS/SVM guide- doi: http://dx.doi.org/10.1016/0735-1097(96) and dissection: CT and MRI. J Thoracic
lines for the diagnosis and management of 00186-6 Imaging 2001; 16: 35–46. doi: http://dx.doi.
patients with Thoracic Aortic Disease: a re- 26. Evangelista A, Garcia-del-Castillo H, Gonzalez- org/10.1097/00005382-200101000-00006
port of the American College of Cardiology Alujas T, Dominguez-Oronoz R, Salas A, 36. Manghat NE, Morgan-Hughes GJ, Roobottom
Foundation/American Heart Association Permanyer-Miralda G, et al. Diagnosis of CA. Multi-detector row computed tomogra-
Task Force on Practice Guidelines, American ascending aortic dissection by transesophageal phy: imaging in acute aortic syndrome. Clin
Association for Thoracic Surgery, American echocardiography: utility of M-mode in rec- Radiol 2005; 60: 1256–67. doi: http://dx.doi.
College of Radiology, American Stroke ognizing artifacts. J Am Coll Cardiol 1996; 27: org/10.1016/j.crad.2005.06.011
Association, Society of Cardiovascular Anes- 102–7. doi: http://dx.doi.org/10.1016/0735- 37. Roos JE, Willmann JK, Weishaupt D, Lachat
thesiologists, Society for Cardiovascular An- 1097(95)00414-9 M, Marincek B, Hilfiker PR. Thoracic aorta:
giography and Interventions, Society of 27. Hagan PG, Nienaber CA, Isselbacher EM, motion artifact reduction with retrospective
Interventional Radiology, Society of Thoracic Bruckman D, Karavite DJ, Russman PL, et al. and prospective electrocardiography-assisted
Surgeons, and Society for Vascular Medicine. The International Registry of Acute Aortic multi-detector row CT. Radiology 2002; 222:
Circulation 2010; 121: e266–369. doi: http:// Dissection (IRAD): new insights into an old 271–7. doi: http://dx.doi.org/10.1148/
dx.doi.org/10.1161/CIR.0b013e3181d4739e disease. JAMA 2000; 283: 897–903. doi: radiol.2221010481
18. Albornoz G, Coady MA, Roberts M, Davies http://dx.doi.org/10.1001/jama.283.7.897 38. Wu W, Budovec J, Foley WD. Prospective
RR, Tranquilli M, Rizzo JA, et al. Familial 28. Evangelista A, Padilla F, López-Ayerbe J, and retrospective ECG gating for thoracic CT
thoracic aortic aneurysms and dissections– Calvo F, López-Pérez JM, Sánchez V, et al. angiography: a comparative study. AJR Am J

8 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 Guidelines & recommendations: Recommendations for accurate CT diagnosis of AAS by BSCI/BSCCT BJR

Roentgenol 2009; 193: 955–63. doi: http://dx. 48. Beeres M, Loch M, Schulz B, Kerl M, Comput Assist Tomogr 2015; 39: 196–201.
doi.org/10.2214/AJR.08.2158 Al-Butmeh F, Bodelle B, et al. Bolus timing doi: http://dx.doi.org/10.1097/
39. Harris KM, Braverman AC, Eagle KA, in high-pitch CT angiography of the aorta. RCT.0000000000000180
Woznicki EM, Pyeritz RE, Myrmel T, et al. Eur J Radiol 2013; 82: 1028–33. doi: http:// 58. Shen Y, Sun Z, Xu L, Li Y, Zhang N, Yan Z,
Acute aortic intramural hematoma: an anal- dx.doi.org/10.1016/j.ejrad.2013.01.004 et al. High-pitch, low-voltage and low-
ysis from the International Registry of Acute 49. Seifarth H, Puesken M, Kalafut JF, Wienbeck iodine-concentration CT angiography of
Aortic Dissection. Circulation 2012; 126 S, Wessling J, Maintz D, et al. Introduction of aorta: assessment of image quality and
(11 Suppl. 1): S91–6. doi: http://dx.doi.org/ an individually optimized protocol for the radiation dose with iterative reconstruction.
10.1161/CIRCULATIONAHA.111.084541 injection of contrast medium for coronary PLoS One 2015; 10: e0117469. doi: http://dx.
40. Souza D, Ledbetter S. Diagnostic errors in CT angiography. Eur Radiol 2009; 19: doi.org/10.1371/journal.pone.0117469
the evaluation of nontraumatic aortic emer- 2373–82. doi: http://dx.doi.org/10.1007/ 59. Cornfeld D, Israel G, Detroy E, Bokhari J,
gencies. Semin Ultrasound CT MR 2012; 33: s00330-009-1421-7 Mojibian H. Impact of Adaptive Statistical
318–36. doi: http://dx.doi.org/10.1053/j. 50. Behrendt FF, Bruners P, Keil S, Plumhans C, Iterative Reconstruction (ASIR) on radiation
sult.2012.02.001 Mahnken AH, Das M, et al. Effect of dose and image quality in aortic dissection
41. Kurabayashi M, Okishige K, Ueshima D, different saline chaser volumes and flow rates studies: a qualitative and quantitative analy-
Yoshimura K, Shimura T, Suzuki H, et al. on intravascular contrast enhancement in CT sis. AJR Am J Roentgenol 2011; 196:
Diagnostic utility of unenhanced computed using a circulation phantom. Eur J Radiol W336–40. doi: http://dx.doi.org/10.2214/
tomography for acute aortic syndrome. Circ J 2010; 73: 688–93. doi: http://dx.doi.org/ AJR.10.4573
2014; 78: 1928–34. doi: http://dx.doi.org/ 10.1016/j.ejrad.2009.01.008 60. Jakobs TF, Becker CR, Ohnesorge B, Flohr T,
10.1253/circj.CJ-14-0198 51. Bae KT, Tran HQ, Heiken JP. Uniform Suess C, Schoepf UJ, et al. Multislice helical
42. Hayter RG, Rhea JT, Small A, Tafazoli FS, vascular contrast enhancement and reduced CT of the heart with retrospective ECG
Novelline RA. Suspected aortic dissection contrast medium volume achieved by using gating: reduction of radiation exposure by
and other aortic disorders: multi-detector exponentially decelerated contrast material ECG-controlled tube current modulation.
row CT in 373 cases in the emergency injection method. Radiology 2004; 231: Eur Radiol 2002; 12: 1081–6. doi: http://dx.
setting. Radiology 2006; 238: 841–52. doi: 732–6. doi: http://dx.doi.org/10.1148/ doi.org/10.1007/s00330-001-1278-x
http://dx.doi.org/10.1148/radiol.2383041528 radiol.2313030497 61. Bischoff B, Hein F, Meyer T, Krebs M,
43. Lovy AJ, Bellin E, Levsky JM, Esses D, 52. Qanadli SD, El Hajjam M, Mesurolle B, Hadamitzky M, Martinoff S, et al. Compar-
Haramati LB. Preliminary development of Lavisse L, Jourdan O, Randoux B, et al. ison of sequential and helical scanning for
a clinical decision rule for acute aortic Motion artifacts of the aorta simulating radiation dose and image quality: results of
syndromes. Am J Emerg Med 2013; 31: aortic dissection on spiral CT. J Comput the prospective multicenter study on radia-
1546–50. doi: http://dx.doi.org/10.1016/j. Assist Tomogr 1999; 23: 1–6. doi: http://dx. tion dose estimates of cardiac CT angiogra-
ajem.2013.06.005 doi.org/10.1097/00004728-199901000-00001 phy (PROTECTION) I study. AJR Am J
44. Rodrigues JC, Mathias H, Negus IS, Manghat 53. Hamilton MC, Nightingale AK, Masey S, Roentgenol 2010; 194: 1495–9. doi: http://dx.
NE, Hamilton MC. Intravenous contrast Stuart AG, Angelini G, Hopkins R, et al. A doi.org/10.2214/AJR.09.3543
medium administration at 128 multidetector case report of a normal aorta misdiagnosed 62. Blanke P, Baumann T, Bulla S, Schaefer O,
row CT pulmonary angiography: bolus as type A dissection by modern multidetector Kotter E, Langer M, et al. Prospective ECG-
tracking versus test bolus and the implica- computed tomography. Eur Radiol 2010; 20: triggered CT angiography of the thoracic
tions for diagnostic quality and effective 1856–8. doi: http://dx.doi.org/10.1007/ aorta in patients with atrial fibrillation or
dose. Clin Radiol 2012; 67: 1053–60. doi: s00330-010-1748-0 accelerated heart rates: feasibility and image
http://dx.doi.org/10.1016/j.crad.2012.02.010 54. Ko SF, Hsieh MJ, Chen MC, Ng SH, Fang quality. AJR Am J Roentgenol 2010; 194:
45. Rodrigues JC, Joshi D, Lyen SM, Negus IS, FM, Huang CC, et al. Effects of heart rate on W111–4. doi: http://dx.doi.org/10.2214/
Manghat NE, Hamilton MC. Tube potential motion artifacts of the aorta on non-ECG- AJR.09.3153
can be lowered to 80 kVp in test bolus phase assisted 0.5-sec thoracic MDCT. AJR Am J 63. Hein PA, Romano VC, Lembcke A, May J,
of CT coronary angiography (CTCA) and CT Roentgenol 2005; 184: 1225–30. doi: http:// Rogalla P. Initial experience with a chest pain
pulmonary angiography (CTPA) to save dose dx.doi.org/10.2214/ajr.184.4.01841225 protocol using 320-slice volume MDCT. Eur
without compromising diagnostic quality. 55. Morgan-Hughes GJ, Owens PE, Marshall AJ, Radiol 2009; 19: 1148–55. doi: http://dx.doi.
Eur Radiol 2014; 24: 2458–66. doi: http://dx. Roobottom CA. Thoracic aorta at multi- org/10.1007/s00330-008-1255-8
doi.org/10.1007/s00330-014-3281-z detector row CT: motion artifact with 64. Li Y, Fan Z, Xu L, Yang L, Xin H, Zhang N,
46. Weininger M, Barraza JM, Kemper CA, various reconstruction windows. Radiology et al. Prospective ECG-gated 320-row CT
Kalafut JF, Costello P, Schoepf UJ. Cardio- 2003; 228: 583–8. doi: http://dx.doi.org/ angiography of the whole aorta and coronary
thoracic CT angiography: current contrast 10.1148/radiol.2282020873 arteries. Eur Radiol 2012; 22: 2432–40. doi:
medium delivery strategies. AJR Am J 56. Hofmann LK, Zou KH, Costello P, Schoepf http://dx.doi.org/10.1007/s00330-012-2497-z
Roentgenol 2011; 196: W260–72. doi: http:// UJ. Electrocardiographically gated 16-section 65. Adler G, Meille L, Rohnean A, Sigal-Cin-
dx.doi.org/10.2214/AJR.10.5814 CT of the thorax: cardiac motion suppres- qualbre A, Capderou A, Paul JF. Robustness
47. Kim DJ, Kim TH, Kim SJ, Kim DP, Oh CS, sion. Radiology 2004; 233: 927–33. doi: of end-systolic reconstructions in coronary
Ryu YH, et al. Saline flush effect for http://dx.doi.org/10.1148/radiol.2333030826 dual-source CT angiography for high heart
enhancement of aorta and coronary 57. Caywood D, Paxton B, Boll D, Nelson R, Kim rate patients. Eur Radiol 2010; 20: 1118–23.
arteries at multidetector CT coronary C, Lowry C, et al. Effects of model-based doi: http://dx.doi.org/10.1007/s00330-009-
angiography. Radiology 2008; 246: 110–5. iterative reconstruction on image quality for 1642-9
doi: http://dx.doi.org/10.1148/ low-dose computed tomographic angiogra- 66. Seifarth H, Wienbeck S, Püsken M, Juergens
radiol.2453061953 phy of the thoracic aorta in a swine model. J KU, Maintz D, Vahlhaus C, et al. Optimal

9 of 10 birpublications.org/bjr Br J Radiol;89:20150705
 BJR Vardhanabhuti et al

systolic and diastolic reconstruction windows 69. Blanke P, Bulla S, Baumann T, Siepe M, (TAVI) using a high-pitch spiral acquisi-
for coronary CT angiography using dual- Winterer JT, Euringer W, et al. Thoracic tion mode. Eur Radiol 2012; 22: 51–8. doi:
source CT. AJR Am J Roentgenol 2007; 189: aorta: prospective electrocardiographically http://dx.doi.org/10.1007/s00330-011-
1317–23. doi: http://dx.doi.org/10.2214/ triggered CT angiography with dual-source 2233-0
AJR.07.2711 CT—feasibility, image quality, and dose 72. Flohr TG, Leng S, Yu L, Aiimendinger T,
67. Alkadhi H, Stolzmann P, Desbiolles L, reduction. Radiology 2010; 255: 207–17. Bruder H, Petersilka M, et al. Dual-source
Baumueller S, Goetti R, Plass A, et al. Low- doi: http://dx.doi.org/10.1148/ spiral CT with pitch up to 3.2 and 75 ms
dose, 128-slice, dual-source CT coronary radiol.09090860 temporal resolution: image reconstruction
angiography: accuracy and radiation dose of 70. Karlo C, Leschka S, Goetti RP, Feuchtner G, and assessment of image quality. Med Phys
the high-pitch and the step-and-shoot mode. Desbiolles L, Stolzmann P, et al. High-pitch 2009; 36: 5641–53. doi: http://dx.doi.org/
Heart 2010; 96: 933–8. doi: http://dx.doi.org/ dual-source CT angiography of the aortic 10.1118/1.3259739
10.1136/hrt.2009.189100 valve-aortic root complex without ECG- 73. Schertler T, Glücker T, Wildermuth S, Jungius
68. Beeres M, Schell B, Mastragelopoulos A, synchronization. Eur Radiol 2011; 21: KP, Marincek B, Boehm T. Comparison of
Herrmann E, Kerl JM, Gruber-Rouh T, et al. 205–12. doi: http://dx.doi.org/10.1007/ retrospectively ECG-gated and nongated
High-pitch dual-source CT angiography of s00330-010-1907-3 MDCT of the chest in an emergency setting
the whole aorta without ECG synchronisa- 71. Wuest W, Anders K, Schuhbaeck A, May regarding workflow, image quality, and di-
tion: initial experience. Eur Radiol 2012; 22: MS, Gauss S, Marwan M, et al. Dual source agnostic certainty. Emerg Radiol 2005; 12:
129–37. doi: http://dx.doi.org/10.1007/ multidetector CT-angiography before 19–29. doi: http://dx.doi.org/10.1007/s10140-
s00330-011-2257-5 transcatheter aortic valve implantation 005-0435-y

10 of 10 birpublications.org/bjr Br J Radiol;89:20150705