Introduction
An overview of the most relevant papers in the International Journal of Cardiovascular
Imaging over the year 2016 for the different modalities. Relatively few manuscripts
in the field of X-ray imaging were published in 2016. The far majorities were in MSCT,
MRI and echocardiography, followed by nuclear cardiology and intravascular imaging,
of which the last one is not included in this overview.
X-ray imaging
Author He et al. described the use of the Myocardial Perfusion Frame Count (TMPFC)
technique as an indicator to predict left ventricular systolic dysfunction in the
sub-acute phase of STEMI [1]. They counted the number of frames from the first appearance
of myocardial blush beyond the infarct related artery until the frame when contrast
or myocardial blush disappeared; frame rate was either 15 or 30 f/sec. The ROC curves
identified a cut-off of 94 frames for TMPFC to differentiate between normal and abnormal
wall motion score index by echo-strain parameters in the subacute phase of STEMI.
A randomized comparison of fluoroscopic techniques for implanting pacemaker leads
on the right ventricular outflow tract (RVOT) septum was described by Chen et al.
[2]. |They evaluated the accuracy of the combination of standard fluoroscopic and
left lateral (LL) fluoroscopic views for the determination of RVOT septal positions
compared with standard views alone in a total of 143 patients. They found that the
success rate of RVOT septal position in the group with three standard fluoroscopic
views plus left lateral fluoroscopic views was significantly higher than in the standard
group (p = 0.029).
The team of Starek et al. tested various acquisition protocols for the right atrium
and the left atrium to create 3D models of the atria and esophagus using 3D rotational
angiography [3]. They concluded that 3D rotational angiography is a reliable method
that supports catheter ablation of complex atrial arrhythmias. The left atrial protocol
with esophagus imaging was significantly more reliable than the right atrial protocol,
which may be negatively affected by high BMI. Another rotational angiography based
paper was published by Rodriguez-Olivares et al., in which they studied the determinants
of image quality for on-line assessment of frame geometry after TAVI [4]. They used
dedicated research prototype software for motion compensation without rapid ventricular
pacing after the implantation of four commercially available catheter-based valves.
They concluded that this specific solution with motion compensation offers good image
quality, bit it was negatively affected by certain valve types, presence of artefacts
and higher BMI.
Another topic that received attention was longitudinal stent deformation and the longer
term clinical outcomes [5]. Guler et al. concluded that the use of extra-support guiding
catheter, extra-support guidewires and low stent inflation pressure increases the
occurrence of longitudinal stent deformation. But with proper treatment, unwanted
long-term outcomes can be successfully prevented.
Timmins et al. compared in a very small cohort of patients (n = 5) with non-obstructive
coronary artery disease biplane angiographic versus intravascular ultrasound derived
reconstructed coronary geometries, assessed wall shear stress and the association
of wall shear stress and CAD progression after 6 months [6]. They concluded from this
limited set a strong agreement between angiographic and IVUS-derived coronary geometries,
but limited agreement was observed between computed wall shear stress values and associations
of wall shear stress with CAD progression.
Donmet et al. studied in a population of 81 patients the changes over time in non-culprit
lesions in patients wih ST segment elevated myocardial infarction using QCA [7]. They
found that in approximately 50% of the cases, the non-culprit lesions were found less
critical during control angiography when compared to primary PCI. And therefore, they
suggest that complete revascularization during primary PCI should be avoided in multi-vessel
STEMI patients and critical non culprit artery lesions should be re-evaluated with
later control angiography.
Nuclear cardiology
In 2016 different excellent paper in the field of nuclear cardiology were published
in the journal. In this review we selected a few papers on technical advances, atherosclerosis
imaging, imaging in heart failure and FDG PET/CT imaging in infective endocarditis.
Technical advances
Perfusion SPECT imaging may be technically challenging in obese patients and data
on its prognostic value in the obese are rather scarce. De Lorenzo et al. [8] studied
365 obese patients among 1396 patients referred for single-day rest/stress perfusion
imaging using a dedicated multipinhole cadium-zinc telluride (CTZ) SPECT camera. Image
quality was good/excellent in 94.5% of these obese patients. The annualized mortality
rates were not significantly different among obese and non-obese patients, being <1%
with normal CTZ-SPECT and increased with the degree of scan abnormality in both obese
and non-obese patients. Obesity itself was nog an independent predictor of death.
The authors conclude that single-day stress/rest CTZ-SPECT with a multipinhole camera
provides prognostic information with high image quality in obese patients.
High efficiency CZT cameras provide also an opportunity to lower the injected activities
of radiopharmaceuticals for SPECT myocardial imaging. Kincl et al. [9] evaluated the
feasibility of ultra-low dose Thallium stress-redistribution including prone imaging
in obese patients using a CZT camera. They studied 124 patients with an ultra-low
dose Thallium of 0.5 MBq/kg. The mean administered activity was 39.2 ± 7 MBq for non-obese
and 48.7 ± 6 for obese patients (p < 0.0001) and the calculated effective dose was
4.0 ± 0.7 and 4.9 ± 0.6 mSv respectively (p < 0.0001) or a 50% radiation reduction
in comparison with previous studies using CZT cameras. Further analysis showed that
these ultra-low dose Thallium stress-redistribution protocol, including post-stress
prone imaging, provided good quality of images with excellent interobserver variability
both in obese and non-obese patients.
Atherosclerosis imaging
Several excellent reviews on the topics of atherosclerosis and multi-modality imaging
were published in 2016. FDG-PET has shown promise in detecting metabolically active
inflammatory cell infiltrates associated with vulnerable atherosclerotic plaque. In
contrast to previous ex vivo studies incuatong plaque specimens with FDG after excision,
Liu et al. [10] investigated which plaque components contribute to enhanced FDG uptake
in vivo. They utilized high-resolution micro-PET on carotid plaques excised from 14
patients, injected with FDG just prior to carotid endarterectomy. The results of this
very nice study indicate that in vivo uptake of FDG corresponded to regions of inflammatory
cell infiltrate in human carotid atherosclerotic plaque, particularly, complex inflammatory
cell infiltrated with co-localized macrophages, lymphocytes and foam cells. The use
of high-resolution micro-PET also revealed FDG uptake in other plaque components such
as loose extracellular matrix and neovasculature. The overlay of FDG-PET signal with
serially sectioned and matched histology validated that FDG uptake had good correlation
with the active components of the human atherosclerotic plaque.
Imaging in heart failure
Left ventricular dyssynchrony (LVD) is an independent predictor of adverse cardiovascular
events and progression to heart failure. It can also be potentially corrected with
cardiac resynchronization therapy. LVD can be diagnosed using phase analysis on myocardial
perfusion imaging with ECG-gated SPECT. Tavares et al. [11] evaluated clinical, electrocardiographic
and scintigraphic data from 1000 patients who underwent MPI with ECG-gated SPECT.
The Emory Cardiac Toolbox software was used for phase analysis and LVD was diagnosed
based on the following criteria: standard deviation of LV phase distribution ≥ 43°
and/or phase histogram ≥ 140° in the resting and/or stress phase of the examination.
Although the phase analysis parameters were greater at rest, both phases could be
used for diagnosis. Multivariate analysis revelead that that male sex, obesity, history
of CAD and QRS interval ≥ 120 ms were independently associated with LVD. The overall
prevalence of LVD was 6.5%, and it reached 42% in the presence of certain risk factors.
Although this study clearly indicate that LVD evaluation with nuclear imaging is feasible
and frequently present, its prognostic value and impact on device therapy needs further
evaluation.
FDG PET/CT imaging in prosthetic valve endocarditis
Recent studies have shown promising results using (18)F-FDG PET/CT for the diagnosis
of prosthetic valve endocarditis (PVE) and the use of this nuclear imaging technique
has been recently advocated in American and European guidelines on the management
of endocarditis. However, negative controls were usually lacking in these studies.
Fagman et al. [12] compared (18)F-FDG uptake around prosthetic aortic valves in 8
patients with definite PVE to the (18)F-FDG uptake in 19 patients with an aortic prosthesis
without PVE. Visual analysis showed a sensitivity of 75%, specificity of 87%, positive
likelihood ratio of 4.8 and negative likelihood ratio of 0.3. Semi quantitative analysis
using maximal standardized uptake values (SUV) in the valve area and in the descending
aorta showed an area under the curve of 0.90 (95% CI 0.74–1.0) using ROC-curve analysis
for the SUV-ratio. The authors concluded that (18)F-FDG uptake in the prosthetic valve
area had an overall good diagnostic performance in the diagnosis of PVE.
Echocardiography
In the 2016 edition of the International Journal of Cardiovascular Imaging several
interesting studies were published in the field of cardiac ultrasound. Some of them
are discussed in this overview.
Grading of diastolic function by echocardiography
The American and European scientific echo community have published an algorithm for
the grading of diastolic function. However, the ability to use this algorithm effectively
in daily clinical practice has not been investigated. Van Dalen et al. hypothesized
that in some patients it may be difficult to grade diastolic dysfunction with this
scheme, since there may be discrepancies in the assessed parameters [13]. The ASE/EAE
algorithm starts with assessment of diastolic myocardial wall velocities and left
atrial volumes with subsequent assessment of E/A ratio, E-wave deceleration time and
pulmonary venous flow. The aim of the current study was to test the feasibility of
the ASE/EAE algorithm and to compare this with a new “Thoraxcenter” algorithm. The
Thoraxcenter algorithm reverses these steps, uses left atrial dimension instead of
volume and does not include a Valsalva manoeuvre and pulmonary venous flow. Due to
inconsistencies between diastolic myocardial wall velocities and left atrial volumes
and a not covered E/A ratio in the range of 1.5–2 it was not possible to classify
48% of patients with the ASE/EAE algorithm, as opposed to only 10% by the Thoraxcenter
algorithm. Left atrial volume was always needed in the ASE/EAE algorithm. In only
64% of patients left atrial size was necessary by the Thoraxcenter algorithm. When
left atrial volume would have been used instead of left atrial dimension, grading
of LV diastolic function would have been different in only 2% of patients without
apparent improvement. Assessment of left atrial dimension was considerably faster
than left atrial volume. The Thoraxcenter algorithm to grade LV diastolic dysfunction
was - compared to the ASE/EAE algorithm - simpler, faster, better reproducible and
yields a higher diagnostic outcome.
Left atrial minimum volume versus left atrial maximum volume to assess left ventricular
filling
Previous data have demonstrated that left atrial (LA) minimum volume indexed for body
surface area (LAVImin) is more strongly associated with the Doppler echocardiographic
E/e′ ratio than LA maximum volume index (LAVImax). Hedberg et al. sought to explore
if LAVImin was more closely related to serum levels of NT-proBNP than LAVImax and
E/e′ in the community [14]. A community-based sample of 730 subjects underwent echocardiographic
examinations and NT-proBNP measurements. Age, LAVImin, LAVImax, estimated glomerular
filtration rate and E/e′ were strongly correlated with log-NT-proBNP. In a multiple
linear regression model with log-NT-proBNP as dependent variable and LAVImin, LAVImax,
E/e′ ratio, and potential confounders as predictors, an adjusted R2 of 44.9% was obtained.
When excluding either of LAVImin or E/e′ the model fit was significantly reduced.
In contrast, when LAVImax was excluded the model fit was preserved. To detect an NT-proBNP
level of >125 ng/L, LAVImin yielded a significantly larger area under the receiver
operating characteristic curve than LAVImax and E/e′. In this community-based sample,
LAVImin was more strongly associated with NT-proBNP than LAVImax. Moreover, the discriminatory
power to detect an elevated NT-proBNP level was stronger in LAVImin than in LAVImax
and E/e′. These findings support previous data that LAVImin may be more closely related
to left ventricular filling function than LAVImax.
Is 3-dimensional transoesophageal echocardiography superior for the evaluation of
mitral valve prolapse ?
De Groot-de Laat et al. assessed the incremental value of two-dimensional and three-dimensional
transoesophageal echocardiography over two-dimensional transthoracic echocardiography
in three reader groups with different expertise (novice, trainees, cardiologists)
in a total of twenty patients and five healthy persons [15]. Overall there was an
improvement in agreement and Kappa values from novice to trainees to cardiologists.
Diagnostic accuracies of 2D-transoesophageal echocardiography were higher than those
of 2D-transthoracic echocardiography mainly in novice readers. Time to diagnosis was
dramatically reduced from 2D- to 3D-transoesophageal echocardiography in all reader
groups. 3D-transoesophageal echocardiography also improved the agreement (+12 to +16%)
and Kappa values (+0.14 to +0.21) in all reader groups for the exact description of
P2 prolapse. Differences between readers with variable experience in determining the
precise localization and extent of the prolapsing posterior mitral valve scallops
exist in particular in 2D- transthoracic echocardiography analysis. 3D-transoesophageal
echocardiography analysis was extremely fast compared to the 2D analysis methods and
showed the best diagnostic accuracy (mainly driven by specificity) with identification
of P1 and P3 prolapse still improving from novice to trainees to cardiologists and
provided optimal description of P2 prolapse extent.
Best approach to evaluate paravalvular regurgitation after transcatheter aortic valve
implantation using transthoracic echocardiography
Paravalvular leak after transcatheter aortic valve implantation (TAVI) is challenging
to quantitate. Transthoracic echocardiography is the main tool used for the assessment
of paravalvular leak but is modestly reproducible. Abdelghani et al. sought to develop
a reproducible echocardiographic approach to assess paravalvular leak in the post-TAVI
setting [16]. Four observers independently analyzed eleven parameters of paravalvular
severity in 50 pre-discharge echo studies performed after TAVI. Inter and intra-observer
intraclass correlation coefficients were highest and coefficient of variation lowest
for jet circumferential extent, jet origin breadth, jet qualitative features in long-axis
views, jet time velocity integral and pressure half time. Combining color Doppler
and continuous wave Doppler parameters in a granular algorithm yielded excellent reproducibility
of paravalvular leakage assessment by transthoracic echocardiography.
Global longitudinal strain for the early detection of ventricular dysfunction in patients
with repaired aortic coarctation
Despite successful aortic coarctation (CoA) repair, systemic hypertension often recurs
which may influence left ventricular function. Menting et al. aimed to detect early
left ventricular dysfunction using left ventricular global longitudinal strain (GLS)
in adults with repaired CoA, and to identify associations with patient and echocardiographic
characteristics [17]. In this cross-sectional study, patients with repaired CoA and
healthy controls were recruited prospectively. Left ventricular GLS was lower in patients
than in controls (−17.1 ± 2.3 vs. −20.2 ± 1.6%, P < 0.001). Eighty percent of the
patients had a normal left ventricular ejection fraction, but GLS was still lower
than in controls (P < 0.001). In patients, GLS correlated with systolic and diastolic
blood pressure, QRS duration, left atrial dimension, left ventricular mass and left
ventricular ejection fraction. Patients with either associated cardiac lesions, multiple
cardiac interventions or aortic valve replacement had lower GLS than patients without.
Although the majority of adults with repaired CoA seem to have a normal systolic left
ventricular function, left ventricular GLS was decreased. Higher blood pressure, associated
cardiac lesions, and larger left atrial dimension are related with lower GLS. Therefore,
left ventricular GLS may be used as objective criterion for early detection of ventricular
dysfunction.
Longitudinal strain-volume/area relationships in athletes
Oxborough et al. simultaneously assessed longitudinal strain and left ventricular
volume/ right ventricular area in 92 male athletes subdivided according to varying
sporting demographics [18]. Athletes with a high static–high dynamic profile have
greater resting longitudinal contribution to volume change in the left ventricle which,
in part, is related to an increased wall thickness. A lower longitudinal contribution
to area change in the right ventricle is also apparent in these athletes.
Contrast-enhanced ultrasound
Schinkel et al. wrote an interesting overview on the role of contrast-enhanced ultrasound
(CEUS) in the evaluation of patients with known or suspected atherosclerosis [19].
CEUS is a high-resolution, noninvasive imaging modality, which is safe and may benefit
patients with coronary, carotid, or aortic atherosclerosis. The administration of
a micro-bubble contrast agent in conjunction with ultrasound results in an improved
image quality and provides information that cannot be assessed with standard B-mode
ultrasound. CEUS allows a reliable assessment of endocardial borders, left ventricular
function, intracardiac thrombus and myocardial perfusion. CEUS results in an improved
detection of carotid atherosclerosis, and allows assessment of high-risk plaque characteristics
including intra-plaque vascularization, and ulceration. CEUS provides real-time bedside
information in patients with a suspected or known abdominal aortic aneurysm or aortic
dissection. The absence of ionizing radiation and safety of the contrast agent allow
repetitive imaging which is particularly useful in the follow-up of patients after
endovascular aneurysm repair. New developments in CEUS-based molecular imaging will
improve the understanding of the pathophysiology of atherosclerosis and may in the
future allow to image and directly treat cardiovascular diseases (theragnostic CEUS).
Familiarity with the strengths and limitations of CEUS may have a major impact on
the management of patients with atherosclerosis.
Magnetic resonance imaging
There were a number of interesting advancements in cardiovascular MRI (CMR) in 2016.
Reval et al. [20] studied patients with left bundle branch block for mechanical features
of dyssynchrony and found to more frequently have septal flash, apical rocking, and
delayed aortic opening relative to end-diastole and pulmonic valve opening. The delayed
aortic valve opening was found to be positively correlated with QRS duration and negatively
correlated with ejection fraction. Hu et al. [21] found that the level of Galectin-3
added prognostic value over late gadolinium enhancement (LGE) in patients with non-ischemic
cardiomyopathy. Left ventricular wall thickness was compared in patients with hypertrophic
cardiomyopathy and echocardiography [22]. Echocardiography was found to measure greater
thickness than CMR. Contrast echocardiography was more similar in thickness. Pozo
et al. [23] found that early gadolinium enhancement was a common feature in patients
with hypertrophic cardiomyopathy even in the absence of late gadolinium enhancement.
Wu et al. [24] found that quantitative diffusion-weighted CMR was a feasible alterative
to extra cellular volume for characterizing the extent of fibrosis in patients with
hypertrophic cardiomyopathy. CMR was found able to detect cardiac involvement in patients
with active eosinophilic granulomatosis even when cardiac symptoms were not present
[25].
Improved border sharpness of post infarct scar was demonstrated by Rutz et al. [26]
with a self-navigator 3D whole heart pulse sequence. In a series of 647 asymptomatic
subjects, Nham et al. [27] found that silent myocardial infarction was not independently
associated with ventricular mass, geometry and function, whereas it was associated
with diabetes mellitus. The feasibility of three dimensional fusion of electromechanical
mapping and LGE CMR for real-time intramyocardial cell injections in a porcine model
was established [28].
The prognostic value of stenosis class as measured by magnetic resonance angiography
over traditional risk factors in patients with peripheral arterial disease was demonstrated
by van den Bosch et al. [29]. Improved in vitro visualization of the lumen in peripheral
nitinol stents was found using off-resonance magnetic resonance angiography compared
with T1-weighted acquisition [30]. Li and Wang [31] found a poor correlation for plaque
lipid content to the contralateral carotid artery suggesting local effects for the
development of high-risk lesions. Aortic stiffness in patients with systemic lupus
erythematosus and rheumatoid arthritis was studied by CMR [32].
Faletti et al. [33] found that CMR could be used reliably for aortic annulus sizing
compared with computed tomography and transesophageal echocardiography. The prognostic
value of T1-mapping to derive extra-cellular volume was demonstrated in patients receiving
transcatheter aortic valve implantation (TAVI) [34]. The blood flow characteristic
in the ascending aorta were assess in patients following TAVI and compared with patients
following stented aortic bioprostheses [35]. It was found that the latter had significantly
more extensive vertical and helical flow patterns than either TAVI or controls.
The performance of an accelerated CMR protocol using iterative SENSE reconstruction
and spatio-temporal L1-regularization (IS SENSE) was demonstrated [36]. In related
work, Bogachkov et al. [37] used this technique for right ventricular assessment.
A 3D-Dixon based method was developed for measuring epicardial and pericardial fat
volumes [38].
The feasibility of heart deformation analysis for measuring regional myocardial velocity
with CMR was tested in normal volunteers [39]. Cardiac strains as measured by applying
feature tracking to CMR images were found to be significantly impaired in patients
with acute myocarditis [40]. Kawakubo et al. [41] found that a semi-automatic longitudinal
strain analysis useful for evaluating LV and RV dysfunction for a variety of pathologies.
Markl et al. [42] performed 4D flow MRI in patients with atrial fibrillation reduced
mean velocities and higher stasis compared with controls. In other work, the relationship
between left atrial appendage emptying and left atrial function was compared with
the presence of left atrial spontaneous echogenic contrast on transesophageal echocardiography
in patients with atrial fibrillation [43]. Good qualitative grading of aortic regurgitation
was found for 4D flow comparted with echocardiography [44].
A dose correction for post-contrast T1 mapping of the heart was proposed by Gai et
al. [45] and applied to subjects in the MESA study. Increased T1 values were found
in athletes having ≥ 5 years of sports activity compared with controls suggesting
the development of myocardial fibrosis [46]. Increased native T1-values were found
at the interventricular insertion points of patients with precapillary pulmonary hypertension
[47].
A semi-automated cardiac segmentation tool was found to improve the reproducibility
and speed of right heart MRA [48].Knowledge-based reconstruction was found to be useful
for CMR volumetry of the right ventricle after arterial switch for dextro-transposition
of the great arteries [49]. Ghelani at al [50] compared echocardiography and CMR based
strain analysis of functional single ventricles and found good intra-modality reproducibility,
but inter-modality was only modest.
Computed tomography
In 2016 a large number of original articles, covering a variety of topics related
to CT, were submitted to the journal and underwent a rigorous review/selection process.
While the submission, review, and editorial selection process has well-known biases,
the articles published reflect current trends in computed tomography.
Coronary artery disease
Coronary artery disease is a major focus of cardiac CT. While clinical prevention
guidelines suggest a limited role, coronary calcium scoring (CAC) remains a topic
of ongoing research. Published papers describe the effective radiation exposure among
participants from the MESA cohort [51], and discuss modifications of acquisition technique
to allow further dose reduction, e.g. using iterative model based reconstruction [52].
Other studies examined the association between CV risk factors and coronary calcification
in different patient populations [53–55].
In contrast to CAC, which identifies only calcified plaque, contrast-enhanced CTA
can assess overall plaque burden and plaque characteristics. While it is not an indication
for CTA itself, plaque burden is evaluated by experienced clinical readers in coronary
CTA indicated for suspected obstructive CAD and is a topic of significant interest
in research. Published papers describe a correlation between elevated HBA1c and higher
frequency of obstructive CAD and vulnerable atherosclerotic coronary plaque characteristics
(positive vessel remodeling and low-attenuation plaques) in patients with type 2 diabetes
[56, 57] An outcome study evaluated prognostic value of coronary CTA (composite endpoint
of all-cause mortality, nonfatal myocardial infarction, and unstable angina requiring
hospitalization) in a cohort of diabetic patients without known CAD, and a control
group without diabetes [58]. Multivariate analysis showed significant prognostic value
in diabetic patients over Framingham Score for plaque segment involvement score (SIS)
and the segment stenosis score (SSS), while Coronary artery calcium score (CACS) did
not add prognostic value in this cohort.
Based on the experience with invasive coronary angiography as well as CTA, the limitations
of luminal stenosis assessment for the prediction of hemodynamic significance of CAD
are well known. CT techniques to evaluate lesion functional significance are therefore
a major focus of research. Among them, non-invasive fractional flow reserve measured
by coronary computed tomography angiography (FFRCT) has gained significant interest.
One published study examined the feasibility of FFRCT in a small ‘unselected’ cohort
of patients with suspected significant CAD [59]. FFRCTcould be measured in the majority
of consecutive, patients who had suspected significant CAD by CCTA and demonstrated
good diagnostic performance for detecting hemodynamically significant CAD even in
patients with calcified vessels. Another important study demonstrated the impact of
image resolution on geometrical reconstruction and subsequent FFR calculation with
invasive and CT FFR [60]. Disagreement was found in 17.5% vessels. The difference
between FFRCTA and FFRQCA correlated with the deviation between minimal lumen areas
by CCTA and by ICA. Another parameter of functional coronary lesion significance is
myocardial perfusion. A published study evaluated the ability of adenosine stress
computed tomography perfusion (CTP) findings to predict mid-term major adverse cardiac
events (MACE) (cardiac death, non-fatal myocardial infarction and revascularizations)
in patients with acute-onset chest pain, but normal electrocardiograms and troponins
[61]. After adjustment for the pretest probability of obstructive coronary artery
disease, both detection of a PD and stress TPR were significantly associated with
MACE. Other studies demonstrated the feasibility of four-dimensional (4D) whole-heart
computed tomography perfusion (CTP) of the myocardium [62] and the ability of cardiac
CT for the evaluation of myocardial delayed enhancement (MDE) in the assessment of
patients with cardiomyopathy, compared to cardiac MRI [63].
Clinical indications for coronary CTA in patients with known advance obstructive disease
are limited, but CT has a defined role in the early evaluation of new coronary stent
systems. A pre-clinical study evaluated visualization of polymeric bioresorbable scaffolds
(BRSs) by micro-computed tomography (mCT) in a coronary bifurcation model [64]. The
translucent structure of the bioresorbable scaffold allows evaluation the coronary
lumen with coronary CTA. A clinical study evaluated the accuracy of coronary CTA for
in-scaffold quantitative evaluation with optical coherence tomography (OCT) as a reference
[65]. In the scaffolded segment, coronary CTA underestimated minimal lumen area by
about 10%. Another study evaluated prevalence and clinical implication of stent fracture
and longitudinal compression in first- and new-generation drug-eluting stents (DES)
using coronary computed tomography angiography (CCTA) [66]. Lastly a study compared
costs and clinical outcomes of invasive versus non-invasive diagnostic evaluations
for patients with suspected in-stent restenosis (ISR) after percutaneous coronary
intervention [67].
Structural and valvular heart disease intervention
An important focus of CT are indications in the context of structural heart disease
intervention. For TAVR planning, one study evaluated an automatic aortic root landmarks
detection method with automated determination of annulus radius, annulus orientation,
and distance from annulus plane to right and left coronary ostia [68]. Other studies
describe the use of CT in the context of LAA occlusion. Left atrial appendage (LAA)
structure and morphology was compared between real-time three-dimensional transesophageal
echocardiography (RT3D-TEE) and enhanced cardiac computed tomography (CT) [69]. Bland–Altman
analysis demonstrated that the LAA measurements obtained using RT3D-TEE were lower
than those obtained with the CT.
Software development and data analysis
Exciting progress is described in analysis of CT data. Published studies examined
quantitative semi-automated methods for assessment of coronary luminal stenosis severity
[70] and fully-automated techniques for the extraction of the entire arterial access
route from the femoral artery to the aortic root for TAVR evaluation [71] or the carotid
arteries in CTA in the thorax and upper neck region [72]. Other studies examined subtraction
CCTA in the evaluation of in-stent restenosis [73] and fusion of 3D echocardiography
(3DE) with multidetector computed tomography (MDCT) to correlate territorial longitudinal
strain (LS) with coronary stenosis [74]. The role of dual-energy CT angiography (DE-CTA)
for imaging of the aorta was evaluated [75]. Other studies described a non-invasive
approach for in vivo assessment of endothelial shear stress (ESS) ESS by coronary
computed tomography angiography (CTA) potentially allowing combined local hemodynamic
and plaque morphologic information for risk stratification in patients with coronary
artery disease [76]. Lastly a study investigated the use of artificial neural networks
(ANN) to improve risk stratification and prediction of MPI and angiographic results
[77].
The above selection of published articles about cardiovascular CT reflects current
clinical use and research interests. Use of CT, like any other diagnostic test, has
to balance anticipated benefit against potential risk, specifically for CT radiation
exposure and contrast administration. This risk assessment takes into account the
susceptibility of specific patient populations [78, 79]. The journal will continue
to offer a platform for rapid publication of high-quality research in the field of
cardiovascular imaging.