Koen Nieman

New coronary imaging techniques: what to expect?

Coronary imaging is the ultimate challenge. During the last decade there have been great advances in this imaging technique, partly as a result of improved scanner hardware, but more because of advances in microprocessor technologynnCoronary imaging is the ultimate challenge for any imaging technique. This is because the coronary arteries are small (2–4 mm in diameter) and have a tortuous, complex, three dimensional course and are continuously in motion, except for a short period during mid diastole.nnDuring the last decade we have witnessed great advances in cardiac imaging. This was partly as a result of improved scanner hardware, but more because of advances in microprocessor technology, which allow for rapid processing of extremely large quantities of data necessary for the acquisition, post-processing, and construction of hitherto unimaginable, non-invasively obtained images of the coronary lumen and plaque.nnThis raises two important questions. Firstly, has progress in non-invasive coronary imaging techniques gone so far that conventional invasive diagnostic coronary angiography has become redundant? Secondly, are these new imaging techniques capable of detecting which coronary plaque is stable, unstable or vulnerable?nnMagnetic resonance coronary angiography (MR-CA), electron beam computed tomography (EBCT), and multi-slice computed tomography (MS-CT) have recently emerged as new non-invasive diagnostic techniques that possess the potential to replace conventional diagnostic angiography.1–4 The diagnostic accuracy to detect a significant coronary stenosis is presented in table 1. However, it should be noted that: firstly, the diagnostic value only concerns the detection of stenoses in the proximal and mid segment of the coronary tree, because the smaller distal segments cannot be adequately visualised; and secondly, only in 70–80 % of these proximal and mid segments is image quality sufficient to allow a semiquantitative assessment.nnView this table:nn Table 1 nApproximate diagnostic value of non-invasive coronary imaging techniques to detect significant coronary stenosis (> 50 % …

Non-invasive coronary artery imaging with electron beam computed tomography and magnetic resonance imaging

ecent developments in hardware and software have increased the diagnostic capabilities of magnetic resonance imaging (MRI) and electron beam computed tomography (EBT) to visualise the cardiac anatomy, including the coronary arteries. Visualisation of the heart puts any diagnostic technique to the test, because the continuous cardiac motion distorts the image and high temporal resolution is required to “freeze” the heart to produce a sharp image. In particular, non-invasive visualisation of the coronary arteries is diYcult because of the small size of the coronary arteries (2‐5 mm in diameter), the complex, tortuous course making it often impossible to “catch” the coronary artery in one slice (tomogram), and the cardiac and respiratory motion causing loss of sharpness or motion artefacts. In this article image acquisition and processing techniques of MRI and EBT will be presented. The clinical role of both techniques in cardiac imaging will be discussed, together with a brief introduction of the technical aspects.

Strategies for radiation dose reduction in nuclear cardiology and cardiac computed tomography imaging: a report from the European Association of Cardiovascular Imaging (EACVI), the Cardiovascular Committee of European Association of Nuclear Medicine (EANM) and the European Society of Cardiovascular Radiology (ESCR)

nuclear cardiology and cardiac computed tomography imaging: a report from the European Association of Cardiovascular Imaging (EACVI), the Cardiovascular Committee of European Association of Nuclear Medicine (EANM), and the European Society of Cardiovascular Radiology (ESCR) Alessia Gimelli*, Stephan Achenbach, Ronny R. Buechel, Thor Edvardsen, Marco Francone, Oliver Gaemperli, Marcus Hacker, Fabien Hyafil, Philipp A. Kaufmann, Patrizio Lancellotti, Koen Nieman, Gianluca Pontone, Francesca Pugliese, Hein J. Verberne, Matthias Gutberlet, Jeroen J. Bax, and Danilo Neglia

Images in cardiovascular medicine. Detection of a vulnerable coronary plaque: a treatment dilemma.

A 34-year-old man who experienced a 30-minute episode of chest pain at rest was admitted to the coronary care unit after becoming symptom free. His ECG was normal. A few hours later, he suffered a 5-minute period of recurrent chest pain with transient ST-segment elevation (Figure 1). The level of creatine phosphokinase reached its peak at 800 IU (upper limit=199 IU), and the maximum troponin T level was 1.85 μg/L. Noninvasive coronary imaging with a 16-slice spiral computed tomography scanner (MSCT) (Sensation 16, Siemens AG; Forchheim, Germany) suggested a nonobstructive lesion in the mid-left anterior descending artery (LAD) (Figure 2), which was confirmed with coronary angiography. Coronary spasm was excluded by methergin provocation test, which only showed general vasoconstriction (31% reduction of reference diameter) but no focal spasm. Intravascular ultrasound (IVUS) (CVIS Atlantis 40-MHz 3F catheter, Boston Scientific, TOMTEC ECG-gated acquisition system) demonstrated a local plaque with vessel remodeling in the mid-LAD. The plaque was covered by a thin layer of speckling, which was different from the plaque and …

Diagnostic Accuracy of a Machine-Learning Approach to Coronary Computed Tomographic Angiography–Based Fractional Flow Reserve: Result From the MACHINE Consortium

Background: Coronary computed tomographic angiography (CTA) is a reliable modality to detect coronary artery disease. However, CTA generally overestimates stenosis severity compared with invasive angiography, and angiographic stenosis does not necessarily imply hemodynamic relevance when fractional flow reserve (FFR) is used as reference. CTA-based FFR (CT-FFR), using computational fluid dynamics (CFD), improves the correlation with invasive FFR results but is computationally demanding. More recently, a new machine-learning (ML) CT-FFR algorithm has been developed based on a deep learning model, which can be performed on a regular workstation. In this large multicenter cohort, the diagnostic performance ML-based CT-FFR was compared with CTA and CFD-based CT-FFR for detection of functionally obstructive coronary artery disease. Methods and Results: At 5 centers in Europe, Asia, and the United States, 351 patients, including 525 vessels with invasive FFR comparison, were included. ML-based and CFD-based CT-FFR were performed on the CTA data, and diagnostic performance was evaluated using invasive FFR as reference. Correlation between ML-based and CFD-based CT-FFR was excellent (R=0.997). ML-based (area under curve, 0.84) and CFD-based CT-FFR (0.84) outperformed visual CTA (0.69; P<0.0001). On a per-vessel basis, diagnostic accuracy improved from 58% (95% confidence interval, 54%–63%) by CTA to 78% (75%–82%) by ML-based CT-FFR. The per-patient accuracy improved from 71% (66%–76%) by CTA to 85% (81%–89%) by adding ML-based CT-FFR as 62 of 85 (73%) false-positive CTA results could be correctly reclassified by adding ML-based CT-FFR. Conclusions: On-site CT-FFR based on ML improves the performance of CTA by correctly reclassifying hemodynamically nonsignificant stenosis and performs equally well as CFD-based CT-FFR.

Is there still a role for cardiac CT in the emergency department in the era of highly-sensitive troponins?

Physicians practicing cardiovascular medicine are every day confronted with patients presenting with symptoms suggestive of an acute coronary syndrome (ACS). Over the years, there have been substantial technical advances, such as the introduction of new non-invasive imaging techniques and the introduction of new highly sensitive cardiac biomarkers. Physicians have adopted these new assets and have become more experienced with them thus improving medical care. Nevertheless, the search for an efficient, yet safe diagnostic work-up for patients presenting with symptoms suggestive of ACS is ongoing. A large proportion of patients will require some form of non-invasive testing and the choice for the diagnostic modality as well as its timing are important steps in this process. Cardiac computed tomography (CT), a non-invasive imaging technique that rapidly provides visualization of the coronary artery tree, is an attractive option, with its unparalleled negative predictive value for obstructive coronary artery disease (CAD). With the introduction of highly-sensitive troponins (hsTn), the role of non-invasive testing, including cardiac CT, has changed. This review will provide an oversight on what is known about cardiac CT in acute chest presentations. Furthermore, we will discuss the changing role of cardiac CT in the era of hsTn and the possibility of their combined use in the work-up of suspected ACS patients. hsTn is currently an established tool for the diagnosis and triage of patients with suspected ACS. The role of cardiac CT has shifted now to a secondary, comprehensive rule-out test in patients with inconclusive biomarker status, providing information on stenosis severity, plaque burden, high-risk features and the presence of other serious conditions that can also give rise to hsTn.

Calcium Imaging in the Emergency Department: Between a Rock and a Hard Place

The triage of patients with acute chest pain is a clinical challenge encountered by physicians on a daily basis. It is also a logistic challenge, associated with long periods of observation and monitoring, contributes to overcrowding of emergency rooms, and is associated with substantial cost. Coronary computed tomographic (CT) angiography has long been considered a means to improve diagnostic uncertainty and alleviate the logistic burden in the triage of acute chest pain. During the past decade, a series of randomized clinical trials have tested the value of cardiac CT for patients with low–intermediate risk chest complaints and demonstrated that in comparison with standard care or specific other diagnostic tests, CT angiography is equally safe but can permit substantially earlier hospital discharge.1–7 Although CT angiography has an excellent negative predictive value, there is a reciprocal tendency to overestimate the angiographic and hemodynamic severity of coronary artery disease, particularly in patients with high calcium scores. Consequently, CT is associated with more diagnostic and therapeutic invasive procedures,8 blunting the potential for cost saving. Based on these observations, the question emerges whether CT angiography is equally effective in patients with a high atherosclerotic burden and whether the test should perhaps be avoided in patients with extensive coronary calcification.nnSee Article by Bittner et al nnIn this issue of Circulation: Cardiovascular Imaging , Bittner et al9 combined data from the ACRIN-PA-4005 (American College of Radiology Imaging Network, Pennsylvania Department of Health-4005) and the ROMICAT-II (Rule Out Myocardial Ischemia/Infarction Using Computer Assisted Tomography-II) trials,2,3 to investigate the association between the …

Cardiac CT Before and After Bypass Graft Surgery

Because of their size and limited mobility, bypass grafts can be visualized well by cardiac CT. Compared with invasive angiography, its diagnostic accuracy in detecting graft failure is very good. Advantages of cardiac CT are its ability to image the grafts without selective contrast injection and to depict their anatomy in relation to the structures around the heart. The clinical utility of cardiac CT is currently limited by its inability to assess the functional significance of obstructive disease.

Intermodality variation of aortic dimensions: How, where and when to measure the ascending aorta

BACKGROUNDnNo established reference-standard technique is available for ascending aortic diameter measurements. The aim of this study was to determine agreement between modalities and techniques.nnnMETHODSnIn patients with aortic pathology transthoracic echocardiography, computed tomography angiography (CTA) and magnetic resonance angiography (MRA) were performed. Aortic diameters were measured at the sinus of Valsalva (SoV), sinotubular junction (STJ) and tubular ascending aorta (TAA) during mid-systole and end-diastole. In echocardiography both the inner edge-to-inner edge (I-I edge) and leading edge-to‑leading edge (L-L edge) methods were applied, and the length of the aortic annulus to the most cranial visible part of the ascending aorta was measured. In CTA and MRA the I-I method was used.nnnRESULTSnFifty patients with bicuspid aortic valve (36u202f±u202f13u202fyears, 26% female) and 50 Turner patients (35u202f±u202f13u202fyears) were included. Comparison of all aortic measurements showed a mean difference of 5.4u202f±u202f2.7u202fmm for the SoV, 5.1u202f±u202f2.0u202fmm for the STJ and 4.8u202f±u202f2.1u202fmm for the TAA. The maximum difference was 18u202fmm. The best agreement was found between echocardiography L-L edge and CTA during mid-systole. CTA and MRA showed good agreement. A mean difference of 1.5u202f±u202f1.3u202fmm and 1.8u202f±u202f1.5u202fmm was demonstrated at the level of the STJ and TAA comparing mid-systolic with end-diastolic diameters. The visible length of the aorta increased on average 5.3u202f±u202f5.1u202fmmW during mid-systole.nnnCONCLUSIONSnMRA and CTA showed best agreement with L-L edge method by echocardiography. In individual patients large differences in ascending aortic diameter were demonstrated, warranting measurement standardization. The use of CTA or MRA is advised at least once.

Round-the-clock performance of coronary CT angiography for suspected acute coronary syndrome: Results from the BEACON trial

AbstractObjectiveTo assess the image quality of coronary CT angiography (CCTA) for suspected acute coronary syndrome (ACS) outside office hours.MethodsPatients with symptoms suggestive of an ACS underwent CCTA at the emergency department 24 hours, 7 days a week. A total of 118 patients, of whom 89 (75 %) presented during office hours (weekdays between 07:00 and 17:00) and 29 (25 %) outside office hours (weekdays between 17:00 and 07:00, weekends and holidays) underwent CCTA. Image quality was evaluated per coronary segment by two experienced readers and graded on an ordinal scale ranging from 1 to 3.ResultsThere were no significant differences in acquisition parameters, beta-blocker administration or heart rate between patients presenting during office hours and outside office hours. The median quality score per patient was 30.5 [interquartile range 26.0–33.5] for patients presenting during office hours in comparison to 27.5 [19.75–32.0] for patients presenting outside office hours (p=0.043). The number of non-evaluable segments was lower for patients presenting during office hours (0 [0–1.0] vs. 1.0 [0–4.0], p=0.009).ConclusionImage quality of CCTA outside office hours in the diagnosis of suspected ACS is diminished.Key Points• Quality scores were higher for coronary-CTA during office hours.n • There were no differences in acquisition parameters.n • There was a non-significant trend towards higher heart rates outside office hours.n • Coronary-CTA on the ED requires state-of-the-art scanner technology and sufficiently trained staff.n • Coronary-CTA on the ED needs preparation time and optimisation of the procedure.