Rapid and complete coronary arterial tree visualization with magnetic resonance imaging: feasibility and diagnostic performance

Motion robust coronary MR angiography using zigzag centric ky-kz trajectory and high-resolution deep learning reconstruction

PURPOSE

To develop a new MR coronary angiography (MRCA) technique by employing a zigzag fan-shaped centric ky-kz k-space trajectory combined with high-resolution deep learning reconstruction (HR-DLR).

METHODS

All imaging data were acquired from 12 healthy subjects and 2 patients using two clinical 3-T MR imagers, with institutional review board approval. Ten healthy subjects underwent both standard 3D fast gradient echo (sFGE) and centric ky-kz k-space trajectory FGE (cFGE) acquisitions to compare the scan time and image quality. Quantitative measures were also performed for signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as sharpness of the vessel. Furthermore, the feasibility of the proposed cFGE sequence was assessed in two patients. For assessing the feasibility of the centric ky-kz trajectory, the navigator-echo window of a 30-mm threshold was applied in cFGE, whereas sFGE was applied using a standard 5-mm threshold. Image quality of MRCA using cFGE with HR-DLR and sFGE without HR-DLR was scored in a 5-point scale (non-diagnostic = 1, fair = 2, moderate = 3, good = 4, and excellent = 5). Image evaluation of cFGE, applying HR-DLR, was compared with sFGE without HR-DLR. Friedman test, Wilcoxon signed-rank test, or paired t tests were performed for the comparison of related variables.

RESULTS

The actual MRCA scan time of cFGE with a 30-mm threshold was acquired in less than 5 min, achieving nearly 100% efficiency, showcasing its expeditious and robustness. In contrast, sFGE was acquired with a 5-mm threshold and had an average scan time of approximately 15 min. Overall image quality for MRCA was scored 3.3 for sFGE and 2.7 for cFGE without HR-DLR but increased to 3.6 for cFGE with HR-DLR and (p < 0.05). The clinical result of patients obtained within 5 min showed good quality images in both patients, even with a stent, without artifacts. Quantitative measures of SNR, CNR, and sharpness of vessel presented higher in cFGE with HR-DLR.

CONCLUSION

Our findings demonstrate a robust, time-efficient solution for high-quality MRCA, enhancing patient comfort and increasing clinical throughput.

Diagnostic accuracy of whole heart coronary magnetic resonance angiography: a systematic review and meta-analysis

BACKGROUND

The purpose of this meta-analysis was to comprehensively investigate the diagnostic ability of 1.5 T and 3.0 T whole heart coronary angiography (WHCA) to detect significant coronary artery disease (CAD) on X-ray coronary angiography.

METHODS

A literature search of electronic databases, including PubMed, Web of Science Core Collection, Cochrane advanced search, and EMBASE, was performed to retrieve and integrate articles showing significant CAD detectability of 1.5 and 3.0 T WHCA.

RESULTS

Data from 1899 patients from 34 studies were included in the meta-analysis. 1.5 T WHCA had a summary area under ROC of 0.88 in the patient-based analysis, 0.90 in the vessel-based analysis, and 0.92 in the segment-based analysis. These values for 3.0 T WHCA were 0.94, 0.95, 0.96, respectively. Contrast-enhanced 3.0 T WHCA had significantly higher specificity than non-contrast-enhanced 1.5 T WHCA on a patient-based analysis (0.87, 95% CI 0.80-0.92 vs. 0.74, 95% CI 0.64-0.82, P = 0.02). There were no differences in diagnostic performance on a patient-based analysis by use of vasodilators, beta-blockers or between Asian and Western countries.

CONCLUSIONS

The diagnostic performance of WHCA was deemed satisfactory, with contrast-enhanced 3.0 T WHCA exhibiting higher specificity compared to non-contrast-enhanced 1.5 T WHCA in a patient-based analysis. There were no significant differences in diagnostic performance on a patient-based analysis in terms of vasodilator or beta-blocker use, nor between Asian and Western countries. However, further large-scale multicentre studies are crucial for the widespread global adoption of WHCA.

Clinical impact of cardiac magnetic resonance in patients with suspected coronary artery disease associated with chronic kidney disease (AQUAMARINE-CKD study): study protocol for a randomized controlled trial

Background

Although screening for coronary artery disease (CAD) using computed tomography coronary angiography in patients with stable chest pain has been reported to be beneficial, patients with chronic kidney disease (CKD) might have limited benefit due to complications of contrast agent nephropathy and decreased diagnostic accuracy as a result of coronary artery calcifications. Cardiac magnetic resonance (CMR) has emerged as a novel imaging modality for detecting coronary stenosis and high-risk coronary plaques without contrast media that is not affected by coronary artery calcification. However, the clinical use of this technology has not been robustly evaluated.

Methods

AQUAMARINE-CKD is an open parallel-group prospective multicenter randomized controlled trial of 524 patients with CKD at high risk for CAD estimated based on risk factor categories for a Japanese urban population (Suita score) recruited from 6 institutions. Participants will be randomized 1:1 to receive a CMR examination that includes non-contrast T1-weighted imaging and coronary magnetic angiography (CMR group) or standard examinations that include stress myocardial scintigraphy (control group). Randomization will be conducted using a web-based system. The primary outcome is a composite of cardiovascular events at 1 year after study examinations: all-cause death, death from CAD, nonfatal myocardial infarction, nonfatal ischemic stroke, and ischemia-driven unplanned coronary intervention (percutaneous coronary intervention or coronary bypass surgery).

Discussion

If the combination of T1-weighted imaging and coronary magnetic angiography contributes to the risk assessment of CAD in patients with CKD, this study will have major clinical implications for the management of patients with CKD at high risk for CAD.

Trial registration

Japan Registry of Clinical Trials (jRCT) 1,052,210,075. Registered on September 10, 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06820-w.

Multimodalities Imaging of Immunoglobulin 4-related Cardiovascular Disorders

Immunoglobulin 4 (IgG4)-related systemic disease (IgG4-RSD) is a systemic inflammatory disease characterized by elevation of serum IgG4. IgG4-RSD can affect any organ in the body, and the list of organs associated with this condition is growing steadily. IgG4-related cardiovascular disease affects the coronary arteries, heart valves, myocardium, pericardium, aorta, pulmonary and peripheral vessels. Echocardiography is the most commonly used non-invasive imaging method. Computed tomography angiography (CTA) can assess aortitis, periarteritis and coronary aneurysms. Coronary CTA is fast, offers high spatial resolution and a wide coverage field of view. Cardiac magnetic resonance imaging (CMR) offers a comprehensive evaluation of the cardiovascular system including cardiac function, extent of myocardial fibrosis, characterise cardiac masses with different pulse sequences and guide to further treatment. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) can provide important information about the extent of disease, the presence of active inflammation and the optimum biopsy site. In general, the role of diagnostic imaging includes establishing the diagnosis, detecting complications, guiding biopsy and documenting response to therapy.

Recent Advances in Cardiac Magnetic Resonance Imaging

Cardiac magnetic resonance (CMR) imaging provides accurate anatomic information and advanced soft contrast, making it the reference standard for assessing cardiac volumes and systolic function. In this review, we summarize the recent advances in CMR sequences. New technical development has widened the use of CMR imaging beyond the simple characterization of myocardial scars and assessment of contractility. These novel CMR sequences offer comprehensive assessments of coronary plaque characterization, myocardial fiber orientation, and even metabolic activity, and they can be readily applied in clinical settings. CMR imaging is able to provide new insights into understanding the pathophysiologic process of underlying cardiac disease, and it can help physicians choose the best treatment strategies. Although several limitations, including the high cost and time-consuming process, have limited the widespread clinical use of CMR imaging so far, recent advances in software and hardware technologies have made the future more promising.

Follow-up of coronary artery patency after implantation of bioresorbable coronary scaffolds: The emerging role of magnetic coronary artery imaging

Bioresorbable vascular scaffolds (BVSs) represent the newest tool in the treatment of coronary artery disease (CAD). Conversely to the previous metal stents and thanks to the polylactate-based backbone, BVSs could be visualized by magnetic resonance imaging (MRI) without artifacts. These properties allow a potential non-invasive assessment of coronary artery patency after percutaneous coronary intervention (PCI), avoiding cardiac catheterization included iodine contrast and radiation exposure, and potentially more sophisticated imaging tool as the optical coherence tomography (OCT). We reviewed the available medical literature on the coronary MRI evaluation of BVS after PCI, also discussing its potential diagnostic role in the long-term follow-up of these patients.

Effect of Nitroglycerin on the Performance of MR Coronary Angiography

PURPOSE

To systematically investigate the effect of sublingual glyceryl trinitrate (nitroglycerin=nitro=glyceryl trinitrate=GTN=C₃ H₅ N₃ O₉ [NTG]) on the diagnostic performance of MR coronary artery imaging (MRCA) to detect relevant coronary artery disease (CAD).

MATERIALS AND METHODS

Thirty-five healthy volunteers and 25 patients with suspected or proven CAD (all in sinus rhythm) underwent MRCA before and after NTG using a contrast-agent free, three-dimensional, navigator-based, steady state free precession acquisition (voxel size 1.0 × 0.7 × 0.7 mm³ ) at 1.5 Tesla. Target parameters were stenosis detection (>50%), visible vessel length (straightened planar reconstruction) and vessel diameter (curved planar reconstruction, measured proximal/medial/distal). In patients, invasive coronary angiography served as reference.

RESULTS

NTG led to increase of the coronary diameter both in healthy volunteers (right coronary artery [RCA]: 3.2 to 3.7 mm, P < 0.001; left anterior descending coronary artery [LAD]: 2.9 to 3.4 mm, P = 0.009; left circumflex coronary artery [LCx]: 2.8 to 3.3 mm, P < 0.001) and patients (RCA 3.5 to 4.0 mm, P = 0.01; LAD 3.3 to 3.7 mm, P = 0.008; LCx: 2.9 to 3.3 mm, P = 0.03). Visible vessel length increased after NTG for the LAD (volunteers: 72 to 84 mm, P = 0.03; patients: 56 to 78 mm, P = 0.01) and for LCx (volunteers: 48 to 60 mm, P = 0.02). Sensitivity to detect > 50% stenosis improved after NTG from 88.0 to 96%, specificity from 46.5 to 69.8%, diagnostic accuracy from 61.8 to 79.4% and positive/negative predictive value from 48.9 to 64.9% and 87.0 to 96.8%, respectively.

CONCLUSION

Sublingual administration of NTG significantly enhanced the visibility of the coronary arteries and improved the detection of coronary artery stenosis.

LEVEL OF EVIDENCE

2 J. MAGN. RESON. IMAGING 2017;45:1419-1428.

Cardiovascular magnetic resonance in rheumatology: Current status and recommendations for use

Targeted therapies in connective tissue diseases (CTDs) have led to improvements of disease-associated outcomes, but life expectancy remains lower compared to general population due to emerging co-morbidities, particularly due to excess cardiovascular risk. Cardiovascular magnetic resonance (CMR) is a noninvasive imaging technique which can provide detailed information about multiple cardiovascular pathologies without using ionizing radiation. CMR is considered the reference standard for quantitative evaluation of left and right ventricular volumes, mass and function, cardiac tissue characterization and assessment of thoracic vessels; it may also be used for the quantitative assessment of myocardial blood flow with high spatial resolution and for the evaluation of the proximal coronary arteries. These applications are of particular interest in CTDs, because of the potential of serious and variable involvement of the cardiovascular system during their course. The International Consensus Group on CMR in Rheumatology was formed in January 2012 aiming to achieve consensus among CMR and rheumatology experts in developing initial recommendations on the current state-of-the-art use of CMR in CTDs. The present report outlines the recommendations of the participating CMR and rheumatology experts with regards to: (a) indications for use of CMR in rheumatoid arthritis, the spondyloarthropathies, systemic lupus erythematosus, vasculitis of small, medium and large vessels, myositis, sarcoidosis (SRC), and scleroderma (SSc); (b) CMR protocols, terminology for reporting CMR and diagnostic CMR criteria for assessment and quantification of cardiovascular involvement in CTDs; and (c) a research agenda for the further development of this evolving field.

Contribution of cardiovascular magnetic resonance in the evaluation of coronary arteries

Cardiovascular magnetic resonance (CMR) allows the nonradiating assessment of coronary arteries; to achieve better image quality cardiorespiratory artefacts should be corrected. Coronary MRA (CMRA) at the moment is indicated only for the detection of abnormal coronary origin, coronary artery ectasia and/or aneurysms (class I indication) and coronary bypass grafts (class II indication). CMRA utilisation for coronary artery disease is not yet part of clinical routine. However, the lack of radiation is of special value for the coronary artery evaluation in children and women. CMRA can assess the proximal part of coronary arteries in almost all cases. The best results have been observed in the evaluation of the left anterior descending and the right coronary artery, while the left circumflex, which is located far away from the coil elements, is frequently imaged with reduced quality, compared to the other two. Different studies detected an increase in wall thickness of the coronaries in patients with type I diabetes and abnormal renal function. Additionally, the non-contrast enhanced T1-weighed images detected the presence of thrombus in acute myocardial infarction. New techniques using delayed gadolinium enhanced imaging promise the direct visualization of inflamed plaques in the coronary arteries. The major advantage of CMR is the potential of an integrated protocol offering assessment of coronary artery anatomy, cardiac function, inflammation and stress perfusion-fibrosis in the same study, providing an individualized clinical profile of patients with heart disease.

Quantitative analysis of 1.5-T whole-heart coronary MR angiograms obtained with 32-channel cardiac coils: a comparison with conventional quantitative coronary angiography

PURPOSE

To develop a method to determine significant stenosis at whole-heart coronary magnetic resonance (MR) angiography and to evaluate the accuracy and reproducibility of this approach.

MATERIALS AND METHODS

The institutional review board approved the study, and all participants provided written informed consent. Sixty-two patients who were suspected of having coronary artery disease (CAD) and were scheduled for conventional coronary angiography were included. Coronary MR angiography was performed by using a 1.5-T imager with 32-channel coils. Luminal narrowing was evaluated with quantitative analysis (QA) of coronary MR angiograms on the basis of the signal intensity profile along the vessel. Percentage stenosis with QA of coronary MR angiograms was calculated as [1 - (SI(min)/SI(ref))] × 100, where SI(min) is minimal signal intensity and SI(ref) is corresponding reference signal intensity. Diagnostic performance of QA of coronary MR angiograms for predicting at least a 50% reduction in diameter was evaluated by using quantitative coronary angiography (QCA), with conventional angiography findings serving as the reference standard. Receiver operating characteristic (ROC) analysis, Spearman rank correlation, Bland-Altman analysis, and Cohen κ analysis were used.

RESULTS

The areas under the ROC curve in a segment-based analysis for detecting significant CAD were 0.96 (95% confidence interval [CI]: 0.94, 0.98) with QA of coronary MR angiograms and 0.93 (95% CI: 0.88, 0.98) with visual assessment. The correlation coefficients between percentage stenosis with QA of coronary MR angiograms and percentage stenosis with QCA were 0.84 (P < .001), 0.80 (P < .001), and 0.66 (P < .001) in the patient-, vessel-, and segment-based analyses, respectively.

CONCLUSION

QA of coronary MR angiograms with use of a signal intensity profile along the vessel permits detection of CAD. This method had a diagnostic performance approximately equal to that of visual analysis of coronary MR angiograms with high inter- and intraobserver reliability, allowing for more objective interpretation of coronary MR angiography findings.

Diagnostic performance of non-contrast-enhanced whole-heart magnetic resonance coronary angiography in combination with adenosine stress perfusion cardiac magnetic resonance imaging

BACKGROUND

We sought to evaluate the diagnostic performance of 1.5-T non-contrast enhanced whole-heart magnetic resonance coronary angiography (MRCA) alone and in combination with adenosine stress cardiac magnetic resonance imaging (CMR-Perf). MRCA has been proposed to allow for detection of coronary artery disease (CAD). Yet, recent studies failed to show an incremental value of MRCA when added to CMR-Perf.

METHODS

Non-Gadolinium 1.5-T contrast-enhanced, electrocardiogram-triggered, navigator-gated free-breathing MRCA was performed in 144 patients (pts) with suspected or known CAD. Accuracy of MRCA in detecting CAD was evaluated using X-ray coronary angiography as the reference. A novel algorithm was used to combine the results of MRCA and CMR-Perf.

RESULTS

MRCA was diagnostic in 96/144 pts (67%) with regular breathing (mean age 62.5 ± 13); 77% of all coronary segments (939/1226) and 92% of segments suitable for percutaneous coronary intervention (792/866) were assessable. In 59 pts a novel algorithm to combine MRCA and CMR-Perf was performed with high diagnostic performance: accuracy, sensitivity, specificity, negative and positive predictive values were 91.5% (54/59; 95% CI, 84%-99%), 95.7% (22/23; 77-100), 88.9% (32/36; 74-96), 84.6% (22/26; 71-99), and 97.0% (32/33; 91-100). Compared to the combined use of CMR-Perf and late gadolinium enhancement, specificity with the novel algorithm significantly increased (P = .008).

CONCLUSION

MRCA has a high assessability in segments suitable for percutaneous coronary intervention in pts with regular breathing. The combined use of MRCA and CMR-Perf improved specificity for the detection of significant CAD.

Respiratory self-navigated postcontrast whole-heart coronary MR angiography: initial experience in patients

PURPOSE

To assess the diagnostic performance of respiratory self-navigation for whole-heart coronary magnetic resonance (MR) angiography in a patient cohort referred for diagnostic cardiac MR imaging.

MATERIALS AND METHODS

Written informed consent was obtained from all participants for this institutional review board-approved study. Self-navigated coronary MR angiography was performed after administration of a contrast agent in 78 patients (mean age, 48.5 years ± 20.7 [standard deviation]; 53 male patients) referred for cardiac MR imaging because of coronary artery disease (n = 40), cardiomyopathy (n = 14), congenital anomaly (n = 17), or "other" (n = 7). Examination duration was recorded, and the image quality for each coronary segment was assessed with consensus reading. Vessel sharpness, length, and diameter were measured. Quantitative values in proximal, middle, and distal segments were compared by using analysis of variance and t tests. A double-blinded comparison with the results of x-ray angiography was performed when such results were available.

RESULTS

When patients with different indications for cardiac MR imaging were examined with self-navigated postcontrast coronary MR angiography, whole-heart data sets with 1.15-mm isotropic spatial resolution were acquired in an average of 7.38 minutes ± 1.85. The main and proximal coronary segments could be visualized in 92.3% of cases, while the middle and distal segments could be visualized in 84.0% and 55.8% of cases, respectively. Subjective scores and vessel sharpness were significantly higher in the proximal segments than in the middle and distal segments (P < .05). Anomalies of the coronary arteries could be confirmed or excluded in all cases. Per-vessel sensitivity and specificity for stenosis detection were 64.7% and 85.0%, respectively, in the 31 patients for whom reference standard x-ray coronary angiography results were available.

CONCLUSION

The self-navigated coronary MR angiography sequence shows promise for coronary imaging. However, technical improvements are needed to improve image quality, especially in the more distal coronary segments.

Additive value of magnetic resonance coronary angiography in a comprehensive cardiac magnetic resonance stress-rest protocol for detection of functionally significant coronary artery disease: a pilot study

BACKGROUND

Cardiovascular magnetic resonance (CMR) myocardial perfusion imaging (MPI) is a state-of-the-art noninvasive modality for detection of myocardial ischemia and coronary artery disease. Magnetic resonance coronary angiography (MRCA) allows visualization of the coronary tree, but its incremental value as part of a CMR protocol including MPI and late gadolinium enhancement (LGE) is not well established. We aimed to evaluate the additive diagnostic value of a 3-dimensional whole-heart MRCA integration into a 1.5T CMR-MPI/LGE protocol for the detection of functionally significant coronary artery disease.

METHODS AND RESULTS

Forty-three symptomatic patients (61 ± 8.3 years; 65% men) with suspected coronary artery disease and intermediate/high-pretest probability underwent CMR (including CMR-MPI, MRCA, and LGE) and x-ray invasive coronary angiography (XA) with fractional flow reserve evaluation. Diagnostic performances of MRCA, CMR-MPI/LGE, and MRCA+CMR-MPI/LGE integration were determined having XA+fractional flow reserve as standard for coronary artery disease (≥90% stenosis/occlusion or fractional flow reserve ≤ 0.80 in vessels>2 mm). MRCA inclusion into the CMR protocol was associated with a mean increase of 7.9 ± 4.69 (0-17.7) minutes in total examination duration (14%). On patient-based analysis, MRCA had 96% sensitivity, 68% specificity, positive predictive value of 79%, and negative predictive value of 93%. CMR-MPI/LGE had 79% sensitivity, 95% specificity, positive predictive value of 95%, and negative predictive value of 78%. Integration of MRCA with CMR-MPI/LGE further improved CMR performance to 96% sensitivity, 89% specificity, positive predictive value of 92%, and negative predictive value of 94%, with a global accuracy of 93%.

CONCLUSIONS

In this intermediate/high-pretest population, integration of noncontrast-enhanced whole-heart MRCA nonsignificantly improved per-patient diagnostic accuracy of a comprehensive 1.5-T stress-rest CMR-MPI/LGE protocol at a cost of longer scanning times.

Towards a five-minute comprehensive cardiac MR examination using highly accelerated parallel imaging with a 32-element coil array: feasibility and initial comparative evaluation

PURPOSE

To evaluate the feasibility and perform initial comparative evaluations of a 5-minute comprehensive whole-heart magnetic resonance imaging (MRI) protocol with four image acquisition types: perfusion (PERF), function (CINE), coronary artery imaging (CAI), and late gadolinium enhancement (LGE).

MATERIALS AND METHODS

This study protocol was Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board-approved. A 5-minute comprehensive whole-heart MRI examination protocol (Accelerated) using 6-8-fold-accelerated volumetric parallel imaging was incorporated into and compared with a standard 2D clinical routine protocol (Standard). Following informed consent, 20 patients were imaged with both protocols. Datasets were reviewed for image quality using a 5-point Likert scale (0 = non-diagnostic, 4 = excellent) in blinded fashion by two readers.

RESULTS

Good image quality with full whole-heart coverage was achieved using the accelerated protocol, particularly for CAI, although significant degradations in quality, as compared with traditional lengthy examinations, were observed for the other image types. Mean total scan time was significantly lower for the Accelerated as compared to Standard protocols (28.99 ± 4.59 min vs. 1.82 ± 0.05 min, P < 0.05). Overall image quality for the Standard vs. Accelerated protocol was 3.67 ± 0.29 vs. 1.5 ± 0.51 (P < 0.005) for PERF, 3.48 ± 0.64 vs. 2.6 ± 0.68 (P < 0.005) for CINE, 2.35 ± 1.01 vs. 2.48 ± 0.68 (P = 0.75) for CAI, and 3.67 ± 0.42 vs. 2.67 ± 0.84 (P < 0.005) for LGE. Diagnostic image quality for Standard vs. Accelerated protocols was 20/20 (100%) vs. 10/20 (50%) for PERF, 20/20 (100%) vs. 18/20 (90%) for CINE, 18/20 (90%) vs. 18/20 (90%) for CAI, and 20/20 (100%) vs. 18/20 (90%) for LGE.

CONCLUSION

This study demonstrates the technical feasibility and promising image quality of 5-minute comprehensive whole-heart cardiac examinations, with simplified scan prescription and high spatial and temporal resolution enabled by highly parallel imaging technology. The study also highlights technical hurdles that remain to be addressed. Although image quality remained diagnostic for most scan types, the reduced image quality of PERF, CINE, and LGE scans in the Accelerated protocol remain a concern.

Heart involvement in rheumatoid arthritis: multimodality imaging and the emerging role of cardiac magnetic resonance

OBJECTIVES

Patients with rheumatoid arthritis (RA) exhibit a high risk of cardiovascular disease (CVD). CVD in RA can present in many guises, commonly detected at a subclinical level only.

METHODS

Modern imaging modalities that allow the noninvasive assessment of myocardial performance and are able to identify cardiac abnormalities in early asymptomatic stages may be useful tools in terms of screening, diagnostic evaluation, and risk stratification in RA.

RESULTS

The currently used imaging techniques are echocardiography, single-photon emission computed tomography (SPECT), and cardiac magnetic resonance (CMR). Between them, echocardiography provides information about cardiac function, valves, and perfusion; SPECT provides information about myocardial perfusion and carries a high amount of radiation; and CMR-the most promising imaging modality-evaluates myocardial function, inflammation, microvascular dysfunction, valvular disease, perfusion, and presence of scar. Depending on availability, expertise, and clinical queries, "right technique should be applied for the right patient at the right time."

CONCLUSIONS

In this review, we present a short overview of CVD in RA focusing on the clinical implication of multimodality imaging and mainly on the evolving role of CMR in identifying high-risk patients who could benefit from prevention strategies and early specific treatment targeting the heart. Advantages and disadvantages of each imaging technique in the evaluation of RA are discussed.

Acquired coronary disease in children: the role of multimodality imaging

Coronary sequelae of Kawasaki disease, post-surgical coronary lesions and cardiac allograft vasculopathy are the main causes of acquired coronary pathology in childhood. Surveillance and timely recognition of coronary problems in children who are at risk of ischemic events are imperative and noninvasive imaging is increasingly utilized for these purposes. Herein, we summarize the causes of acquired coronary disease in children and discuss the role of various imaging techniques that are available to establish the diagnosis and guide management.

Effects of respiratory motion on coronary wall MR imaging: a quantitative study of older adults

The aim of the present study is to assess the effects of respiratory motion on the image quality of two-dimensional (2D), free-breathing, black-blood coronary wall magnetic resonance (MR) imaging. This study was compliance with the HIPPA. With the approval of the institution review board, 230 asymptomatic participants, including 164 male patients (72.9 ± 4.4 years) and 66 female patients (72.4 ± 5.1 years), were recruited. Written informed consent was obtained. A 2D navigator (NAV)-gated, black-blood coronary wall MR imaging sequence was run on the left main artery, the left anterior descending artery and the right coronary artery. The drift of the location of the NAV and scan efficiency were compared between good (scored 2 or 3) and poor images (scored 1). Age, body weight, body weight index, heart rate, length of the rest period of cardiac motion, diaphragm excursion and breathing frequency were compared using a t test between the "successful" (having 2 or 3 good images) and "unsuccessful" cases (having 1 or 0 good images). A logistic regression model was applied to identify the contributors to good image quality. The drift of the NAV location and the scan efficiency were higher in the 411 good images compared with the 279 poor images. Minimal drift of the NAV location and low body weight were identified as independent predictors of good images after using a logistic regression model to adjust for multiple physiological and technical factors. The stability of respiratory motion significantly influences the image quality of 2D, free-breathing, black-blood coronary wall MR imaging.

Magnetic resonance coronary angiography: where are we today?

Although cardiovascular magnetic resonance allows the non-invasive and radiation free visualization of both the coronary arteries and veins, coronary vessel wall imaging is still undergoing technical development to improve diagnostic quality. Assessment of the coronary vessels is a valuable addition to the analysis of cardiac function, cardiac anatomy, viability and perfusion which magnetic resonance imaging reliably allows. However, cardiac and respiratory motion and the small size of the coronary vessels present a challenge and require several technical solutions for image optimization. Furthermore, the acquisition protocols need to be adapted to the specific clinical question. This review provides an update on the current clinical applications of cardiovascular magnetic resonance coronary angiography, recent technical advances and describes the acquisition protocols in use.

Coronary imaging with cardiovascular magnetic resonance: current state of the art

Cardiovascular magnetic resonance allows noninvasive and radiation-free visualization of both the coronary arteries and veins, with the advantage of an integrated assessment of cardiac function, viability, perfusion, and anatomy. This combined approach provides valuable integrated information for patients with coronary artery disease and patients undergoing cardiac resynchronization therapy. Moreover, magnetic resonance offers the possibility of coronary vessel wall imaging, therefore assessing the anatomy and pathology of the normal and diseased coronary vessels noninvasively. Coronary magnetic resonance angiography is challenging because of cardiac and respiratory motion and the small size and tortuous path of the coronary vessels. Several technical solutions have been developed to optimize the acquisition protocol to the specific clinical question. The aims of this review are to provide an update on current technical improvements in coronary magnetic resonance angiography, including how to optimize the acquisition protocols, and to give an overview of its current clinical application.

Impact of an abdominal belt on breathing patterns and scan efficiency in whole-heart coronary magnetic resonance angiography: comparison between the UK and Japan

BACKGROUND

Long acquisition times and complex breathing motion patterns lead to suboptimal image quality in whole heart coronary magnetic resonance angiography (WHCMRA). To overcome this problem, an abdominal belt (BELT) has been suggested by a Japanese group. However, its applicability in a Western population has not been previously demonstrated. The purpose of this study was to investigate 1) how the application of a BELT alters breathing patterns during MR scanning and 2) whether the BELT has a similar impact on breathing patterns in UK and Japanese patient populations.

METHODS

30 patients (15 in the UK and 15 in Japan) were studied at 1.5 Tesla (Achieva, Philips Healthcare). Real time navigator positioned through the right diaphragm in cranio-caudal direction was evaluated. Measurements were performed in the supine position with free breathing for one minute before and after a tight-fitting BELT was positioned around the patient's abdomen. End expiratory position (EEP), end inspiratory position (EIP), end expiratory duration (EED) for the right diaphragm and respiratory rate (RR) were obtained. Scan efficiency (SE) was calculated as follows; SE = [the duration within 5 mm gating window per minutes]/[RR interval]/[heart rate].

RESULTS

Height and weight of UK patients were significantly larger than in the Japanese population (171.2 ± 10.8 cm vs 160.8 ± 8.5 cm, p = 0.007; 80.5 ± 22.5 kg vs 59.9 ± 7.7 kg, p = 0.004). After fitting the BELT, EEP-EIP decreased (all patients, 14.9 ± 6.2 mm to 9.4 ± 3.8 mm, p < 0.001; UK patients, 15.9 ± 6.0 mm to 9.7 ± 3.1 mm, p = 0.001; Japanese patients, 14.0 ± 6.4 mm to 9.1 ± 4.6 mm, p = 0.001), RR increased (all patients, 10.0 ± 3.1 min(-1) to 11.2 ± 3.0 min(-1), p = 0.003; UK patients, 9.5 ± 2.8 min(-1) to 10.7 ± 2.8 min(-1), p = 0.038; Japanese patients, 10.4 ± 3.5 min(-1) to 11.8 ± 3.1 min(-1), p = 0.036), and calculated scan efficiency increased (all patients, 45.3 ± 11.4% to 58.6 ± 17.0%, p < 0.001; UK patients, 44.2 ± 10.8% to 55.7 ± 16.7%, p = 0.004; Japanese patients, 46.3 ± 32.2% to 61.0 ± 17.6%, p = 0.001). No significant differences were found between UK and Japanese patients before and after administration of the BELT.

CONCLUSION

Using a BELT significantly increases whole-heart coronary MR angiography scan efficiency in both UK and Japanese patients.

Use of 2D sensitivity encoding for slow-infusion contrast-enhanced isotropic 3-T whole-heart coronary MR angiography

OBJECTIVE

The purpose of this study was to improve the blood-pool signal-to-noise ratio (SNR) and blood-myocardium contrast-to-noise ratio (CNR) of slow-infusion 3-T whole-heart coronary MR angiography (MRA).

SUBJECTS AND METHODS

In 2D sensitivity encoding (SENSE), the number of acquired k-space lines is reduced, allowing less radiofrequency excitation per cardiac cycle and a longer TR. The former can be exploited for signal enhancement with a higher radiofrequency excitation angle, and the latter leads to noise reduction due to lower data-sampling bandwidth. Both effects contribute to SNR gain in coronary MRA when spatial and temporal resolution and acquisition time remain identical. Numeric simulation was performed to select the optimal 2D SENSE pulse sequence parameters and predict the SNR gain. Eleven patients underwent conventional unenhanced and the proposed 2D SENSE contrast-enhanced coronary MRA acquisition. Blood-pool SNR, blood-myocardium CNR, visible vessel length, vessel sharpness, and number of side branches were evaluated.

RESULTS

Consistent with the numeric simulation, using 2D SENSE in contrast-enhanced coronary MRA resulted in significant improvement in aortic blood-pool SNR (unenhanced vs contrast-enhanced, 37.5 ± 14.7 vs 121.3 ± 44.0; p < 0.05) and CNR (14.4 ± 6.9 vs 101.5 ± 40.8; p < 0.05) in the patient sample. A longer length of left anterior descending coronary artery was visualized, but vessel sharpness, coronary artery coverage, and image quality score were not improved with the proposed approach.

CONCLUSION

In combination with contrast administration, 2D SENSE was found effective in improving SNR and CNR in 3-T whole-heart coronary MRA. Further investigation of cardiac motion compensation is necessary to exploit the SNR and CNR advantages and to achieve submillimeter spatial resolution.

Optimization of coronary whole-heart MRA free-breathing technique at 3 Tesla

Four different techniques for 3-T whole-heart coronary magnetic resonance angiography (MRA) using free-breathing three-dimensional segmented parallel imaging and adiabatic T2-preparation were assessed. Coronary MRA at 3 T is improved by shortening the acquisition window more than employing the highest spatial resolution. Double-oblique whole-heart acquisitions result in better overall image quality and allow for better delineation of the left anterior descending coronary artery. It is possible to attain shorter acquisition windows and a smaller voxel size at 3 T than previously reported at 1.5 T.

Whole-heart coronary MR angiography with 2D self-navigated image reconstruction

Several self-navigation techniques have been proposed to improve respiratory motion compensation in coronary MR angiography. In this work, we implemented a 2D self-navigation method by using the startup profiles of a whole-heart balanced Steady-state free precession sequence, which are primarily used to catalyze the magnetization towards the steady-state. To create 2D self-navigation images (2DSN), we added phase encoding gradients to the startup profiles. With this approach we calculated foot-head and left-right motion and performed retrospective translational motion correction. The 2DSN images were reconstructed from 10 startup profiles acquired at the beginning of each shot. Nine healthy subjects were scanned, and the proposed method was compared to a 1D self-navigation (1DSN) method with foot-head correction only. Foot-head correction was also performed with the diaphragmatic 1D pencil beam navigator (1Dnav) using a tracking factor of 0.6. 2DSN shows improved motion correction compared to 1DSN and 1Dnav for all coronary arteries and all subjects for the investigated diaphragmatic gating window of 10 mm. The visualized vessel length of the right coronary artery could be significantly improved with a multiple targeted 2D self-navigation approach, compared to 2DSN method.

A prospective study for comparison of MR and CT imaging for detection of coronary artery stenosis

OBJECTIVES

the purpose of the present study was to directly compare the diagnostic accuracy of magnetic resonance imaging (MRI) and multislice computed tomography (CT) for the detection of coronary artery stenosis.

BACKGROUND

both imaging modalities have emerged as potential noninvasive coronary imaging modalities; however, CT-unlike MRI-exposes patients to radiation and iodinated contrast agent.

METHODS

one hundred twenty consecutive patients with suspected or known coronary artery disease prospectively underwent 32-channel 3.0-T MRI and 64-slice CT before elective X-ray angiography. The diagnostic accuracy of the 2 modalities for detecting significant coronary stenosis (≥ 50% luminal diameter stenosis) in segments ≥ 1.5 mm diameter was compared with quantitative invasive coronary angiography as the reference standard.

RESULTS

in the patient-based analysis MRI and CT angiography showed similar diagnostic accuracy of 83% (95% confidence interval [CI]: 75 to 87) versus 87% (95% CI: 80 to 92), p = 0.38; sensitivity of 87% (95% CI: 76 to 93) versus 90% (95% CI: 80 to 95), p = 0.16; and specificity of 77% (95% CI: 63 to 87) versus 83% (95% CI: 70 to 91), p = 0.06, respectively. All cases of left main or 3-vessel disease were correctly diagnosed by MRI and CT angiography. In the patient-based analysis MRI and CT angiography were similar in their ability to identify patients who subsequently underwent revascularization: the area under the receiver-operator characteristic curve was 0.78 (95% CI: 0.69 to 0.87) for MRI and 0.82 (95% CI: 0.74 to 0.90) for CT angiography.

CONCLUSIONS

thirty-two channel 3.0-T MRI and 64-slice CT angiography similarly identify significant coronary stenosis in patients with suspected or known coronary artery disease scheduled for elective coronary angiography. However, CT angiography showed a favorable trend toward higher diagnostic performance.

Diagnostic accuracy of 1.5-T unenhanced whole-heart coronary MR angiography performed with 32-channel cardiac coils: initial single-center experience

PURPOSE

To compare the imaging time and image quality obtained with whole-heart coronary magnetic resonance (MR) angiography performed with five- and 32-channel coils in healthy subjects and determine the accuracy of MR angiography performed with 32-channel coils in the detection of obstructive coronary artery disease (CAD).

MATERIALS AND METHODS

The institutional review board approved the study protocol, and all participants provided written informed consent. The authors studied 10 healthy subjects and 67 patients suspected of having CAD who were scheduled for coronary angiography. Unenhanced 1.5-T coronary MR angiography was performed with five- and 32-channel coils in healthy subjects and with 32-channel coils in patients. Clinically significant CAD was defined as a diameter reduction of at least 50% at coronary angiography. The sensitivity and specificity of coronary MR angiography were calculated.

RESULTS

The mean imaging time was substantially reduced from 12.3 minutes ± 4.2 (standard deviation) with five-channel coils to 6.3 minutes ± 2.2 with 32-channel coils, with equivalent image quality scores. Acquisition of MR angiograms was completed in all 67 patients, with a mean imaging time of 6.2 minutes ± 2.8. The prevalence of CAD in the study population was 58% (39 of the 67 patients). The areas under the receiver operating characteristic curves as determined at vessel- and patient-based analyses were 0.91 and 0.90, respectively; the sensitivity and specificity at vessel-based analysis were 86% and 93%, respectively.

CONCLUSION

Whole-heart coronary MR angiography performed at 1.5 T with 32-channel coils permits noninvasive detection of CAD with substantially reduced imaging time. This noninvasive approach can be an alternative to multidetector computed tomographic coronary angiography for ruling out obstructive CAD in patients who have a contraindication to contrast material and in young subjects who are at higher risk from ionizing radiation.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101323/-/DC1.

Beat-to-beat respiratory motion correction with near 100% efficiency: a quantitative assessment using high-resolution coronary artery imaging

This study quantitatively assesses the effectiveness of retrospective beat-to-beat respiratory motion correction (B2B-RMC) at near 100% efficiency using high-resolution coronary artery imaging. Three-dimensional (3D) spiral images were obtained in a coronary respiratory motion phantom with B2B-RMC and navigator gating. In vivo, targeted 3D coronary imaging was performed in 10 healthy subjects using B2B-RMC spiral and navigator gated balanced steady-state free-precession (nav-bSSFP) techniques. Vessel diameter and sharpness in proximal and mid arteries were used as a measure of respiratory motion compensation effectiveness and compared between techniques. Phantom acquisitions with B2B-RMC were sharper than those acquired with navigator gating (B2B-RMC vs. navigator gating: 1.01±0.02 mm(-1) vs. 0.86±0.08 mm(-1), P<.05). In vivo B2B-RMC respiratory efficiency was significantly and substantially higher (99.7%±0.5%) than nav-bSSFP (44.0%±8.9%, P<.0001). Proximal and mid vessel sharpnesses were similar (B2B-RMC vs. nav-bSSFP, proximal: 1.00±0.14 mm(-1) vs. 1.08±0.11 mm(-1), mid: 1.01±0.11 mm(-1) vs. 1.05±0.12 mm(-1); both P=not significant [ns]). Mid vessel diameters were not significantly different (2.85±0.39 mm vs. 2.80±0.35 mm, P=ns), but proximal B2B-RMC diameters were slightly higher (2.85±0.38 mm vs. 2.70±0.34 mm, P<.05), possibly due to contrast differences. The respiratory efficiency of B2B-RMC is less variable and significantly higher than navigator gating. Phantom and in vivo vessel sharpness and diameter values suggest that respiratory motion compensation is equally effective.

Assessment of coronary artery disease using magnetic resonance coronary angiography: a national multicenter trial

OBJECTIVES

This national multicenter study determined the diagnostic performance of 1.5-T whole-heart coronary magnetic resonance angiography (MRA) in patients with suspected coronary artery disease (CAD).

BACKGROUND

Whole-heart coronary MRA using steady-state free precession allows noninvasive detection of CAD without the administration of contrast medium. However, the accuracy of this approach has not been determined in a multicenter trial.

METHODS

Using a 1.5-T magnetic resonance imaging unit, free-breathing steady-state free precession whole-heart coronary MRA images were acquired for 138 patients with suspected CAD at 7 hospitals. The accuracy of MRA for detecting a ≥ 50% reduction in diameter was determined using X-ray coronary angiography as the reference method.

RESULTS

Acquisition of whole-heart coronary MRA images was performed in 127 (92%) of 138 patients with an average imaging time of 9.5 ± 3.5 min. The areas under the receiver-operator characteristic curve from MRA images according to vessel- and patient-based analyses were 0.91 (95% confidence interval [CI]: 0.87 to 0.95) and 0.87 (95% CI: 0.81 to 0.93), respectively. The sensitivity, specificity, positive and negative predictive values, and accuracy of MRA according to a patient-based analysis were 88% (49 of 56, 95% CI: 75% to 94%), 72% (51 of 71, 95% CI: 60% to 82%), 71% (49 of 69, 95% CI: 59% to 81%), 88% (51 of 58, 95% CI: 76% to 95%), and 79% (100 of 127, 95% CI: 72% to 86%), respectively.

CONCLUSIONS

Non-contrast-enhanced whole-heart coronary MRA at 1.5-T can noninvasively detect significant CAD with high sensitivity and moderate specificity. A negative predictive value of 88% indicates that whole-heart coronary MRA can rule out CAD.

[Cardiac functional analysis with MRI]

Cardiovascular diseases (CVD) are among the leading causes of death worldwide. Even in the 21(st) century CVD will still be the most frequent cause of morbidity and mortality. Precise evaluation of cardiac function is therefore mandatory for therapy planning and monitoring. In this article the contribution of MRI-based analysis of cardiac function will be addressed. Nowadays cine-MRI is considered as the standard of reference (SOR) in cardiac functional analysis. ECG-triggered steady-state free precession (SSFP) sequences are mainly used as they stand out due to short acquisition times and excellent contrast between the myocardium and the ventricular cavity. An indispensible requirement for cardiac functional analysis is an exact planning of the examination and based on that the coverage of the whole ventricle in short axial slices. By means of dedicated post-processing software, manual or semi-automatic segmentation of the endocardial and epicardial contours is necessary for functional analysis. In this way end-diastolic volume (EDV), end-systolic volume (ESV) and the ejection fraction (EF) are defined and regional wall motion abnormalities (RWMA) can be detected.

The effect of dynamic vessel motion on haemodynamic parameters in the right coronary artery: a combined MR and CFD study

Human right coronary artery (RCA) haemodynamics is investigated using computational fluid dynamics (CFD) based on subject-specific information from magnetic resonance (MR) acquisitions. The dynamically varying vascular geometry is reconstructed from MR images, incorporated in CFD in conjunction with pulsatile flow conditions obtained from MR velocity mapping performed on the same subject. The effects of dynamic vessel motion on instantaneous and cycle-averaged haemodynamic parameters, such as wall shear stress (WSS), time-averaged WSS (TAWSS) and oscillatory shear index (OSI), are examined by comparing an RCA model with a time-varying geometry and those with a static geometry, corresponding to nine different time-points in the cardiac cycle. The results show that the TAWSS is similar for the dynamic and static wall models, both qualitatively and quantitatively (correlation coefficient 0.89-0.95). Conversely, the OSI shows much poorer correlations (correlation coefficient 0.38-0.60), with the best correspondence being observed with the static models constructed from images acquired in late diastole (at t = 0 and 800 ms, the cardiac cycle is 900 ms). These findings suggest that neglecting dynamic motion of the RCA is acceptable if TAWSS is the primary focus but may result in underestimation of haemodynamic parameters related to the oscillatory nature of the blood flow.

MR image-based geometric and hemodynamic investigation of the right coronary artery with dynamic vessel motion

The aim of this study was to develop a fully subject-specific model of the right coronary artery (RCA), including dynamic vessel motion, for computational analysis to assess the effects of cardiac-induced motion on hemodynamics and resulting wall shear stress (WSS). Vascular geometries were acquired in the right coronary artery (RCA) of a healthy volunteer using a navigator-gated interleaved spiral sequence at 14 time points during the cardiac cycle. A high temporal resolution velocity waveform was also acquired in the proximal region. Cardiac-induced dynamic vessel motion was calculated by interpolating the geometries with an active contour model and a computational fluid dynamic (CFD) simulation with fully subject-specific information was carried out using this model. The results showed the expected variation of vessel radius and curvature throughout the cardiac cycle, and also revealed that dynamic motion of the right coronary artery consequent to cardiac motion had significant effects on instantaneous WSS and oscillatory shear index. Subject-specific MRI-based CFD is feasible and, if scan duration could be shortened, this method may have potential as a non-invasive tool to investigate the physiological and pathological role of hemodynamics in human coronary arteries.

[MR imaging of coronary arteries: noncontrast free-breathing whole heart acquisition with ultrafast 3D balanced gradient-echo technique]

The 3D balanced gradient-echo technique is described along with th eimaging protocol for MR imaging of th ecoronary arteries. A 3D volume with spatial resolution of 0.6 x 0.6 x 0.75 mm composed of 140 slices covering the whole heart is acquired over 10 minutes. The main advantage of this whole heart technique is the possibility to image the coronary arteries along their entire course in a single acquisition. Selection of the navigator positions, timing of image acquisition and its duration through the R-R interval are the main factors requiring optimization.