Improvement of image quality of non-invasive coronary artery imaging with magnetic resonance by the use of the intravascular contrast agent Clariscan (NC100150 injection) in patients with coronary artery disease

Nanotechnology in coronary heart disease

Coronary heart disease (CHD) is one of the major causes of death and disability worldwide, especially in low- and middle-income countries and among older populations. Conventional diagnostic and therapeutic approaches have limitations such as low sensitivity, high cost and side effects. Nanotechnology offers promising alternative strategies for the diagnosis and treatment of CHD by exploiting the unique properties of nanomaterials. In this review, we use bibliometric analysis to identify research hotspots in the application of nanotechnology in CHD and provide a comprehensive overview of the current state of the art. Nanomaterials with enhanced imaging and biosensing capabilities can improve the early detection of CHD through advanced contrast agents and high-resolution imaging techniques. Moreover, nanomaterials can facilitate targeted drug delivery, tissue engineering and modulation of inflammation and oxidative stress, thus addressing multiple aspects of CHD pathophysiology. We discuss the application of nanotechnology in CHD diagnosis (imaging and sensors) and treatment (regulation of macrophages, cardiac repair, anti-oxidative stress), and provide insights into future research directions and clinical translation. This review serves as a valuable resource for researchers and clinicians seeking to harness the potential of nanotechnology in the management of CHD. STATEMENT OF SIGNIFICANCE: Coronary heart disease (CHD) is the one of leading cause of death and disability worldwide. Nanotechnology offers new strategies for diagnosing and treating CHD by exploiting the unique properties of nanomaterials. This review uses bibliometric analysis to uncover research trends in the use of nanotechnology for CHD. We discuss the potential of nanomaterials for early CHD detection through advanced imaging and biosensing, targeted drug delivery, tissue engineering, and modulation of inflammation and oxidative stress. We also offer insights into future research directions and potential clinical applications. This work aims to guide researchers and clinicians in leveraging nanotechnology to improve CHD patient outcomes and quality of life.

Iron oxide nanoparticles: Diagnostic, therapeutic and theranostic applications

Many different iron oxide nanoparticles have been evaluated over the years, for a wide variety of biomedical applications. We here summarize the synthesis, surface functionalization and characterization of iron oxide nanoparticles, as well as their (pre-) clinical use in diagnostic, therapeutic and theranostic settings. Diagnostic applications include liver, lymph node, inflammation and vascular imaging, employing mostly magnetic resonance imaging but recently also magnetic particle imaging. Therapeutic applications encompass iron supplementation in anemia and advanced cancer treatments, such as modulation of macrophage polarization, magnetic fluid hyperthermia and magnetic drug targeting. Because of their properties, iron oxide nanoparticles are particularly useful for theranostic purposes. Examples of such setups, in which diagnosis and therapy are intimately combined and in which iron oxide nanoparticles are used, are image-guided drug delivery, image-guided and microbubble-mediated opening of the blood-brain barrier, and theranostic tissue engineering. Together, these directions highlight the versatility and the broad applicability of iron oxide nanoparticles, and indicate the integration in future medical practice of multiple iron oxide nanoparticle-based materials.

Determination of blood circulation times of superparamagnetic iron oxide nanoparticles by T2* relaxometry using ultrashort echo time (UTE) MRI

Blood circulation is an important determinant of the biodistribution of superparamagnetic iron oxide nanoparticles. Here we present a magnetic resonance imaging (MRI) technique based on the use of ultrafast echo times (UTE) for the noninvasive determination of blood half-lives at high particle concentrations, when conventional pulse sequences fail to produce a useful MR signal. Four differently coated iron oxide nanoparticles were administered intravenously at a dose of 500 μmol Fe/kg bodyweight and UTE images of C57BL/6 mice were acquired on a 1-T ICON scanner (Bruker). T2* relaxometry was done by acquiring UTE images with echo times of 0.1, 0.8 and 1.6 ms. Blood circulation time was then determined by fitting an exponential curve to the time course of the measured relaxation rates. Circulation time was shortest for particles coated with malic acid (t1/2=23 min) and longest for particles coated with tartaric acid (t1/2=63 min). UTE-based T2* relaxometry allows noninvasive determination of blood circulation time and is especially useful when high particle concentrations are present.

Visualization of chronic myocardial infarction using the intravascular contrast agent MS-325 (gadofosveset) in patients

Aims. The aim of this study was to evaluate the potential of visualizing chronic myocardial infarction in patients using the intravascular CA MS-325 (gadofosveset, EPIX Pharmaceuticals, Mass, USA). Methods. Nine patients were enrolled in a clinical phase II multicenter trial for MRCA and perfusion imaging using MS-325. They had objective evidence of chronic myocardial infarction as visualized by previously performed late gadolinium (Gd) enhancement imaging (LGE) with a conventional extracellular Gd-DTPA CA (Magnevist, Bayer Healthcare, Germany, 0.2 mmol/kg/body weight) serving as reference standard. A prepulse-optimized LGE study was performed immediately and at several time points after injection of MS-325 (0.05 mmol/kg/body weight). The number and localization of segments demonstrating LGE with MS-325 as well as signal intensities were compared with the reference standard (Gd-DTPA). Results. Using MS-325, LGE could be detected at every time point in all 9 patients. The accuracy of LGE with MS-325 as compared to LGE with Gd-DTPA was highest 54 ± 4 minutes after contrast injection, resulting in a sensitivity of 84% with a specificity of 98%. Conclusion. The intravascular CA MS-325 has the potential to visualize chronic myocardial infarction. However, in comparison with Gd-DTPA, the transmural extent and the number of segments are smaller.

Layer-by-layer capsules for magnetic resonance imaging and drug delivery

Layer-by-layer (LbL) self-assembled polyelectrolyte capsules have demonstrated their unique advantages and capability in drug delivery applications. These ordered micro/nano-structures are also promising candidates as imaging contrast agents for diagnostic and theranostic applications. Magnetic resonance imaging (MRI), one of the most powerful clinical imaging modalities, is moving forward to the molecular imaging field and requires the availability of advanced imaging probes. In this review, we are focusing on the design of MRI visible LbL capsules, which incorporate either paramagnetic metal-ligand complexes or superparamagnetic iron oxide (SPIO) nanoparticles. The design criteria cover the topics of probe sensitivity, biosafety, long-circulation property, targeting ligand decoration, and drug loading strategies. Examples of MRI visible LbL capsules with paramagnetic or superparamagnetic moieties were given and discussed. This carrier platform can also be chosen for other imaging modalities.

Coronary MR angiography using citrate-coated very small superparamagnetic iron oxide particles as blood-pool contrast agent: initial experience in humans

PURPOSE

To evaluate very small superparamagnetic iron oxide particles (VSOP-C184) as blood-pool contrast agent for coronary MR angiography (CMRA) in humans.

MATERIALS AND METHODS

Six healthy volunteers and 14 patients with suspected coronary artery disease underwent CMRA after administration of VSOP-C184 at the following doses: 20 μmol Fe/kg (4 patients), 40 μmol Fe/kg (5 patients), 45 μmol Fe/kg (6 healthy volunteers), and 60 μmol Fe/kg (5 patients). In healthy volunteers, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and vessel edge definition (VED) of contrast-enhanced CMRA were compared with non-contrast-enhanced CMRA. In patients, a per-segment intention-to-diagnose evaluation of contrast-enhanced CMRA for detection of significant coronary stenosis (≥50%) was performed.

RESULTS

Three healthy volunteers (45 μmol Fe/kg VSOP-C184) and two patients (60 μmol Fe/kg VSOP-C184) had adverse events of mild or moderate intensity. VSOP-C184 significantly increased CNR (15.1 ± 4.6 versus 6.9 ± 1.9; P = 0.010), SNR (21.7 ± 5.3 versus 15.4 ± 1.6; P = 0.048), and VED (2.3 ± 0.6 versus 1.2 ± 0.2; P < 0.001) compared with non-contrast-enhanced CMRA. In patients, contrast-enhanced CMRA yielded sensitivity, specificity, and diagnostic accuracy for detection of significant coronary stenosis of 86.7%, 71.0%, 73.1%, respectively.

CONCLUSION

CMRA using VSOP-C184 was feasible and yielded moderate diagnostic accuracy for detection of significant coronary stenosis within this proof-of-concept setting.

Combined magnetic resonance coronary artery imaging, myocardial perfusion and late gadolinium enhancement in patients with suspected coronary artery disease

BACKGROUND

Cardiovascular magnetic resonance (CMR) imaging offers methods for the detection of ischemia and myocardial infarction as well as visualization of the coronary arteries (MRCA). However, a direct comparison of adenosine perfusion (PERF), late gadolinium enhancement (LGE) and MRCA or the results of their combination has not been performed. Aim of the study was to evaluate the feasibility/diagnostic performance of rest/stress perfusion, late gadolinium enhancement and MRCA and their combination in patients with suspected coronary artery disease (CAD) in comparison to invasive angiography.

METHODS

Fifty-four patients (60 +/- 10 years, 35 men, CAD 48%) underwent CMR including MRCA (steady state free precession, navigator whole heart approach, spatial resolution 0.7 x 0.7 x .0.9 mm, trigger delay and temporal resolution adjusted individually), stress PERF (adenosine 140 mug/min/kg), rest PERF (SSFP, 3 short axis, 1 saturation prepulse per slice) and LGE (3D inversion recovery technique) using Gd-BOPTA. Images were analyzed visually. Stenosis >50% in invasive angiography was considered significant.

RESULTS

Mean study time was 68 +/- 11 minutes. Sensitivity for PERF, LGE, MRCA and the combination of PERF/LGE and PERF/LGE/MRCA was 87%, 50%, 91%, 88% and 92%, respectively and specificity 88%, 96%, 46%, 88% and 56%, respectively. If image quality of MRCA was excellent (n = 18) the combination of MRCA/PERF/LGE yield a sensitivity of 86% and specificity of 91%. However, no test or combination improved diagnostic performance significantly compared to PERF alone.

CONCLUSION

In patients with CAD, the combination of stress PERF, LGE and MRCA is feasible. When compared to invasive angiography, adenosine stress perfusion outperforms CMR coronary angiography in direct comparison and yields the best results with non-significant improvement in combination with LGE and significant deterioration in combination with MRCA. MRCA may be of additional value only in a minority of patients with excellent image quality.

Noninvasive detection of coronary artery disease -- challenges for prevention of disease and clinical events

Atherosclerosis is a chronic inflammatory disease that affects essentially all arterial beds including the aorta, coronaries, carotids, and peripheral arteries. It is the main cause of death in the western hemisphere, due to cardiovascular syndromes such as myocardial infarction, heart failure, and cerebrovascular accidents. Very substantial economic and human resources have been used on treatments of its complications, including imaging studies, coronary bypass surgery, catheter interventions, pacemakers, and medical treatments. Treating complications, however, are remedial actions. A better alternative is to prevent the development of atherosclerosis, or at least to identify patients who are at risk of acute events and intervene before they occur. The aims of this review are to discuss the predictive value of traditional and emerging risk factors, as well as the role of noninvasive diagnostic methods for coronary atherosclerosis, including exercise stress test, echo stress test, duplex ultrasound, computed tomography, and magnetic resonance. A combination of serum biomarkers and noninvasive approaches is of practical utility for identifying early disease. It is to be expected that future developments will soon perfect our ability to identify the vulnerable patient and allow a more individualized approach.

Spiral coronary angiography using a blood pool agent

PURPOSE

To experimentally investigate the optimum dose of an iron-oxide-based blood pool agent for spiral coronary MR angiography (MRA), and the difference between single and multiple spiral excitations in each cardiac cycle.

MATERIALS AND METHODS

Images using single and triple spiral excitations in each cardiac cycle were obtained in late diastole of the left main coronary artery in eight pigs following an inversion prepulse. Measurements were obtained before and after injection of increasing doses of an iron oxide blood pool agent (Clariscan) corresponding to concentrations of 0.8, 2.2, and 3.9 mg Fe/kg BW. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured.

RESULTS

For 0.8 mg Fe/kg BW relative to precontrast values, a significant increase was observed for both one (SNR: 2.3, CNR: 3.8) and three (SNR: 1.4, CNR: 2.2) excitations (P < 0.01). When the dose was increased from 0.8 mg Fe/kg BW to 2.2 mg Fe/kg BW, only the SNR (P < 0.01) increased further. Significantly higher CNR (1.6-1.8) and SNR (1.4-1.6) values were seen for one excitation relative to three excitations at all concentrations (P < 0.05).

CONCLUSION

At low concentrations, an iron oxide blood pool agent can increase SNR and CNR significantly with both single excitation and triple excitations using an inversion-prepared spiral acquisition scheme. At higher concentrations, T2* effects reduce image quality.

Diagnostic performance of coronary magnetic resonance angiography as compared against conventional X-ray angiography: a meta-analysis

OBJECTIVES

This study was designed to define the current role of coronary magnetic resonance angiography (CMRA) for the diagnosis of coronary artery disease (CAD).

BACKGROUND

Coronary magnetic resonance angiography has been proposed as a promising noninvasive method for diagnosis of CAD, but individual studies evaluating its clinical value have been of limited sample size.

METHODS

We identified all studies (MEDLINE and EMBASE) that evaluated CAD by both CMRA and conventional angiography in >/=10 subjects during the period 1991 to January 2004. We recorded true and false positive and true and false negative CMRA assessments for detection of CAD using X-ray angiography as the reference standard. Analysis was done at segment, vessel, and subject level.

RESULTS

We analyzed 39 studies (41 separate comparisons). Across 25 studies (27 comparisons) with data on 4,620 segments (993 subjects), sensitivity and specificity for detection of CAD were 73% and 86%, respectively. Vessel-level analyses (16 studies, 2,041 vessels) showed sensitivity 75% and specificity 85%. Subject-level analyses (13 studies, 607 subjects) showed sensitivity 88% and specificity 56%. At the segment level, sensitivity was 69% to 79% for all but the left circumflex (61%) coronary artery; specificity was 82% to 91%. There was considerable between-study heterogeneity, but weighted summary receiver-operating characteristic curves agreed with these estimates. There were no major differences between subgroups based on technical or population characteristics, year of publication, reported blinding, or sample size.

CONCLUSIONS

In evaluable segments of the native coronary arteries, CMRA has moderately high sensitivity for detecting significant proximal stenoses and may have value for exclusion of significant multivessel CAD in selected subjects considered for diagnostic catheterization.

Noninvasive evaluation of coronary artery disease: magnetic resonance imaging & multi-slice computed tomography

Coronary artery disease is the leading cause of death in industrialized countries. Moreover, the disease is reaching endemic proportions and will put an enormous strain on healthcare economics in the near future. Accurate noninvasive diagnosis and functional evaluation of coronary artery disease in early stages is important for selecting the appropriate management strategy in patients with known or suspected coronary artery disease. During the past decade, magnetic resonance imaging and multi-slice computed tomography have emerged as modalities that allow both functional and anatomical imaging of coronary artery disease. Implementation of these modalities may improve the clinical diagnostic workup, prognostification and clinical management of patients with known or suspected coronary artery disease.

The utility of superparamagnetic contrast agents in MRI: theoretical consideration and applications in the cardiovascular system

This review will discuss the in vivo physical chemical relaxation properties of superparamagnetic iron oxide particles. Various parameters such as size, magnetization, compartmentalization and water exchange effects and how these alter the behavior of the iron oxide particles in an in vitro vs an in vivo situation with special reference to the cardiovascular system will be exemplified. Furthermore, applications using iron oxide particles for vascular, perfusion and viability imaging as well as assessment of the inflammatory status of a given tissue will be discussed.

Recurrent coronary artery stenosis: Assessment with three-dimensional MR imaging

PURPOSE

To assess the diagnostic value of three-dimensional coronary magnetic resonance (MR) angiography with fat saturation and navigator echo in the setting of restenosis after percutaneous transluminal coronary angioplasty (PTCA).

MATERIALS AND METHODS

Thirty consecutive patients who had PTCA and were referred for elective coronary reangiography underwent MR imaging and coronary angiography. The pulse sequence was a cardiac triggered, single-slab, three-dimensional, gradient-echo sequence, employing a spin-echo navigator echo measurement to track the variation of the diaphragm during the scan. The following segments of the coronary arteries were included in this prospective study: left main coronary artery, proximal and middle left anterior descending, proximal and middle left circumflex, proximal and middle right coronary artery, and intermediate branch, if present. The quality of the MR images was graded from 0 to 5.

RESULTS

In total, 221 coronary artery segments could be identified. Mean image quality was 3.3. Overall accuracy for segments with an image quality of grade 2 or more was 90%. To achieve a positive predictive value >70% for a significant stenosis/restenosis, only segments with quality >/=3 could be assessed, whereas an acceptable negative predictive value could be achieved for nearly all segments.

CONCLUSION

Our preliminary data suggest that MR coronary angiography may be most helpful as a screening test in selected patients to exclude clinically relevant stenoses or to assess restenoses after PTCA or in patients in whose coronary angiography is relatively contraindicated.

Quantitative parameters of image quality in multidetector spiral computed tomographic coronary imaging with submillimeter collimation

Multidetector computed tomography (MDCT) permits visualization of the coronary arteries, but limited spatial and temporal resolution can lead to artifacts. We quantitatively evaluated the image quality that can be obtained with the latest generation of MDCT scanners with submillimeter collimation and increased gantry rotation speed. Thirty patients with angiographically proved absence of significant coronary artery stenoses (mean age 56 +/- 13 years, mean heart rate 62 +/- 13 beats/min) were studied by MDCT (12 x 0.75 mm collimation, 420-ms tube rotation, 210-ms temporal resolution, 500 mA, 120 kVp, retrospective electrocardiographic gating). In multiplanar reconstructions of the 4 major coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery), the overall visualized vessel length and the length of segments without motion artifacts were measured. Vessel diameters at 8 predefined locations were measured in MDCT maximum intensity projections and in corresponding invasive angiograms. The mean lengths of visualized coronary arteries were left main 13 +/- 6 mm, left anterior descending 138 +/- 39 mm, left circumflex 84 +/- 34 mm, and right coronary artery 155 +/- 41 mm. On average, 93 +/- 13% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 93 +/- 12%, left circumflex 91 +/- 17%, and right coronary artery 87 +/- 14%). The percentage of vessel length visualized free of motion artifacts was significantly higher in patients with a heart rate </=60 beats/min compared with patients with a heart rate >60 beats/min (96 +/- 8% vs 89 +/- 17%, p <0.05). Vessel diameters in MDCT correlated closely to quantitative coronary angiography (R(2) 0.83 to 0.87). In conclusion, MDCT with submillimeter collimation and improved temporal resolution permits reliable visualization of the vessel lumen and accurate measurements of vessel dimensions.