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Preclinical evaluation of multimodality probes
Published in Yi-Hwa Liu, Albert J. Sinusas, Hybrid Imaging in Cardiovascular Medicine, 2017
Radiographic iodinated contrast agents are perhaps the most commonly prescribed drugs in the history of modern medicine (Singh and Daftary 2008). Intravenously delivered iodinated contrast has been utilized extensively in x-ray-based imaging, including x-ray fluoroscopy and CT, to visualize vascular structures like the arteries and veins (e.g., CT angiography) in the heart and periphery. The recent development of iodinated nanoparticles, N1177, has made it feasible to identify ruptured vs. nonruptured atherosclerotic plaques in rabbits (Van Herck et al. 2010). New probes, such as PEGylated, low-generation dendrimer-entrapped gold nanoparticles, have recently emerged and have been tested for cardiovascular imaging (Liu et al. 2014). X-ray probes together with x-ray imaging modalities provide high spatial resolution and allow real-time interactivity. However, most x-ray probes are highly toxic when used intracellularly even at low concentrations, making them unsuitable for cardiac cell labeling and tracking. In addition, the lack of soft tissue visualization and concern about ionizing radiation also limit their cardiac application. However, iodinated contrast agents for vascular imaging are suitable for anatomical visualization in combination with radionuclide probes for molecular imaging.
Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
For suspected subarachnoid haemorrhage CT should be performed ideally within 6 hours of onset of symptoms [24], during which period the sensitivity for detection approaches 100%, although it remains high for 2–3 days. After that sensitivity decreases progressively and post 5–7 days lumbar puncture will often be required for diagnosis (by demonstrating xanthochromia in the CSF). MRI is able to detect subarachnoid haemorrhage but in the acute phase CT is usually easier to perform; it may have a role if imaging is delayed [25], and thus reduce the need for the unpleasant lumbar puncture. CT angiography may also be used to detect the underlying aneurysm if present.
Cardiovascular Imaging for Early Detection of Coronary Artery Disease
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Giorgos Papanastasiou, George Markousis-Mavrogenis, Sophie I. Mavrogeni
In cardiac CT angiography imaging, the high radiation doses involved have raised serious concerns in literature, as the risks of radiation-induced malignancy are not negligible [63, 64], particularly when repetitive scans are needed to assess disease progression or response to therapy. Methods to minimize the radiation dose in cardiac CT angiography protocols have been proposed, such as using prospective ECG-triggering, with which it is possible to image only specific parts of the cardiac cycle [63, 64].
The effect of hemodynamic parameters in patient-based coronary artery models with serial stenoses: normal and hypertension cases
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
K. E. Hoque, M. Ferdows, S. Sawall, E. E. Tzirtzilakis
Coronary CT angiography was performed on a dual-source CT (DSCT) scanner (SOMATOM Force, Siemens Healthineers, Germany). The scanning parameters were as follows: (i) tube voltage 100 kV, (ii) tube current 450 mAs. Detector collimation 0.75 × 192 × 0.6 mm. Time per gantry revolution 0.25 ms resulting in a temporal resolution of 66 ms. The CTA was performed using prospective ECG-gating. A bolus tracking technique was used for CTA scans and the triggering threshold was set to a CT-value of 100–140 HU in the ascending aorta. The scan was obtained with intravenous injection of 40–60 ml IOHEXOL (350 mg I/mL, IOPAMEDOL 350) at a flow rate of 4–5 ml/s followed by 30 ml saline chaser at the same flow rate. The CTA scan was acquired from 2 cm below the level of the tracheal bifurcation to 1–2 cm below the level of the diaphragm. Image data were routinely automatically reconstructed in best diastolic and best systolic position in the R-R interval with a slice thickness of 0.75 mm, slice increment of 0.75 mm and a medium to smooth convolution kernel B26f. The Field of view (FOV) was 170 mm with a matrix size 256 × 256.
The role of cardiac computed tomography in pre-participation screening of mature athletes
Published in European Journal of Sport Science, 2022
Georgios A. Christou, Asterios P. Deligiannis, Evangelia J. Kouidi
Protocols of coronary CT angiography usually involve an initial non-contrast phase with low radiation for measurement of CACS. Coronary CT angiography is not recommended to be performed in the presence of extensive coronary calcification, which may decrease image quality due to blooming artefacts (Leipsic et al., 2014). Specifically, coronary CT angiography is considered an appropriate investigation only for individuals with CACS ≤ 400 (Taylor et al., 2010). In case of CACS>400, invasive coronary angiography is recommended. Repeat coronary CT angiography in asymptomatic individuals with prior test results is considered inappropriate (Taylor et al., 2010).
Patient-specific, multiscale, myocardial blood flow simulation for coronary artery disease
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
L. Papamanolis, H. J. Kim, C. Jaquet, M. Sinclair, M. Schaap, I. Danad, P. van Diemen, P. Knaapen, L. Najman, H. Talbot, C. A. Taylor, I. E. Vignon-Clementel
The aorta, coronary arteries and left ventricle (LV) are segmented from Coronary CT Angiography (CCTA). The segmented arteries are coupled to a synthetic arterial network (Jaquet et al. 2019). An aortic root pressure of 93 mmHg drives flow into the model, which is terminated either by terminal resistances (coronary model) or is connected to a myocardium model (coupled model). For parameter tuning, the target flowrate is based on the patient LV mass, except for the obstructive CAD patient for which it comes from PET data as LV mass-based flow is too high.