Imaging of pediatric great vessel stents: Computed tomography or magnetic resonance imaging?

__Background:__ Complications might occur after great vessel stent implantation in children. Therefore follow- up using imaging is warranted. __Purpose:__ To determine the optimal imaging modality for the assessment of stents used to treat great vessel obstructions in children. __Material and methods:__ Five different large vessel stents were evaluated in an in-vitro setting. All stents were expanded to the maximal vendor recommended diameter (20mm; n = 4 or 10mm; n = 1), placed in an anthropomorphic chest phantom and imaged with a 256-slice CT-scanner. MRI images were acquired at 1.5T using a multi-slice T2-weighted turbo spin echo, an RFspoiled three-dimensional T1-weighted Fast Field Echo and a balanced turbo field echo 3D seq

New dimensions in cardiovascular CT

Recent developments in CT hardware and software technique might allow for functional analysis of CAD. The aim of this thesis was to evaluate the diagnostic performance of both anatomical and functional analysis on CT for the evaluation of CAD. As the interest in CT as a tool for the evaluation of cardiovascular disease is increasing, the secondary aim of this thesis was to reduce the drawbacks of CT. Major drawback of CT are the use of ionizing radiation dose and the need for injection of iodinated contrast media. Typically, a cardiac CT investigation for CAD evaluation comprises a non-contrast cardiac CT scan followed by a contrast enhanced coronary CT scan (CCTA). Quantification of atherosclerotic calcifications is performed on the non-contrast CT to identify patients at risk for adverse cardiovascular events. In this thesis we showed that these calcifications can be quantified on CT scans acquired at reduced radiation dose. We found that iterative reconstruction, an alternative method to reconstruct acquired images, allowed for even further dose reduction. The contrast enhanced coronary CT scan is performed to evaluate CAD in the coronary lumen. Results of our phantom studies showed that with the use of dual-energy CT (DECT), iodinated contrast media concentrations can be reduced without loss of objective image quality. And that gadolinium can be used as an alternative contrast agent for DECT acquisitions. In this thesis we showed that DECT allows for accurate iodine quantification. Because iodine quantification in the myocardium is a surrogate for myocardial perfusion, this opens up the possibilities for functional analysis of CAD. In additional patients studies we showed that CT software techniques (namely CCTA-derived fractional flow reserve and deep learning) allowed for functional analysis of CAD and increased the diagnostic performance of CT. A clinical study in which these CT hardware and software techniques are combined to improve the specificity of CT was proposed, and is currently ongoing. A combined evaluation of both anatomical and functional analysis improves the diagnostic performance of CT for the diagnosis of functionally significant CAD. The ongoing clinical study will clarify to what extent the diagnostic performance of CT can be improved. Additionally, iterative reconstruction and DECT can be used to reduce major drawbacks of CT. With an improved diagnostic performance and reduction of drawbacks, CT might become an even more important tool for the detection, visualization and evaluation of cardiovascular disease

Circulating Concentrations of Soluble Interleukin 6 Receptors gp80 an gp130 in Chronic Renal Failure and Effects of Renal Replacement Therapy

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Anterior longitudinal ligament in diffuse idiopathic skeletal hyperostosis: Ossified or displaced?

Diffuse idiopathic skeletal hyperostosis (DISH) is often theorized to be an ossification of the anterior longitudinal ligament (ALL). Using computed tomography (CT) imaging and cryomacrotome sectioning, we investigated the spatial relationship between the ALL and newly formed bone in DISH to test this hypothesis. In the current study, four human cadaveric spines diagnosed with DISH using CT imaging were frozen and sectioned using a cryomacrotome. Photographs were obtained of the specimen at 125 µm intervals. Manual segmentations of the ALL on cryomacrotome photographs were projected onto the three-dimensional reconstructed CT scans. The presence and location of newly formed bone were assessed in relationship to the location of the ALL. The ALL could be identified and segmented on the photographs at all levels. The ALL was located at the midline at levels where no new bone had formed. At the locations where new bone had abundantly formed, the ALL was displaced towards to the contralateral side and not replaced by bony tissue. The displacement of the—morphologically normal appearing—ALL away from the newly formed bone implies that newly formed bone in DISH may not originate from the ALL.Biomaterials & Tissue Biomechanic