View clinical trials related to Magnetic Resonance Angiography.
Filter by:This study is aimed to assess the value of three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) in hemodialysis patients with occlusive disease in arteriovenous fistula (AVF). All participants will receive 3D-TOF-MRA and ultrasound to detect the stenosis degree of AVF.
this study discussed the pathogenesis, treatment, and prognosis of severe cerebral infarction and ophthalmic artery occlusion for Aisan induced by hyalruonic acid filler injection.
Magnetic resonance coronary angiography (MRCA) has its advantage in its ability to assess the coronary artery morphology without radiation or contrast media. The clinical application of MRCA is still challenging mainly because of technical limitations such as: its time-consuming image acquisition, inconsistent image quality, and low spatial resolution. Optimization of MRCA image acquisition method is in progress and compressed sensing (CS) with post-processing (de-noising) by deep learning reconstruction (DLR) is promising to solve these problems. The lack of a consensus method to assess the coronary stenosis on MRCA is another issue. Generally, a stenosis in MRCA is observed as a signal intensity (SI) drop along the artery compared to the healthy segments. A previous study has reported from its comparison of MRCA with coronary angiography (CAG) that the SI drop of 35% in MRCA stenosis lesion corresponded to the significant stenosis in CAG. Although this SI drop phenomenon was not observed in a different study on chronic total obstruction cases. One of the hypothesized reasons is that the SI drop in MRCA is affected not only by the stenosis severity but also the plaque characteristics, which is not assessable by CAG. To investigate this hypothesis coronary CTA is needed, which is a robust modality to assess coronary stenosis and plaque characteristics. Comparison between MRCA with CTA has the potential to give better information for developing a robust method to assess MRCA. In this study, the investigators aim to evaluate the feasibility of MRCA scanned with optimized protocol and post-processing, and to develop robust coronary artery assessment method on MRCA, by comparison with clinical coronary CTA.
This study aims to evaluate whether quantitative analysis of coronary MR angiogram would improve the detection of functionally-significant coronary artery stenosis.
Conventional vascular imaging techniques are often either contra-indicated in chronic kidney disease (CKD) patients due to their relative invasiveness, risks and cost. Computed tomography angiography (CTA) requires radiation and nephrotoxic iodinated contrast which may precipitate significant worsening of renal function and even prompt the need for institution of dialysis. Magnetic resonance angiography (MRA) using gadolinium-based contrast agents has been associated with the rare disease nephrogenic systemic fibrosis. Alternative imaging methods also have drawbacks: for example, this frail patient group has a higher risk of complications from conventional invasive catheter-based angiography, non-contrast-enhanced MRA allows visualization of smaller arteries but is less accurate for larger vascular structures, and ultrasound is often not appropriate for evaluation of the deep vessels of the abdomen and pelvis. Ferumoxytol is an ultrasmall superparamagnetic iron oxide particle encapsulated by a semisynthetic carbohydrate, which was initially developed as a magnetic resonance imaging (MRI) contrast agent in 2000. However, interest in ferumoxytol as a therapeutic agent for the treatment of iron deficiency anaemia in the setting of CKD eclipsed its use as MRI contrast agent. During the last decade, ferumoxytol has gained appeal as an MRI contrast agent in patients with estimated glomerular filtration rates <30mL/min and there are reports in the literature for its safe use and utility in both adult and pediatric patients with CKD. Participants will be selected from those who have been referred for assessment prior to kidney transplant or prior to vascular access creation for haemodialysis and will be divided into three groups. The first group will include patients who will undergo a CTA of abdominal and aortoiliac vasculature as part of their preparation for potential kidney transplantation. The second and third groups will include patients who are having a fistula or a graft created for dialysis, respectively. These patients are routinely having US vascular mapping to visualise the blood vessels before a fistula or a graft is created. Additionally, patients included in the second and third groups are routinely having surveillance scans of their fistula or graft at 6 weeks following creation. Study participants undergoing standard imaging tests as part of their clinical care will also have ferumoxytol-enhanced MRA (FeMRA).
In Contrast-Enhanced Magnetic Resonance Angiography (CE-MRA) a contrast agent is injected into an arm vein using a programmable medical device called a power injector. Once the contrast has circulated to the blood vessel of interest they can be imaged with MRI and distinctly separated from surrounding non-vascular tissue. This project is designed to find the best way to administer the contrast agent during CE-MRA to produce the best images. The clinical availability of programmable power injectors facilitates the use of variable contrast rate and volume injection protocols that are based on patient specific parameters. CE-MRA is a valuable imaging tool for diagnosing abnormalities of the major blood vessels in the chest and abdomen. It is often used in conjunction with cardiac magnetic resonance (CMR) examinations to evaluate the blood vessels of the heart and lung. CE-MRA is attractive because 1) it does not involve radiation, and 2) the contrast agents used are not toxic to the kidneys and can be used in patients who are at greater risk for kidney dysfunction following iodinated contrast agents. We plan to administer a small (1cc) test amount of contrast, taking pictures as the contrast passes through the blood vessels, and analyze the results. Using this information, we will administer an individually patient-tailored injection given in multiple phases (i.e., a "multi-phasic" injection) to maintain constant contrast concentration (and therefore constant signal intensity) throughout the scan. We believe this will reduce image blurring, and improve the sharpness and likely the diagnostic quality of CE-MRA.
Prospective, non-interventional, multi-center study. The observation period for each subject covers the treatment period with Gadovist®. For each patient, the treating physician or nurse documents demographics, medical data, safety parameters and treatment signs and symptoms at the visit. Patients with severe renal impairment will be followed-up after 3 month by phone call from the investigator if in line with routine practice. Data audit/monitoring by source data verification will be done in a subset of sites and patients
The objective of the study was to compare the efficacy of Magnevist (SH L 451 A) at doses of 0.1 mmol/kg and 0.2 mmol/kg in contrast-enhanced 3D-Magnetic Resonance Angiography in three regions (abdominal, femoral, and leg regions) for visualization of arteries, evaluating 179 not assessable: caused by contrast media in the evaluation of structural abnormalities. Magnevist (SH L 451 A) was administered intravenously in a crossover design in patients with arterial disease in the abdominal to leg regions. The safety of the 0.2 mmol/kg dose was also assessed.
This trial is to show the diagnostic efficacy of Gadovist for contrast enhanced magnetic resonance angiography (CE-MRA) of the arteries.